Seating Depth

[Walkalong]

1.09 it is.
That accommodates manufacturing tolerances.
No need the particularly change load data.

I agree, just approach max with the normal caution you always would, understanding that you are slightly shorter than the OAL in the data.

 

[LiveLife]

With oal ar 1.10 a round wants to lightly stick in the chamber. "Fully drops in but needs a light tap to drop out".
At 1.09 oal the round fully drops in and freely drops out. No tap needed.

So you simply determined Max OAL with a particular random range brass?

The reason why moderator @Walkalong posted "plunk test" graphics is if you are loading right at the fringe and using that "near" Max OAL, there are other factors to consider.

You should at least feed the dummy round from the magazine and release the slide without riding it to "function test" to determine the Working OAL. Max OAL rounds can reliably feed to be used as Working OAL but not always and OAL may need to be reduced further to reliably feed and chamber from the magazine (And I would also measure OAL before/after the function test to determine if there is any bullet setback. If using multiple headstamp brass, I would check for bullet setback for sample of each headstamp as reduction in OAL, especially for heavy 9mm 147 gr bullet that will get seated deep into the case).

Check out the following comparison picture from the "plunk test" where hood of barrel makes contact with breech wall face when slide goes into full battery (Or not if dummy round is too long) - https://www.thehighroad.org/index.p...rel-find-a-max-o-a-l-with-your-bullet.506678/

As @rfwobbly illustrated in post #12 and @Walkalong linked in post #19, there's more to "plunk test" than simply dropping a dummy round in the chamber and letting it fall back out:

1. Resized case in the far left is too short and while dummy round may drop in/out freely, the round will likely "headspace" off extractor instead of headspacing off case mouth. If you are using mixed range brass that's been reloaded multiple times, since resizing carbide ring won't reach the case base/rim of brass, resized case length can continue to get shorter and reach a point where chambered round will be held back by the extractor and bullet nose dangle away from the chamber/start of rifling. This will leak more gas and slow down the case mouth/neck expansion to build pressure and if shot with longer resized cases, will likely produce more muzzle velocity variance and widen group size. I usually mark too short of cases to be shot but not picked up as there is nothing I can do to make it longer again.
2. Resized case second from left is slightly shorter than chamber to breech wall face distance but case mouth reaches forward part of chamber that narrows to seal case mouth to chamber when powder ignites. Most mixed range bras, even once-fired brass will be like this. If dummy round does not spin freely, you need to seat the bullet deeper until it does.
3. Resized case third from left is same length as chamber to breech wall face. If dummy round does not spin freely, it means the bullet nose/shoulder is contacting the rifling and should be seated deeper. If dummy round spins freely, it means resized case length is same as chamber to breech wall face and should produce greater accuracy from headspacing off case mouth and quicker sealing of gas.
4. Round on the right has bullet seated too shallow/long and nose/shoulder of bullet contacting rifling is pushing the case rim above the barrel hood. Bullet needs to be seated deeper until round drops into the chamber freely with a "plonk" and spin freely without contacting the rifling.

So measure some samples of each headstamp brass and use shorter resized cases to set the OAL as if you use longer resized cases, shorter resized cases will allow more bullet nose/shoulder above the case mouth. For this myth busting thread of 9mm OAL consistency 0.750" resized case length was used to set the OAL, which was middle of the road measurement of resized case lengths of sample cases - https://www.thehighroad.org/index.p...e-consistent-oal-on-progressive-press.921633/

And let's say 0.750" resized case length loaded to 1.09" OAL was sticky, you may need to use shorter 1.08" as Max OAL. Then, using 1.08" or 1.09", whichever Max OAL passed the "plunk test", feed the dummy round from the magazine to verify reliable feeding/chambering. If dummy goes into full battery with hesitation or does not go in full battery, you may need to incrementally shorten the OAL until you have reliable feeding.

And if the dummy round experience significant bullet setback, you should address neck tension issue so you eliminate/minimize bullet setback.

 

[9mmepiphany]

When starting reloading and developing loads, I highly recommend using cases of the same headstamp...it is as logical as using the same bullet, powder, and primers...as it removes another variable

 

[GeoDudeFlorida]

When starting reloading and developing loads, I highly recommend using cases of the same headstamp...it is as logical as using the same bullet, powder, and primers...as it removes another variable

This!
Loading a new case and being new to loading are the two scenarios where I can see buying new brass or a new box of ammo just for load development.

 

[9mmepiphany]

I can see buying new brass or a new box of ammo just for load development.

Newer reloaders often don't think about these subtleties.

I shoot a lot of RMR 147gr HMW factory seconds for practice and even matches, but using them to develop a load is a fool's errand. I starting doing it once and the varying OAL was driving me nuts...until I realized I'd grabbed the wrong bag of bullets

 

[GeoDudeFlorida]

Newer reloaders often don't think about these subtleties.

I shoot a lot of RMR 147gr HMW factory seconds for practice and even matches, but using them to develop a load is a fool's errand. I starting doing it once and the varying OAL was driving me nuts...until I realized I'd grabbed the wrong bag of bullets

Yup. That’s a forehead slap moment for sure. I’ve done very similar things more times than I’d like to remember - or will ever admit to.

 

[rfwobbly]

What's the verdict at 1.095? if that chambers freely, start there.

In my humble opinion.....
You've completely forgotten about the manufacturing tolerances present in making hundreds/thousands of cartridges for pistol shooting. What you suggest might work for bench rest rifle where you shoot 25 rounds in a whole day. But I don't know any pistol shooter that stops at 25 rounds. It's usually 250 to 600 rounds. And those higher shooting volumes translate to higher manufacturing tolerances on the ammo.

Anyone that says they have +/-0.000" tolerance on pistol ammo is either a liar, or they are spending WAY too much time on their bench. No sir, pistol ammo is more like +0.006/-0.003" tolerance when you crank up your progressive.

So with a tight fitting round, what you are setting yourself up for is an Out Of Battery (OOB) accident that will hurt the shooter and possible destroy the pistol.

I suggest you find the tightest average OAL the barrel will allow, and then subtract AT LEAST 0.015" more.

Do the risk analysis. There is absolutely NOTHING to gain from tight fitting pistol ammo, but you have everything to loose.

THINK !

 

[fxvr5]

So with a tight fitting round, what you are setting yourself up for is an Out Of Battery (OOB) accident that will hurt the shooter and possible destroy the pistol.

I suggest you find the tightest average OAL the barrel will allow, and then subtract AT LEAST 0.015" more.

Do the risk analysis. There is absolutely NOTHING to gain from tight fitting pistol ammo, but you have everything to loose.

THINK !

Is this destroyed gun a result of an out of battery firing?

 

[Bazoo]

In my humble opinion.....
You've completely forgotten about the manufacturing tolerances present in making hundreds/thousands of cartridges for pistol shooting. What you suggest might work for bench rest rifle where you shoot 25 rounds in a whole day. But I don't know any pistol shooter that stops at 25 rounds. It's usually 250 to 600 rounds. And those higher shooting volumes translate to higher manufacturing tolerances on the ammo.

Anyone that says they have +/-0.000" tolerance on pistol ammo is either a liar, or they are spending WAY too much time on their bench. No sir, pistol ammo is more like +0.006/-0.003" tolerance when you crank up your progressive.

So with a tight fitting round, what you are setting yourself up for is an Out Of Battery (OOB) accident that will hurt the shooter and possible destroy the pistol.

I suggest you find the tightest average OAL the barrel will allow, and then subtract AT LEAST 0.015" more.

Do the risk analysis. There is absolutely NOTHING to gain from tight fitting pistol ammo, but you have everything to loose.

THINK !

That makes a lot of sense. I do not load on a progressive press, so... my answers are always from a single stage and slower pace perspective.

 

[GeoDudeFlorida]

That makes a lot of sense. I do not load on a progressive press, so... my answers are always from a single stage and slower pace perspective.

Same here. I usually either skip or just skim the threads that are progressive-specific. Sometimes those threads turn into general process discussions and I stop checking in. It’s a different way of thinking from what I’ve observed. Never tried one myself so don’t know for sure.

 

[LiveLife]

You've completely forgotten about the manufacturing tolerances

... There is absolutely NOTHING to gain from tight fitting pistol ammo

I do not load on a progressive press, so... my answers are always from a single stage and slower pace perspective.

Even using same headstamp brass, depending on case wall thickness/brass alloy composition, progressive press shellplate tilt/deflection can add .003"-.005"+ variance to finished OAL.

Add to that bullet nose/ogive variance depending on brand/model of bullets used (As most RN/JHP/FP profile bullets are pushed not at tip rather further down the ogive), you have added tolerance stacking of few more thousandths.

And if you are using mixed range brass of different headstamp/case wall thickness, as well myth busted in my various threads, you can add upwards of .006"+ to the tolerance stacking.

Let's not forget another reloading variable of bullet tilting during seating which will further add to tolerance stacking of OAL variance and why many use stepped "M" style expander or stepped powder through expander (PTX) like NOE and Lee Precision's latest "Square Starting" PTX which are fast becoming standard in their die sets (Official announcement will be forthcoming after sufficient quantities are produced).

So even though you load on a single stage press, you can get some OAL variance from consistency of bullet nose, use of mixed range brass and bullet tilting during seating.

Therefore, once you determine the "absolute" Max OAL using a particular resized case length sample for a specific bullet sample, reduce the OAL by few thousandths to compensate for resized case length variance and other "reloading/manufacturing tolerance" variance that @rfwobbly outlined in detail.

And as @Walkalong and I illustrated, go through the "plunk test" process by using the barrel (For Max OAL) then function test using the magazine to determine the Working OAL.

Here's a working example of this:

When a new THR member inquired about OAL for 40S&W for IDPA/USPSA (I shot USPSA in .45ACP/9mm then 40S&W to meet both major/minor PF with single caliber using heavier 180/165 and lighter 155 gr bullets), I suggested loading longer than SAAMI max of 1.135" to see if accuracy improves unless 1.140" used was already the max working OAL - https://www.thehighroad.org/index.p...-the-rock-ultra-1911-40.920424/#post-12658103

(Pertinent to OP of this thread, from my 40S&W load development, while 1.149"/1.155" were Max OAL determined using the barrels of Glock/M&P/Lone Wolf, I ended up using 1.142" for Working OAL to reliably feed from the magazine)

When I did load development for 180 gr TCFP and RNFP, various lead/plated/jacketed produced smaller groups with longer OAL (1.149" max OAL and 1.142" working OAL for 180 gr TCFP and 1.155" working OAL for RNFP in Glock/M&P/Lone Wolf 40S&W barrels) - https://www.thehighroad.org/index.p...-for-lead-plated-bullets.743416/#post-9362819​

​

And match shooters at Brian Enos forum are now frequently loading 40S&W longer around 1.180" depending on the barrel to improve accuracy. Interestingly latest load data from Alliant for Sport Pistol and 180 gr ACME FP bullet now lists longer 1.160 OAL (Note 1.160" OAL is longer than SAAMI max of 1.135") - http://www.alliantpowder.com/reload...&weight=180&shellid=29&bulletid=439&bdid=1582​

• 40S&W 180 gr Acme FP-NLG coated Sport Pistol OAL 1.160" Max 5.0 gr (1010 fps)

 

[JohnMc]

So you simply determined Max OAL with a particular random range brass?

The reason why moderator @Walkalong posted "plunk test" graphics is if you are loading right at the fringe and using that "near" Max OAL, there are other factors to consider.

You should at least feed the dummy round from the magazine and release the slide without riding it to "function test" to determine the Working OAL. Max OAL rounds can reliably feed to be used as Working OAL but not always and OAL may need to be reduced further to reliably feed and chamber from the magazine (And I would also measure OAL before/after the function test to determine if there is any bullet setback. If using multiple headstamp brass, I would check for bullet setback for sample of each headstamp as reduction in OAL, especially for heavy 9mm 147 gr bullet that will get seated deep into the case).

Check out the following comparison picture from the "plunk test" where hood of barrel makes contact with breech wall face when slide goes into full battery (Or not if dummy round is too long) - https://www.thehighroad.org/index.p...rel-find-a-max-o-a-l-with-your-bullet.506678/

As @rfwobbly illustrated in post #12 and @Walkalong linked in post #19, there's more to "plunk test" than simply dropping a dummy round in the chamber and letting it fall back out:

1. Resized case in the far left is too short and while dummy round may drop in/out freely, the round will likely "headspace" off extractor instead of headspacing off case mouth. If you are using mixed range brass that's been reloaded multiple times, since resizing carbide ring won't reach the case base/rim of brass, resized case length can continue to get shorter and reach a point where chambered round will be held back by the extractor and bullet nose dangle away from the chamber/start of rifling. This will leak more gas and slow down the case mouth/neck expansion to build pressure and if shot with longer resized cases, will likely produce more muzzle velocity variance and widen group size. I usually mark too short of cases to be shot but not picked up as there is nothing I can do to make it longer again.
2. Resized case second from left is slightly shorter than chamber to breech wall face distance but case mouth reaches forward part of chamber that narrows to seal case mouth to chamber when powder ignites. Most mixed range bras, even once-fired brass will be like this. If dummy round does not spin freely, you need to seat the bullet deeper until it does.
3. Resized case third from left is same length as chamber to breech wall face. If dummy round does not spin freely, it means the bullet nose/shoulder is contacting the rifling and should be seated deeper. If dummy round spins freely, it means resized case length is same as chamber to breech wall face and should produce greater accuracy from headspacing off case mouth and quicker sealing of gas.
4. Round on the right has bullet seated too shallow/long and nose/shoulder of bullet contacting rifling is pushing the case rim above the barrel hood. Bullet needs to be seated deeper until round drops into the chamber freely with a "plonk" and spin freely without contacting the rifling.

So measure some samples of each headstamp brass and use shorter resized cases to set the OAL as if you use longer resized cases, shorter resized cases will allow more bullet nose/shoulder above the case mouth. For this myth busting thread of 9mm OAL consistency 0.750" resized case length was used to set the OAL, which was middle of the road measurement of resized case lengths of sample cases - https://www.thehighroad.org/index.p...e-consistent-oal-on-progressive-press.921633/

And let's say 0.750" resized case length loaded to 1.09" OAL was sticky, you may need to use shorter 1.08" as Max OAL. Then, using 1.08" or 1.09", whichever Max OAL passed the "plunk test", feed the dummy round from the magazine to verify reliable feeding/chambering. If dummy goes into full battery with hesitation or does not go in full battery, you may need to incrementally shorten the OAL until you have reliable feeding.

And if the dummy round experience significant bullet setback, you should address neck tension issue so you eliminate/minimize bullet setback.

The leftmost one is what folks who shoot .40 S&W out of a 10mm Auto barrel get. That's not for me.

Also, if your too short cases are 9mm Luger and otherwise in good condition, donate them to someone who loads 9mm Makarov from trimmed 9mm Luger.

 

[LiveLife]

if your too short cases are 9mm Luger and otherwise in good condition, donate them to someone who loads 9mm Makarov from trimmed 9mm Luger.

Very good suggestion! < Starting a "short" 9x19 to be 9x18 pile >

 

[rfwobbly]

That makes a lot of sense. I do not load on a progressive press, so... my answers are always from a single stage and slower pace perspective.

Do this and you will have a "eureka moment"....
Load 50 rounds of any auto pistol caliber you wish. Use your standard process and setup. No fair measuring OALs until you finish.
Then sit down with your caliper and measure each cartridge. Write down each OAL you measure.
You'll be shocked. We all hold a high opinion of ourselves. We may think we make the best ammo ever.
But I bet, that even on a "good day" you'll have OAL variations of at least 0.003 to 0.004".

 

[GeoDudeFlorida]

Oops! Someone made the mistake of accidentally comparing single stage presses to progressive and didn’t sing the praises of automation!

 

[Bazoo]

Do this and you will have a "eureka moment"....
Load 50 rounds of any auto pistol caliber you wish. Use your standard process and setup. No fair measuring OALs until you finish.
Then sit down with your caliper and measure each cartridge. Write down each OAL you measure.
You'll be shocked. We all hold a high opinion of ourselves. We may think we make the best ammo ever.
But I bet, that even on a "good day" you'll have OAL variations of at least 0.003 to 0.004".

My runout is about .002-.003 if I seat and crimp in the same operation (which I do most of the time), though I rarely measure OAL or runout. I mostly load cartridges that take a roll crimp, and thus, am more concerned about the consistency of my crimp than length. I of course trim my cases and segregate by brand and sometimes lot.

So, backing off .010 of what barely plunks is a good safety margin when using a progressive I take it?

When I loaded 45 acp, my runout was not any more than .002 because I seated and crimped separately, plus used a stepped expander, and sorted my brass. I didn't trim my cases though.

 

[LiveLife]

Do this and you will have a "eureka moment".... Load 50 rounds of any auto pistol caliber you wish. Use your standard process and setup. No fair measuring OALs until you finish. Then sit down with your caliper and measure each cartridge. Write down each OAL you measure.

You'll be shocked. We all hold a high opinion of ourselves. We may think we make the best ammo ever.
But I bet, that even on a "good day" you'll have OAL variations of at least 0.003 to 0.004".

Yes, absolutely agree and reasons why for conducting myth busting for OAL variance consistency to check effects of sorting by headstamp/case wall thickness:

(NOTE: Testing for these myth busting threads were done with using resized case length of .075"​

Myth busting for sorting by headstamp - https://www.thehighroad.org/index.p...al-on-progressive-press.921633/#post-12684970

Myth busting for case wall thickness - https://www.thehighroad.org/index.php?threads/myth-busting-9mm-r-p-thin-case-wall-notion.921546/

Oops! Someone made the mistake of accidentally comparing single stage presses to progressive and didn’t sing the praises of automation!

Well, I will let hard objective factual measurement data that are repeatable speak for themselves (Like letting the holes on target/group size determine which powder charge is better).

How about sample size of over 100 to show reduction of OAL variance from .005" down to .001" on progressive presses using mixed range brass unsorted by resized lengths? - https://www.thehighroad.org/index.p...al-on-progressive-press.921633/#post-12685928

 

[GeoDudeFlorida]

Yes, absolutely agree and reasons why for conducting myth busting for OAL variance consistency to check effects of sorting by headstamp/case wall thickness:

(NOTE: Testing for these myth busting threads were done with using resized case length of .075"​

Myth busting for sorting by headstamp - https://www.thehighroad.org/index.p...al-on-progressive-press.921633/#post-12684970

Myth busting for case wall thickness - https://www.thehighroad.org/index.php?threads/myth-busting-9mm-r-p-thin-case-wall-notion.921546/


Well, I will let hard objective factual measurement data that are repeatable speak for themselves (Like letting the holes on target/group size determine which powder charge is better).

How about sample size of over 100 to show reduction of OAL variance from .005" down to .001" on progressive presses using mixed range brass unsorted by resized lengths? - https://www.thehighroad.org/index.p...al-on-progressive-press.921633/#post-12685928

Seems quite a lot off topic to me but, whatever. Seating depth is not col and col is always going to be an average as a result of variance. I’m hoping the op got that quite a few posts ago so I guess that makes it an open target for the old, “MY way is better!” chest thumping to begin.

Go ahead. Preach it. I’ll make the popcorn.

 

[tws3b2]

So you simply determined Max OAL with a particular random range brass?

The reason why moderator @Walkalong posted "plunk test" graphics is if you are loading right at the fringe and using that "near" Max OAL, there are other factors to consider.

You should at least feed the dummy round from the magazine and release the slide without riding it to "function test" to determine the Working OAL. Max OAL rounds can reliably feed to be used as Working OAL but not always and OAL may need to be reduced further to reliably feed and chamber from the magazine (And I would also measure OAL before/after the function test to determine if there is any bullet setback. If using multiple headstamp brass, I would check for bullet setback for sample of each headstamp as reduction in OAL, especially for heavy 9mm 147 gr bullet that will get seated deep into the case).

Check out the following comparison picture from the "plunk test" where hood of barrel makes contact with breech wall face when slide goes into full battery (Or not if dummy round is too long) - https://www.thehighroad.org/index.p...rel-find-a-max-o-a-l-with-your-bullet.506678/

As @rfwobbly illustrated in post #12 and @Walkalong linked in post #19, there's more to "plunk test" than simply dropping a dummy round in the chamber and letting it fall back out:

1. Resized case in the far left is too short and while dummy round may drop in/out freely, the round will likely "headspace" off extractor instead of headspacing off case mouth. If you are using mixed range brass that's been reloaded multiple times, since resizing carbide ring won't reach the case base/rim of brass, resized case length can continue to get shorter and reach a point where chambered round will be held back by the extractor and bullet nose dangle away from the chamber/start of rifling. This will leak more gas and slow down the case mouth/neck expansion to build pressure and if shot with longer resized cases, will likely produce more muzzle velocity variance and widen group size. I usually mark too short of cases to be shot but not picked up as there is nothing I can do to make it longer again.
2. Resized case second from left is slightly shorter than chamber to breech wall face distance but case mouth reaches forward part of chamber that narrows to seal case mouth to chamber when powder ignites. Most mixed range bras, even once-fired brass will be like this. If dummy round does not spin freely, you need to seat the bullet deeper until it does.
3. Resized case third from left is same length as chamber to breech wall face. If dummy round does not spin freely, it means the bullet nose/shoulder is contacting the rifling and should be seated deeper. If dummy round spins freely, it means resized case length is same as chamber to breech wall face and should produce greater accuracy from headspacing off case mouth and quicker sealing of gas.
4. Round on the right has bullet seated too shallow/long and nose/shoulder of bullet contacting rifling is pushing the case rim above the barrel hood. Bullet needs to be seated deeper until round drops into the chamber freely with a "plonk" and spin freely without contacting the rifling.

So measure some samples of each headstamp brass and use shorter resized cases to set the OAL as if you use longer resized cases, shorter resized cases will allow more bullet nose/shoulder above the case mouth. For this myth busting thread of 9mm OAL consistency 0.750" resized case length was used to set the OAL, which was middle of the road measurement of resized case lengths of sample cases - https://www.thehighroad.org/index.p...e-consistent-oal-on-progressive-press.921633/

And let's say 0.750" resized case length loaded to 1.09" OAL was sticky, you may need to use shorter 1.08" as Max OAL. Then, using 1.08" or 1.09", whichever Max OAL passed the "plunk test", feed the dummy round from the magazine to verify reliable feeding/chambering. If dummy goes into full battery with hesitation or does not go in full battery, you may need to incrementally shorten the OAL until you have reliable feeding.

And if the dummy round experience significant bullet setback, you should address neck tension issue so you eliminate/minimize bullet setback.

Using my 4.5" barrel, 1.10" oal the xtp round will not set into chamber properly and will not spin. At 1.095" oal the round will set in the chamber properly and spin.
Using my 3" barrel, 1.10" oal the xtp round will not set into chamber properly and will not spin. At 1.076" it will.
So, next question is - Hodgdon data for 147gr. xtp is 3.0min. - 3.4max. w231 powder at 1.10 oal.
Would it be safe to set oal to 1.076 with 3.0 powder for Both barrels?

 

[LiveLife]

4.5" barrel, 1.10" oal the xtp round will not set into chamber properly and will not spin. At 1.095" oal the round will set in the chamber properly and spin.

3" barrel, 1.10" oal the xtp round will not set into chamber properly and will not spin. At 1.076" it will.

So looks like 1.095" is your Max OAL for 4.5" barrel and 1.076" is Working OAL for both barrels.

Have you function checked the Working OAL and fed the 1.076" round from the magazine?

next question is - Hodgdon data for 147gr. xtp is 3.0min. - 3.4max. w231 powder at 1.10 oal.
Would it be safe to set oal to 1.076 with 3.0 powder for Both barrels?

Max/Working OAL is set by the leade length of the barrel (Distance to start of rifling from chamber) and the pistol/magazine, not by published load data (Heck, most published load data don't even use real pistols rather single action universal test barrel fixtures and don't need to feed from a magazine. But for those of us who use real magazine fed pistols, we have to determine the Working OAL that will work with our magazines).

So once the Working OAL is determined, we have to use that length for the initial powder work up (To identify powder charge that will reliably extract/eject spent cases and start producing accuracy trend) and subsequent powder work up (To verify accuracy of powder charge from initial powder work up and fine tune powder charges to reduce group size). We could go shorter (I do this once most accurate powder charge is identified from subsequent powder work up and if I am not at max charge by incrementally reducing OAL by .005").

When conducting load development and if my Working OAL is shorter than published OAL, I will consider reducing my start/max charges by .2-.3 gr. Here's Hodgdon load data - https://www.hodgdonreloading.com/reloading-data-center

• 9mm 147 gr Hornady XTP W231 COL 1.100" Start 3.0 gr (755 fps) 30,100 PSI - Max 3.4 gr (845 fps) 34,300 PSI

Since your Working OAL of 1.076" is shorter than published 1.100", you could consider reducing initial powder work up start charge down to 2.8 gr and max charge down to 3.2 gr to "roughly" compensate for pressure increase.

So you could load 2.8, 3.0, 3.2 gr test rounds for the initial powder work up (Instead of 3.0, 3.2, 3.4 gr) and see which powder charge will reliably extract/eject spent cases and start to produce accuracy trends. Let's say 3.0 gr did that, then you can load 2.9, 3.0, 3.1, 3.2 gr and see which powder charge produces smallest group. Of course, you could load 2.8, 2.9, 3.0, 3.1, 3.2 gr and save yourself a trip to the range.

I’m hoping the op got that quite a few posts ago so I guess that makes it an open target for the old, “MY way is better!” chest thumping to begin.

Go ahead. Preach it. I’ll make the popcorn.

No need for chest thumping.

This was the OP:

9mm, 147gr xtp ... Hodgdon gives 1.100 COL. When I set the bullet to the Col it just didn't look right to me. Looked like it should go deeper into the case.

It just seemed a little weird to me. Seemed maybe 1.07 would be more like it should be.
It just got me wondering. How important is col. Would more or less make a lot of difference?

And @Walkalong, @rfwobbly and other members explained why OAL/COL is important for high pressure small internal case volume 9mm that can increase chamber pressure by several thousand PSI with reduction of OAL by several thousandths.

I expanded on what other members' posts by clarifying and further explaining reloading variables related to OAL/bullet seating depth and how some reloading variables could overshadow other reloading variables to affect OAL.

It's jmorris/Bart B. and other THR members to blame who questioned and challenged when I posted something that needed verifying. Hence why "myth busting" threads were started to narrow reloading variables down to one (If all possible) with measurable and repeatable data so we could myth bust or confirm a reloading variable in question.

It is not "MY way is better!" rather what has progressed and evolved on THR Handloading & Reloading subcategory over the decades. Because of these "myth busting" and "real world" threads where sample size increased to hundreds and over 10,000 rounds for 22LR comparison testing that I can say:

• Some digital scales can detect below 0.1 gr resolution of most beam scales to resolve Varget down to single kernel (.02-.03 gr) and Promo down to single granule (1-2 granules weigh .01 gr)
• 9mm 115 gr FMJ loaded to shorter 1.130" OAL is more accurate than loaded longer 1.150" (And loaded to even shorter 1.110" is more accurate than 1.130")
• Digital scales using strain gauge that drift zero could have work done to mounting plate to eliminate zero drift
• "Cheap" FA dial calipers verified with pin gages and feeler gages can read accurate to .001" confirmed by Brown & Sharpe micrometer
• Ruger 10/22 factory 18.5" barrel with some accurizing work can produce 1/2"-3/4" 50 yard groups with CCI SV and 3/4"-1" groups with Aguila 40 gr LRN/CPRN
• Some progressive presses using RMR 115 gr FMJ can reduce OAL variance down from .005" to .001" depending on headstamp/thickness of case wall
• One Shot case lube will not induce bullet setback wet or dry
• Etc., Etc.

 

[rfwobbly]

My runout is about .002-.003 if I seat and crimp in the same operation (which I do most of the time), though I rarely measure OAL or runout. I mostly load cartridges that take a roll crimp, and thus, am more concerned about the consistency of my crimp than length. I of course trim my cases and segregate by brand and sometimes lot.

So, backing off .010 of what barely plunks is a good safety margin when using a progressive I take it?

When I loaded 45 acp, my runout was not any more than .002 because I seated and crimped separately, plus used a stepped expander, and sorted my brass. I didn't trim my cases though.

Exactly why do you want the auto pistol bullet placed so close to the rifling ? There is absolutely nothing to gain, but everything to loose. Everything, as in fingers and eye balls. Why are you so fixated on using small clearances ??

There are MANY sources of variation !!

Here's another source: Case Length. I have 9x19 cases that are 0.750" long, and I have cases that are 0.743" long. For any OAL I might use, if the case is shorter, then the bullet is protruding from the case mouth further. So for my shortest case, the bullet is protruding 0.007" longer. If we couple that 0.007" with your reported 0.003" length variation... then the 0.007" plus 0.003" just ate up your entire 0.010" clearance.

It's got nothing to do with what type of press you use. It's got everything to do with safety for the humans involved.

 

[tws3b2]

So looks like 1.095" is your Max OAL for 4.5" barrel and 1.076" is Working OAL for both barrels.

Have you function checked the Working OAL and fed the 1.076" round from the magazine?


Max/Working OAL is set by the leade length of the barrel (Distance to start of rifling from chamber) and the pistol/magazine, not by published load data (Heck, most published load data don't even use real pistols rather single action universal test barrel fixtures and don't need to feed from a magazine. But for those of us who use real magazine fed pistols, we have to determine the Working OAL that will work with our magazines).

So once the Working OAL is determined, we have to use that length for the initial (To identify powder charge that will reliably extract/eject spent cases and start producing accuracy trend) and subsequent powder work up (To verify accuracy of powder charge from initial powder work up and fine tune powder charges to reduce group size). We could go shorter (I do this once most accurate powder charge is identified from subsequent powder work up and if I am not at max charge by incrementally reducing OAL by .005").

When conducting load development and if my Working OAL is shorter than published OAL, I will consider reducing my start/max charges by .2-.3 gr. Here's Hodgdon load data - https://www.hodgdonreloading.com/reloading-data-center

• 9mm 147 gr Hornady XTP W231 COL 1.100" Start 3.0 gr (755 fps) 34,100 PSI - Max 3.4 gr (845 fps) 34,300 PSI

Since your Working OAL of 1.076" is shorter than published 1.100", you could consider reducing initial powder work up start charge down to 2.8 gr and max charge down to 3.2 gr to "roughly" compensate for pressure increase.

So you could load 2.8, 3.0, 3.2 gr test rounds for the initial powder work up (Instead of 3.0, 3.2, 3.4 gr) and see which powder charge will reliably extract/eject spent cases and start to produce accuracy trends. Let's say 3.0 gr did that, then you can load 2.9, 3.0, 3.1, 3.2 gr and see which powder charge produces smallest group. Of course, you could load 2.8, 2.9, 3.0, 3.1, 3.2 gr and save yourself a trip to the range.


No need for chest thumping.

This was the OP:

And @Walkalong, @rfwobbly and other members explained why OAL/COL is important for high pressure small internal case volume 9mm that can increase chamber pressure by several thousand PSI with reduction of OAL by several thousandths.

I expanded on what other members' posts by clarifying and further explaining reloading variables related to OAL/bullet seating depth and how some reloading variables could overshadow other reloading variables to affect OAL.

It's jmorris/Bart B. and other THR members to blame who questioned and challenged when I posted something that needed verifying. Hence why "myth busting" threads were started to narrow reloading variables down to one (If all possible) with measurable and repeatable data so we could myth bust or confirm a reloading variable in question.

It is not "MY way is better!" rather what has progressed and evolved on THR Handloading & Reloading subcategory over the decades. Because of these "myth busting" and "real world" threads where sample size increased to hundreds and over 10,000 rounds for 22LR comparison testing that I can say:

• Some digital scales can detect below 0.1 gr resolution of most beam scales to resolve Varget down to single kernel (.02-.03 gr) and Promo down to single granule (1-2 granules weigh .01 gr)
• 9mm 115 gr FMJ loaded to shorter 1.130" OAL is more accurate than loaded longer 1.150" (And loaded to even shorter 1.110" is more accurate than 1.130")
• Digital scales using strain gauge that drift zero could have work done to mounting plate to eliminate zero drift
• "Cheap" FA dial calipers verified with pin gages and feeler gages can read accurate to .001" confirmed by Brown & Sharpe micrometer
• Ruger 10/22 factory 18.5" barrel with some accurizing work can produce 1/2"-3/4" 50 yard groups with CCI SV and 3/4"-1" groups with Aguila 40 gr LRN/CPRN
• Some progressive presses using RMR 115 gr FMJ can reduce OAL variance down from .005" to .001" depending on headstamp/thickness of case wall
• One Shot case lube will not induce bullet setback wet or dry
• Etc., Etc.

I've not function tested yet. I'll make a couple dummy rounds tomorrow and give them a try.

 

[fxvr5]

Exactly why do you want the auto pistol bullet placed so close to the rifling ? There is absolutely nothing to gain, but everything to loose. Everything, as in fingers and eye balls. Why are you so fixated on using small clearances ??

How much will pressure increase in a 9mm if the bullet is touching the lands as opposed to being .010" away? You must be aware of some pressure numbers if you're saying the gun will explode. Please share them with us.

 

[Bazoo]

Exactly why do you want the auto pistol bullet placed so close to the rifling ? There is absolutely nothing to gain, but everything to loose. Everything, as in fingers and eye balls. Why are you so fixated on using small clearances ??

There are MANY sources of variation !!

Here's another source: Case Length. I have 9x19 cases that are 0.750" long, and I have cases that are 0.743" long. For any OAL I might use, if the case is shorter, then the bullet is protruding from the case mouth further. So for my shortest case, the bullet is protruding 0.007" longer. If we couple that 0.007" with your reported 0.003" length variation... then the 0.007" plus 0.003" just ate up your entire 0.010" clearance.

It's got nothing to do with what type of press you use. It's got everything to do with safety for the humans involved.

You misunderstand.

I'm not talking about seating my bullet close to the rifling, I'm talking about consistency in cartridge overall length measurements.

I'm in total agreement about giving plenty of clearance between your bullet and rifling for auto pistol cartridges.

When I said "So, backing off .010 of what barely plunks is a good safety margin when using a progressive I take it?" It should have read... "So, backing off .010 of what barely plunks is a good safety margin when your max length is too long to chamber without hitting the lands?"

 

[243winxb]

Tested today-
9mm Luger in Taurus G3C.
Bullet- 163 gr lswc, Saeco #382, .3568" sized diameter. Length .707"
Loaded COL 1.026" Head to Shoulder .778"

Load data found for HS-6. Start 3.0 grs to 3.7 grs for 160 gr coated bullet. Fed 200 Mag Primer used. Worked up to 3.7 grs, shot 5 rounds, standing, 2 hands, 7 yards.

Ok with Blazer range brass. Jammed with 1 USA brass that measured .001" to large in the case body. Right at the bullets base.
A known problem with some brass, bullet combinations.

Not a loading i normally would use, just a test.