9mm 124Gr. RMR Nuke and Canik Rival Min. OAL Concerns

[CurryCornDog]

@CurryCornDog, welcome to THR. Lots of great advice here on the forums!


It can, depending on a number of factors including how much further seating depth, the powder, and the bullet technology. I treat the faster powders as being more sensitive than the slower powders, and jacketed bullets more than lead/coated bullets. If you were saying you’re using Titegroup, then, that’s the powder that I shy away from if forced to load at less than published COLs.
As mentioned before, it’s the seating depth that’s the consideration here. If you could find someone who had 124 XTP JHPs, you could see how that bullet OAL compares to the one you’re loading, and then see if you really are seating them deeper. My 124 XTPs measure .574” +/- .001”.
If I’m forced to load at a COL less than the published data, I’ll subtract a tenth of a grain from the min for every ten thousandths less than the COL. That’s just my rule of thumb for my reloading.


I used to try to use a slower powder for my minor IDPA load, but it was very smoky and very dirty. It happened to be WSF. I switched to Sport Pistol and N320, but something like 231 or 244 works well at minor PF. Hotter loads are safer with a slower powder. I’d recommend you get two different powders. You may also want to investigate chamber reamers, preferably with a gunsmith - it would solve the COL issue.

Thanks for the welcome! Yes, my research on many sources have concluded XTPs to be an overall length of about .574-.579". I know my specific batch of Nukes to be .543-.5455" (sample size of 20/1000 measured over two different packaged bags, and sample size will grow as I spot check all dimensions along the way).

I agree with you on the hotter vs. softer powders which is why I went with AA#5 to begin with. It likes to burn clean when hot of course. Smaller powder chamber* usually = a more excited round, so less could be more in this instance.

I had an inkling, even though I'm a newbie, that judging by the pictures seen of the Nukes, the ogive would be quite weird to work with. Never thought they would be this weird though lol. I figured a more forgiving powder would work well with this, and although the margins are wider than most, shortening the COL will, in theory, still have less sensitivity restrictions than a more excititing compound.

As for the powder amount Vs. COL adjustment, seems as though you have a few in agreement with you in this thread, and you can count me as one of them. It's a fair way to ensure that at least during work-up, I'm going to start off safe with no...unexpected outcomes.

 

[CurryCornDog]

For defensive rounds loaded near max/max load data and match rounds that must be more accurate, I would use headstamp and casewall thickness that didn't produce any bullet setback - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

(As to loading own defensive rounds, we had this discussion many times before on THR and while there nothing wrong with loading own defensive rounds, I prefer to use factory ammunition for SD/HD as I rather hand police/LE couple boxes of factory ammunition for evidence instead of them taking my entire reloading equipment/components for duration of trial in case they needed to duplicate the defensive load )

As to powder selection, in general slower burning powders produce optimal accuracy at near max/max load data and for 130 "minor" power factor loads, faster burning powders around Titegroup/N320/Sport Pistol burn rate may produce more efficient powder burn and chamber pressure build for accuracy than No. 5 (Compare groupings of powders by burn rate half way down the linked post) - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12415502

FYI, these are most popular powders used for USPSA minor PF (130) loads - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12415502

• Production (9mm) - Titegroup 35%, N320 23%, Sport Pistol 16%

For decades, I not only used WSF for USPSA major power factor loads but also for "duplicate" defensive loads using same Speer Gold Dot HP/Remington Golden Saber JHP bullets/projectiles for training drill "practice" due to higher muzzle velocities and accuracy WSF produced but when Alliant released BE-86, switched from WSF as BE-86 produced higher velocities and greater accuracy/smaller groups (Rumbling is BE-86 is OEM powder used for decades to load various factory premium rounds like Speer Gold Dot/Federal HST and other manufacturers finally released for reloading as "canister" powder) - https://reloadingdata.speer.com/downloads/speer/reloading-pdfs/handgun/9mm_Luger__124_rev1.pdf

• 9mm 124 gr Speer GDHP BE-86 COL 1.120" Start 5.4 gr (1124 fps) - Max 6.0 gr (1199 fps)
• 9mm 124 gr Speer GDHP No. 5 COL 1.120" Start 5.7 gr (963 fps) - Max 6.4 gr (1069 fps)

And Hodgdon load data (BTW, HAP is same bullet as XTP but without expansion cuts for more reliable feeding for match shooting) - https://www.hodgdonreloading.com/reloading-data-center

• 9mm 125 gr Hornady HAP WSF COL 1.069" Start 4.3 gr (991 fps) - Max 5.0 gr (1,083 fps)
• 9mm 124 gr Hornady XTP No. 5 COL 1.060" Start 4.8 gr (905 fps) - Max 5.7 gr (1,075 fps)

Additional issues for bullet setback are affect on chamber pressure and accuracy. As illustrated by OAL/COL change (bullet setback) vs pressure chart below, even small change of .005" can increase pressure by around 4,000 PSI for 9mm and 8,000 PSI for 40S&W using Ramshot Zip that has comparable burn rate of W231/HP-38.

So if you are at max charge and experience significant bullet setback, you could be over published max pressure. And if your "chambered OAL variance"/bullet setback is inconsistent, then your accuracy will likely be affected. Especially for defensive rounds that are loaded at higher muzzle velocities using near max/max charges and match rounds that must produce smallest groups, I prefer to use bullet/case wall thickness combination that does not produce any bullet setback (And preferably once-fired brass that are more malleable than work hardened brass that's been reloaded multiple times).

And keep in mind that cases can get shorter as it is repeatedly reloaded and shorter resized cases that are work hardened (think brass spring back) will apply less neck tension on bullet base than longer resized cases with less number of reloading (think malleability of brass). So for maximum neck tension and greater accuracy, use longest resized cases sorted by headstamp (that won't produce bullet setback) that are once-fired or have least amount of reloadings.

BTW, results from bullet setback testing from myth busting thread using different diameter bullets - https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12503881

Wow! I appreciate such a thorough response. To start, I agree with you on defensive loads remaining as factory as that's one less thing the prosecutor will have to use against the defender. I have a few hundred rounds of 124 gr. HST for just such a reason. I have been around firearms my whole life and have helped instruct many a classroom on concealed carry. That is a hard cut rule for me.

What I meant was having a stockpiled round that's more effective than ball on hand, should the need arise and all law goes out the window. I like to be very minimalistic with materials to help decrease confusion unless needed, but yes, other bullets are still worth looking into as while I know firearms, not yet equal in competence in reloading.


As to the rest of your response; you really do have a ton of knowledge up in the ol' library, don't ya? Thank you for being so thorough and thoughful on your responses. That will give me a lot to read over as I enjoy my "morning" coffee (it's Sunday. Whaddaya want from me!? Lol).

 

[mdi]

"I just haven't found a clear answer or consensus, is all.".
Unfortunately, this is true for reloading forums that have more than one member. Forums are free and no minimum experience or credentials are necessary. One has to read, double check each "reasonable" response, and determine what info to keep and what to dispose of. When I have a question, I often ask on a forum, find an answer I feel good about, check answers against trusted texts, and test myself. But talking about reloading (swapping stories) is fun and quite a bit can be learned...

 

[CurryCornDog]

"I just haven't found a clear answer or consensus, is all.".
Unfortunately, this is true for reloading forums that have more than one member. Forums are free and no minimum experience or credentials are necessary. One has to read, double check each "reasonable" response, and determine what info to keep and what to dispose of. When I have a question, I often ask on a forum, find an answer I feel good about, check answers against trusted texts, and test myself. But talking about reloading (swapping stories) is fun and quite a bit can be learned...

Of course! That's...precisely why I'm here lol. I am of course also hoping to learn as much as I can and gain as much experience as possible. Given enough time I plan to return the favor to new shooters as well once I am confident in my knowledge and responses. It's only fair!

 

[sevt_chevelle]

You could send your barrel out to be throated and not have to worry about it anymore.

CZ is another brand that is famous for short throats. Anyways, I called and talked to Dave at Monson reamers, got a finishing reamer.
Reamed a few very short throated barrels, increased the throat by about .020 to .025.

Your nitride barrel will eat HSS reamer, but companies like patriot defense can handle it.

 

[CurryCornDog]

You could send your barrel out to be throated and not have to worry about it anymore.

CZ is another brand that is famous for short throats. Anyways, I called and talked to Dave at Monson reamers, got a finishing reamer.
Reamed a few very short throated barrels, increased the throat by about .020 to .025.

Your nitride barrel will eat HSS reamer, but companies like patriot defense can handle it.

Good to know. I'd rather keep it stock for now, as this is also a firearm I plan to carry in winter months. As a hard rule for myself, any firearm I carry as well as ammo for self-defense will remain stock and factory in every respect. Now, having another barrel for competition, on the other hand...that gives me something to ponder should I go for another angrier powder.

 

[LiveLife]

Wow! I appreciate such a thorough response.

That will give me a lot to read over as I enjoy my "morning" coffee

Glad to help out a fellow THR member. And welcome to THR.

Many of us have been there and done that. And open public forums like THR exist so people don't have to "reinvent the wheel" again and again for something that's been tried and proven multiple times, even to the point of "myth busted".

And here's some more reading for your morning coffee. Enjoy.

This is what I was going to post, do the math using the OALs and bullet lengths to figure how deep they seat in the case to compare vs simply OAL.

But that meant you would have to do the arithmetic to figure out the OAL to adjust your seating die, we can't have that any more.

We all have reloading instruments capable of measuring to .001" (verified by pin gages) and certainly can do some simple math for our load developments in regards to case fill vs bullet seating depth for specific Working OAL.

As for the powder amount Vs. COL adjustment

Here's an example of "reloading math" we did for 9mm RMR 124 gr FMJ RN and WST (There is no current published load data from Hodgdon for WST in 9mm) - https://www.thehighroad.org/index.p...er-target-published-load-data-for-9mm.870180/

I measured several 9mm RMR 124 gr FMJ RN and longer bullets measure .598"

So using OAL/COL of 1.135", my max case fill is:

OAL - Bullet length = 1.135" - .598" = .537"
​

I measured some resized WIN cases and got .747" as average resized case length.​

So I subtract max case fill from average resized case length and I get .747" - .537" = .210"

I then used the end of my dial calipers to mark the inside of the case and filled it with WST to mark and weighed the charge which came out to 4.6 gr.​

So for .598" length 124 gr RN bullet loaded to 1.135" OAL, max charge of WST at bullet seating depth is 4.6 gr.
​

Once you determine the Working OAL that will work with your pistol/barrel/magazine, you can use the same math outlined above to determine max case fill/bullet seating depth for that OAL. And if published max charge is less than max case fill powder charge, you are good to go (But if your Working OAL/bullet seating depth is shorter than published, consider reducing start/max charges by .2-.3 gr).

 

[CurryCornDog]

Glad to help out a fellow THR member. And welcome to THR.

Many of us have been there and done that. And open public forums like THR exist so people don't have to "reinvent the wheel" again and again for something that's been tried and proven multiple times.

And here's some more reading for your morning coffee. Enjoy.


We all have reloading instruments capable of measuring to .001" (verified by pin gages) and certainly can do some simple math for our load developments in regards to case fill vs bullet seating depth for specific Working OAL.


Here's an example of "reloading math" we did for 9mm RMR 124 gr FMJ RN and WST (There is no current published load data for WST in 9mm) - https://www.thehighroad.org/index.p...er-target-published-load-data-for-9mm.870180/

I measured several 9mm RMR 124 gr FMJ RN and longer bullets measure .598"

So using OAL/COL of 1.135", my max case fill is:

OAL - Bullet length = 1.135" - .598" = .537"
I measured some resized WIN cases and got .747" as average resized case length.​

So I subtract max case fill from average resized case length and I get .747" - .537" = .210"
I used the end of my dial calipers to mark the inside of the case and filled it with WST to mark and weighed the charge - 4.6 gr.​

So for .598" length 124 gr RN bullet loaded to 1.135" OAL, max charge of WST before powder compression is 4.6 gr.
​

Once you determine the Working OAL that will work with your pistol/barrel/magazine, you can use the same math outlined above to determine max case fill/bullet seating depth for that OAL. And if published max charge is less than max case fill powder charge, you are good to go (But if your Working OAL/bullet seating depth is shorter than published, consider reducing start/max charges by .2-.3 gr).

Looks like I was on the right track with my logic! I did a similiar equation using an XTP 124 gr. as baseline at minimum safe seating depth according to my manuals. At 1.060, the XTP is seated .261" into the case*. Comparing that to my RMR Nukes sitting at Working OAL (1.057"), math says I'm seated to .2355". I have .0255* extra room to play with in order to keep the same safety margins as an XTP.

Not that I will use that extra space by stuffing the bullet in to 1.03" territory, but I am willing to bet with full confidence that apples to apples charges will yield me a lower fps and thus lower pressures with the same powder between the two projectiles.

 

[LiveLife]

Looks like I was on the right track with my logic! I did a similiar equation using an XTP 124 gr. as baseline at minimum safe seating depth according to my manuals. At 1.060, the bullet is seated .261" into the chamber. Comparing that to my RMR Nukes sitting at Working OAL (1.057"), math says I'm seated to .2355". I have .0255* extra room to play with in order to keep the same safety margins as an XTP.

Keep in mind that all the calculations and juggling of numbers won't matter if round experiences setback when bullet nose slams against the feed ramp during feeding.

Remember the OAL reduction vs pressure chart? https://www.thehighroad.org/index.p...un-brass-worth-it.912195/page-2#post-12454962

For 9mm with Ramshot Zip which has comparable burn rate of W231/HP-38, reduction of OAL by small .005" will increase chamber pressure by 4000 PSI. (And even some factory rounds will experience bullet setback around .005" and more)

So even with published max charge being less than max case fill/bullet seating depth for your Working OAL, if bullet experiences setback during feeding, you could be over max SAAMI pressures by several thousand PSI. And if your mixed range brass has weakened spot from multiple reloadings/resizings, especially 9mm Major brass, case wall failure/rupture could occur. If case wall failure produces case neck split, not much of an issue but if case wall failure occurs at case base, KaBoom/blowout towards magazine and shooting hands could happen.

So if using mixed range brass, check for bullet setback by feeding dummy rounds from the magazine and releasing the slide without riding it and use the bullet diameter/headstamp brass combination with thick enough wall to not produce any bullet setback if you want more consistent pressures and greater accuracy - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

And if I run across 9mm brass that's particularly hard to resize, I will visually inspect and chamber in tightest barrel I have. If second attempt at resizing won't fully chamber in the tightest barrel freely, I will deem the brass overly expanded (Could be 9mm Major brass that should not be reloaded again) and cull it for recycling.

Be safe.

 

[CurryCornDog]

Keep in mind that all the calculations and juggling of numbers won't matter if round experiences setback when bullet nose slams against the feed ramp during feeding.

Remember the OAL reduction vs pressure chart? https://www.thehighroad.org/index.p...un-brass-worth-it.912195/page-2#post-12454962

For 9mm with Ramshot Zip which has comparable burn rate of W231/HP-38, reduction of OAL by small .005" will increase chamber pressure by 4000 PSI. (And even some factory rounds will experience bullet setback around .005" and more)

So even with published max charge being less than max case fill/bullet seating depth for your Working OAL, if bullet experiences setback during feeding, you could be over max SAAMI pressures by several thousand PSI. And if your mixed range brass has weakened spot from multiple reloadings/resizings, especially 9mm Major brass, case wall failure/rupture could occur. If case wall failure produces case neck split, not much of an issue but if case wall failure occurs at case base, KaBoom/blowout towards magazine and shooting hands could happen.

So if using mixed range brass, check for bullet setback by feeding dummy rounds from the magazine and releasing the slide without riding it and use the bullet diameter/headstamp brass combination with thick enough wall to not produce any bullet setback if you want more consistent pressures and greater accuracy - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

And if I run across 9mm brass that's particularly hard to resize, I will visually inspect and chamber in tightest barrel I have. If second attempt at resizing won't fully chamber in the tightest barrel freely, I will deem the brass overly expanded (Could be 9mm Major brass that should not be reloaded again) and cull it for recycling.

Be safe.

Understood. I have 20 dummies mocked up and plunked. Time to reassemble this bad boy and get a-rackin'!

 

[LiveLife]

I have 20 dummies mocked up and plunked. Time to reassemble this bad boy and get a-rackin'!

Will be interesting to see how much bullet setback you will experience and particularly which headstamp.

Hopefully you will find some headstamp brass that won't produce any bullet setback.

My guess would be WIN, R-P with "." to the right, regular R-P, Starline for most common domestic brass as I have experienced bullet setback with other headstamp brass.

 

[Dudedog]

I measured several 9mm RMR 124 gr FMJ RN and longer bullets measure .598"

So using OAL/COL of 1.135", my max case fill is:

OAL - Bullet length = 1.135" - .598" = .537"
I measured some resized WIN cases and got .747" as average resized case length.
So I subtract max case fill from average resized case length and I get .747" - .537" = .210"

I then used the end of my dial calipers to mark the inside of the case and filled it with WST to mark and weighed the charge which came out to 4.6 gr.

So for .598" length 124 gr RN bullet loaded to 1.135" OAL, max charge of WST at bullet seating depth is 4.6 gr.

This seems to imply that 4.6 is the MAX safe charge.

Isn't 4.6 the most WST you can put in without compression?
Just because a load is not compressed doesn't mean it is safe IMO.
I don't have any Titegroup on hand to check but I think the above logic might lead to an overload if you used it with Titegroup which is much denser than WST.

 

[Click_Here]

I couldnt get the plunk for my CZ or Ruger PCC with my handloads. They would "barely" plunk but I wasnt about to keep seating deeper out of comfort. I simply took a few and fired them out of both my CZ and Ruger PCC. It was a risk but, the fact that they didnt plunk seemed to mean squat.

 

[CurryCornDog]

Will be interesting to see how much bullet setback you will experience and particularly which headstamp.

Hopefully you will find some headstamp brass that won't produce any bullet setback.

My guess would be WIN, R-P with "." to the right, regular R-P, Starline for most common domestic brass as I have experienced bullet setback with other headstamp brass.

Hey there!

Sorry it took so long to give an update. So I tried racking three dummies and this is what happened. In case you're curious, all three of varying lengths went in just fine and chambered completely.

Test was done placing round in magazine, inserting mag with slide closed, racking the slide by pulling the slide back and letting the slide drop free to return to battery on its own, as standard for reloading. These are the results. Brass used was Blazer once fired.

RMR MPR Nuke 124 Gr. Setback Test
Round 1:
Start OAL- 1.0590
After rack OAL- 1.0575

Round 2:
Start OAL- 1.0635
After rack OAL- 1.0620

Round 3:
Start OAL- 1.060
After rack OAL- 1.0590

**So all rounds consistently set back between .001 and .0015.**

Federal HST 124 Gr. Setback Test

Round 1:
Start OAL- 1.0995
After rack OAL- 1.0990
After rack 2 OAL- 1.0980

One difference I see between both rounds side by side is the HST is much more conical than the Nuke. Makes sense that setback would be less with the HST as there is less of the bullet's face contacting the ramp as it chambers. Also, Federal/CCI/Speer (same company, whatever they call themselves) like to put seals around their primers and around the bullet/case connection on premium rounds, so perhaps those two things combined promote a more consistent length over abuse (People unloading every day and not cycling their rounds through mag).


I never plan to carry the Nuke rounds, so if they enter the chamber they're doing it once only to come out to punch paper or hit steel. All research that I can find says this to be an acceptable level of setback, permitting I am not often racking the same Round into my chamber, which is something i try to avoid regardless of ammo used*.


Your thoughts?

 

[CurryCornDog]

I couldnt get the plunk for my CZ or Ruger PCC with my handloads. They would "barely" plunk but I wasnt about to keep seating deeper out of comfort. I simply took a few and fired them out of both my CZ and Ruger PCC. It was a risk but, the fact that they didnt plunk seemed to mean squat.

So...you didn't want to seat deeper to pass plunk, but shoving them in on the lands was the safer bet in your eyes? I would guess setback may have been the only thing saving ya my guy lol

 

[Click_Here]

So...you didn't want to seat deeper to pass plunk, but shoving them in on the lands was the safer bet in your eyes? I would guess setback may have been the only thing saving ya my guy lol

Im using the same 124gr RMR Nukes. I wouldnt call it shoving lol, there was no setback on the rounds after sending the slide home on a few of the dummy rounds. They just simply would not "plunk" like they would in my other 9's.

I was in your shoes, trying to figure out how deep I should seat to plunk in these tight chambers. Seating horrendously deep to plunk, using the sharpie test, crimping more and more...etc. Theres enough on the web about tight throats where plunking just wasnt happening.

Im not loading max, more middle with True Blue and i've already gone through 500 of these RMR's at that non plunked length...

 

[CurryCornDog]

Im using the same 124gr RMR Nukes. I wouldnt call it shoving lol, there was no setback on the rounds after sending the slide home on a few of the dummy rounds. They just simply would not "plunk" like they would in my other 9's.

I was in your shoes, trying to figure out how deep I should seat to plunk in these tight chambers. Seating horrendously deep to plunk, using the sharpie test, crimping more and more...etc. Theres enough on the web about tight throats where plunking just wasnt happening.

Im not loading max, more middle with True Blue and i've already gone through 500 of these RMR's at that non plunked length...

Ooooh I see. I appreciate the input! What's been your OAL and load so far with true blue, if you don't mind me asking? And did the round work well for you otherwise?

 

[Click_Here]

Ooooh I see. I appreciate the input! What's been your OAL and load so far with true blue, if you don't mind me asking? And did the round work well for you otherwise?

After testing, I ended up sticking with 1.062 with 5.3gr of TrueBlue so that the round would work for the two tight 9's and pretty much promises they'll work in all the others.

 

[LiveLife]

I tried racking three dummies and this is what happened. In case you're curious, all three of varying lengths went in just fine and chambered completely.

Test was done placing round in magazine, inserting mag with slide closed, racking the slide by pulling the slide back and letting the slide drop free to return to battery on its own, as standard for reloading. These are the results. Brass used was Blazer once fired.

Bullet setback of .0005" to .0015" is actually pretty good for thinner case walled Blazer brass. And you only need to chamber once as typically, rounds in the magazine will only experience one chambering.

Your thoughts?

Since Blazer brass has thinner case wall, if you have other headstamp brass with thicker case wall (Like WIN, R-P, R-P ".", Starline, etc.), I am curious what amount of bullet setback, if at all, your dummy rounds would experience.

 

[CurryCornDog]

Bullet setback of .0005" to .0015" is actually pretty good for thinner case walled Blazer brass. And you only need to chamber once as typically, rounds in the magazine will only experience one chambering.


Since Blazer brass has thinner case wall, if you have other headstamp brass with thicker case wall (Like WIN, R-P, R-P ".", Starline, etc.), I am curious what amount of bullet setback, if at all, your dummy rounds would experience.

It mostly is all Blazer at the moment. About 500 cases of it. Basically what my range sells, so I grabbed what I shot over the last month or so and got the ball rolling with that. But I'll sort through and see if there's any others and give those a try. Worth a shot, and will give me something to look for in once fired bulk bags in the future.

I've read through a ton of everything you've researched and posted for me to read, and I was kind of surprised myself compared to the findings you had posted. These Nukes are pretty chunky, but seems to me the feed ramp on the rival is pretty gentle on ammo compared to many other firearms, so looks like I got lucky picking that as my competition piece! That wasn't a thought in my mind when I got it, just fell in love with the trigger lol. Especially considering people reporting up to 5 HUNDREDTHS of set back with other firearms! That's something I'd be terrified to find out and would get me started on supergluing the bastards in! Real pucker factor right there.

Thanks again for taking a look at my findings. Going off all the great info you've provided, I'll use Blazer as a baseline for everything else I find. This seems acceptable so far, so looks like it can only go up from here! It is awesome to know you and so many others on here are so willing to double check the work of someone dipping their toe into the scene. You rock!

 

[LiveLife]

Here's an example of "reloading math" we did for 9mm RMR 124 gr FMJ RN and WST ... So for .598" length 124 gr RN bullet loaded to 1.135" OAL, max charge of WST at bullet seating depth is 4.6 gr.

This seems to imply that 4.6 is the MAX safe charge

No such claim was made by my post.

What I posted was we can use math to determine bullet seating depth and max case fill of powder based on Working OAL and bullet length as illustrated by max case fill calculations - https://www.thehighroad.org/index.p...-min-oal-concerns.916665/page-2#post-12567323

And if published max charge was less than max case fill, published max charge would be safe to use, as long as Working OAL/bullet seating depth was not shorter than published OAL, in which case I suggested reduction of start/max charges by .2-.3 gr.

Once you determine the Working OAL that will work with your pistol/barrel/magazine, you can use the same math outlined above to determine max case fill/bullet seating depth for that OAL. And if published max charge is less than max case fill powder charge, you are good to go. (But if your Working OAL/bullet seating depth is shorter than published, consider reducing start/max charges by .2-.3 gr).

And since OP wants to load higher velocity "defensive" loads in addition to minor power factor IDPA match loads, I also posted that OP should check for bullet setback as using published max could become overpressure if there is bullet setback. (And no bullet setback loads would be more accurate for match shooting)

For 9mm with Ramshot Zip which has comparable burn rate of W231/HP-38, reduction of OAL by small .005" will increase chamber pressure by 4000 PSI.

So even with published max charge being less than max case fill/bullet seating depth for your Working OAL, if bullet experiences setback during feeding, you could be over max SAAMI pressures by several thousand PSI.

For defensive rounds loaded near max/max load data and match rounds that must be more accurate, I would use headstamp and casewall thickness that didn't produce any bullet setback

Hence why I suggested OP test different headstamp cases to not produce bullet setback and linked to myth busting thread done for neck tension and bullet setback - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

Will be interesting to see how much bullet setback you will experience and particularly which headstamp.

Hopefully you will find some headstamp brass that won't produce any bullet setback. My guess would be WIN, R-P with "." to the right, regular R-P, Starline for most common domestic brass as I have experienced bullet setback with other headstamp brass.

 

[LiveLife]

The seating depth is really what makes the difference in pressure

Yes, this is true. While we use "OAL/COL" when discussing load development, what we are really saying is "bullet seating depth" which is derived by subtracting bullet length from Working OAL.

While we may fuss over "finished OAL", what really matters is the "chambered OAL" after any bullet setback which ultimately determines chamber pressure.

And if we want to pursue match loads that must be accurate instead of range blasting ammo that just needs to cycle the slide and go bang (Since different bullet seating depths will produce differing chamber pressures and varying degrees of muzzle velocities), we want to use bullet diameter/OAL/headstamp brass with particular case wall thickness that won't produce bullet setback.

 

[rfwobbly]

Published here before, but it still applies....

Auto pistol cartridges do not use a crimp cannelure to position the bullet, as revolver cartridges do. Therefore, cartridge OAL for the auto pistol is actually not a single, fixed dimension, but rather an acceptable range within which you’ll be safe. This “range” is defined by 2 sets of measurement “limits”. Some of these limits are set by the realities of reloading, other limits are imposed by SAAMI physical limits. Both these "limits" represent hard boundaries which the reloader MUST obey, and thus work within.

• The outer limits are set by SAAMI. The 9x19 Luger cartridge cannot be longer than 1.169” or it may not physically fit into the magazine. SAAMI also advises that the cartridge should not be shorter than 1.000” due to feeding considerations. You can look this up on the SAAMI web site.
  
  
• The inner limits are defined by the bullet-to-barrel fit for the longer dimension. The shorter dimension should be the shortest published OAL you can find in your load manuals. (Of course with calculation, you can always compensate and go shorter. But if you don’t have the means or the experience, then stay with the book OAL.)

Taken together these 2 sets of limits result in a graphic that looks like this…

• Hard facts forming hard rules which result in "bad things", if you ignore them. That's the "Science of Reloading".

• Within the range of safe limits, the final chosen OAL to build your cartridge will be determined by experimentation and experience. That's the "Art of Reloading".

Also realize:
► The OAL shown in your load manual is not a suggestion. It is part of the Load Data used in the manual, and the lab crew is merely reporting the OAL they used during testing.

► Given: 1. All chambers are cut differently. 2. All bullet makers produce a bullet of slightly different dimensions. The inner limit Max OAL is a result of how the unique bullet fits into your unique barrel. Only the person with both the bullet AND the barrel can determine this dimension with any precision. IOW, no person here can answer your question; each individual reloader must make these measurements for themselves.

► In some special cases, a bullet-to-barrel fit may allow a Max OAL of (say for instance) 1.220”, which of course exceeds the SAAMI Max of 1.169”. In this case, the useful OAL range is then defined by the SAAMI Max as the longer limit, and then the load manual OAL as the Min OAL limit.


Hope this helps.

 

[CurryCornDog]

Thank you for the reply! A couple things, if i may ask for clarification.

Also realize:
► The OAL shown in your load manual is not a suggestion. It is part of the Load Data used in the manual, and the lab crew is merely reporting the OAL they used during testing.

I'm confused as to what this means. It is not a suggestion, but merely a report? I'm not terribly sure what the difference is. Does that make it a hard rule to the min load? An arbitrary min they figure as a "close enough/safe" min?

► Given: 1. All chambers are cut differently. 2. All bullet makers produce a bullet of slightly different dimensions. The inner limit Max OAL is a result of how the unique bullet fits into your unique barrel. Only the person with both the bullet AND the barrel can determine this dimension with any precision. IOW, no person here can answer your question; each individual reloader must make these measurements for themselves

For this I agree. I actually have calculated safe working levels, by the suggestion of other members, by figuring out case capacity by using bullet length, case length, and subtracting the difference of bullet nose to discover case/powder space. Turns out I am actually much safer at working oal than book stated min oal for an XTP bullet while fully passing plunk. And am doing so by nearly .030". That's a huge difference in comparison.

Considering these findings, your thoughts?

 

[LiveLife]

The OAL shown in your load manual is not a suggestion. It is part of the Load Data used in the manual, and the lab crew is merely reporting the OAL they used during testing.

I'm confused as to what this means.

When pressure testing is done to publish load data, actual pistols/firearms are rarely used. Instead, "universal barrel fixtures" that accommodate multiple caliber barrels are used which are single action that do not feed from the magazine.

So OAL/COL listed on published load data simply means that was the cartridge length used for pressure testing that day for the particular test barrel. But using this length does not ensure finished rounds will fit our pistol barrels nor reliably feed from magazines.

If you are loading for revolvers, you can use the listed OAL but more often, you will use the OAL that will allow roll crimp into the crimp groove unless you are using taper crimp.

But if you are loading for semi-auto pistols that must feed and chamber from the magazines, we must first determine the Max OAL allowed by the barrel then the Working OAL that will reliably feed and chamber from the magazine and this is the cartridge length we use for conducting initial powder work up. (And if the Working OAL, or rather bullet seating depth, is shorter than published, we can consider reducing the start/max charges by .2-.3 gr to compensate, depending on the difference in bullet seating depth, calculations for which we already addressed in previous posts)

And if powder charge that produces smallest groups is not at max charge and you want to squeeze a bit more accuracy, you can incrementally decreased the OAL/bullet seating depth by .005" to see if accuracy improves/group size decreases. If group size gets smaller, use the shorter OAL. If not, use the longer OAL.

These are load development steps match shooters use to determine accurate match loads. The last step of incrementally decreasing the OAL is further used by bullseye match shooters (Or those that want to pursue the accuracy rabbit hole) to where powder charge/shorter OAL results in lighter recoil loads to require reduced recoil spring rates.

An example of this is my 9mm reference load development using 115 gr FMJ RN and W231/HP-38:

• 9mm 115 gr Lead RN W231 COL 1.100" Start 4.3 gr (1,079 fps) - Max 4.8 gr (1,135 fps) - https://www.hodgdonreloading.com/reloading-data-center
• 9mm 115 gr TMJ RN W231 COL 1.135" Start 4.4 gr (1026 fps) - Max 4.9 gr (1133 fps) - https://reloadingdata.speer.com/downloads/speer/reloading-pdfs/handgun/9mm_Luger__115_rev1.pdf

• 4.6 gr and 1.150" will reliably cycle the slide and start trending accuracy of group size
• 4.8 gr and 1.150" will produce smaller groups
• 4.8 gr and 1.140" will produce smaller groups
• 4.8 gr and 1.130" will produce even smaller groups and this is my current 9mm reference load (But there are other powder loads that are even more accurate using Bullseye/Titegroup/WST/Sport Pistol/WSF/BE-86)
• 4.6 gr and even shorter 1.110" will produce comparable accuracy if savings of powder is desired (When you are loading tens of thousands of rounds, .2 gr savings per round adds up)
• I will not load 9mm with 115 gr FMJ RN shorter than 1.100" because due to tapered case, neck tension will start to decrease with shorter OAL and bullet will simply drop into the case