My proposed recipe (Newbie here!)

[Tim A Marcia]

I'm a newbie and have been working on this recipe. Any suggestions would be appreciated. I'm shooting an EMP 9mm 3".I also want to use these cartridges in my XD's (4" compact and 3" sub-compact). The EMP has the shortest working OAL and tightest chamber. This is practice ammo. None of these have been made yet. I can't find an exact recipe for this bullet so, this is what I have come up with.


CCI #500 HP-38 4.20 Berry's Plated RN 124gr. (0.356) OAL1.160
CCI #500 HP-38 4.10 Berry's Plated RN 124gr. (0.356) OAL1.155
CCI #500 HP-38 4.00 Berry's Plated RN 124gr. (0.356) OAL1.150
CCI #500 HP-38 3.90 Berry's Plated RN 124gr. (0.356) OAL1.145
CCI #500 HP-38 3.80 Berry's Plated RN 124gr. (0.356) OAL1.140

 

[funnelcake]

Assume you mean 1.1xx on the COL numbers? I’d start at 1.125 & 4.1gr.

 

[LiveLife]

Welcome to THR.

Instead of guessing for OAL and powder charge to produce accuracy, here's a better way.

When I conduct load development for any new bullet, I do the following outlined in detail in this post - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11400667

• Resize several cases and make sure they drop in the barrel chamber freely and fall out - This checks proper resizing of brass

• Measure the resized cases and use shorter length cases for dummy test rounds (No primer, No powder) - Shorter length brass allow more bullet to extend above case mouth when loaded to same OAL as longer length case

• Determine max OAL - Using the barrel and dummy rounds, starting at SAAMI max length of 1.169", incrementally decrease the OAL (say by .005") until rounds fall in the barrel chamber freely with a "plonk" and spin without hitting the rifling - https://www.thehighroad.org/index.p...rel-find-a-max-o-a-l-with-your-bullet.506678/

• Determine working OAL - Lock the slide back and feed/chamber dummy rounds from the magazine without riding it. You may need to decrease the OAL (say by .005") for reliable feeding. NOTE: While many factory barrels can accommodate 124 gr RN OAL to 1.169", due to 9mm having shorter bullet base with neck tension issue at longer OAL, many use shorter than 1.150" OAL.

• Powder work up considerations - NOTE: If your working OAL is significantly shorter than published OAL, consider reducing max charge by .2-.3 gr. NOTE: If using bullet different from published load data, reference all available load data and use the most conservative load data for initial start/max charges.

• Conduct full powder work up - Beginning with start charge, load several rounds at each .2-.3 gr increment towards max charge

• Range test - Initially, focus on powder charge that reliably cycle the slide and extract/eject spent brass. Then monitor accuracy trends as many faster powders can produce accuracy at lower charges to be used as lighter target loads. Most slower burning than W231/HP-38/Sport Pistol powders tend to produce optimal accuracy at high to near max load data.

• Fine tuning load for optimal accuracy - Once you identify the powder charge (Not at max charge) that produces smallest groups, incrementally decrease the OAL (say by .005") to see if group size decreases. Example of this is 124 gr RN loaded to 1.150" working OAL with low to mid range load data may produce greater accuracy at 1.135" due to greater neck tension for more consistent chamber pressures/more efficient powder burn.

Other considerations: Unlike many other brand plated bullets, Berry's sizes their bullets slightly larger at .356" for 9mm (Their internal testing produced greater accuracy with larger sizing) and I have gotten good results using lead load data. With regular plated bullets rated to 1200 fps, accuracy deteriorated above mid-range jacketed load data. Load data for thick plated bullets like Berry's HBRN-TP or Speer TMJ often have similar velocities as jacketed (FMJ) bullets.

• Checking neck tension and bullet setback of dummy/finished rounds - Once you determined the working OAL, perform Quality Control check to test neck tension and bullet setback. While many simply push down on the bullet against the bench top to test for sufficient neck tension, I do not believe this accurately duplicates impact force the bullet nose experiences when slammed against the feed ramp pushed by the cycling slide. Instead, I measure the length before and after feeding the round from the magazine.

• Taper crimp consideration - Taper crimp (Instead of roll crimp used for revolver rounds with crimp groove) is used for straight wall semi-auto cartridges that headspace on case mouth. Using too much taper crimp or roll crimp can reduce the finished case mouth diameter to the point where case mouth won't headspace with chamber and be inserted deeper or headspace off extractor.

Below is RMR 9mm 124 gr FMJ sized .3555" with .378" taper crimp loaded to 1.130". Note the sharp 90 degree edge of case mouth to headspace with the chamber (And note the even case neck bulge around the bullet base to indicate good neck tension and that bullet was not tilted during seating which would produce one sided bulge)

And finished rounds all showing sharp case mouth edges and even case neck bulge around the bullet base indicating bullet did not tilt during seating (Note 9mm tapered case with base larger than case neck)

• Taper crimp - Plated bullets are often made with soft lead core and use of too much taper crimp can not only cut through the copper plating but deform/reduce the bullet diameter which will decrease neck tension. Since case wall thickness at case mouth averages .011", I typically add .022" to the diameter of the bullet which essentially will bring the case mouth flare back flat on the bullet and very slightly more. So for .355" sized bullets, .355"+.022"=.377" taper crimp measure at case mouth. And for .356" sized bullets, .356"+.022"=.378" taper crimp - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10712225

• Acceptable amount of bullet setback and correcting insufficient neck tension - With longer OALs (like 1.150"-1.160") that seat bullet base closer towards case mouth where case wall is thinner (Think less friction/tension against bullet base), less neck tension is applied and after bullet nose bumps the feed ramp, could experience greater bullet setback. With sufficient neck tension, there should be no bullet setback (especially for match grade rounds). For many reloaders making general purpose range blasting ammo, bullet setback of less than .005" is acceptable but greater bullet setback indicates poor neck tension that needs to be addressed.

• Make sure you are full length resizing the brass by checking for daylight between bottom of die and top of shell holder/shell plate during resizing. If you see daylight with ram in the uppermost position while resizing a case, lower the resizing die until it barely "kisses" the top of the shell holder/shell plate.

• Use shorter OAL to seat the bullet base deeper where the case wall is thicker to produce greater neck tension. This is why increasing the taper crimp amount at case mouth won't really improve poor neck tension as friction from taper crimp is overshadowed by much greater neck tension friction from thicker case wall applying force against bullet base. In this myth busting thread, I measured case wall thickness .100" and .200" below case mouth to illustrate the difference - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713820

• Use thicker case wall brass if using shorter OAL won't resolve poor neck tension issue. Unlike most other straight wall semi-auto calibers, 9mm uses tapered case which is wider at the base. Due to this reason, simply seating the bullet deeper and deeper won't continue to increase neck tension and eventually, the bullet will simply drop down from decreasing neck tension at some point. Based on my experience with various 115/124/125 gr RN bullets, this threshold is shorter than 1.100" and I do not load 115 gr FMJ/RN shorter than 1.100". This myth busting thread post lists bullet setback amount (or none) experienced by various headstamp brass using .354"/.355"/.3555"/.356" sized bullets (Yes, 9mm bullets come sized different) - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

• Use larger sized bullets if using thicker case wall brass won't improve neck tension or thicker case wall brass is not available. This thread lists various brand and weight 9mm bullets and their sizing (FYI, some factory barrels are oversized at .356"+ and accuracy can benefit from using larger sized bullets) - https://www.thehighroad.org/index.p...re-sized-the-same.818806/page-2#post-10567453

 

[Tim A Marcia]

Assume you mean 1.1xx on the COL numbers? I’d start at 1.125 & 4.1gr.

Yes u r correct. I just fixed post. Thanks

 

[Tim A Marcia]

Welcome to THR.

You are totally approaching this the wrong way.

When I conduct load development for any new bullet, I do the following outlined in detail in this post - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11400667

• Resize several cases and make sure they drop in the barrel chamber freely and fall out - This checks proper resizing of brass

• Measure the resized cases and use shorter length cases for dummy test rounds (No primer, No primer) - Shorter length brass allow more bullet to extend above case mouth when loaded to same OAL as longer length case

• Determine max OAL - Using the barrel and dummy rounds, starting at SAAMI max length of 1.169", incrementally decrease the OAL (say by .005") until rounds fall in the barrel chamber freely with a "plonk" and spin without hitting the rifling - https://www.thehighroad.org/index.p...rel-find-a-max-o-a-l-with-your-bullet.506678/

• Determine working OAL - Lock the slide back and feed/chamber dummy rounds from the magazine without riding it

• Power work up considerations - NOTE: If your working OAL is significantly shorter than published OAL, consider reducing max charge by .2-.3 gr. NOTE: If using bullet different from published load data, reference all available load data and use the most conservative load data for initial start/max charges.

• Conduct full powder work up - Beginning with start charge, load several rounds at each .2-.3 gr increment towards max charge

• Range test - Initially, focus on powder charge that reliably cycle the slide and extract/eject spent brass. Then monitor accuracy trends as many faster powders can produce accuracy at lower charges to be used as lighter target loads. Most slower burning than W231/HP-38/Sport Pistol tend to produce optimal accuracy at high-to-near max load data.

• Fine tuning load for optimal accuracy - Once you identify the powder charge (Not at max charge) that produces smallest groups, incrementally decrease the OAL (say by .005") to see if group size decreases. Example of this is 124 gr RN loaded to 1.150" working OAL with low to mid range load data may produce greater accuracy at 1.135" due to greater neck tension for more consistent chamber pressures/more efficient powder burn.

I appreciate the info. I will follow these guidelines. Thanks

 

[joneb]

Welcome aboard Tim, this a great place for information and discussion.

 

[LiveLife]

Since many plated bullet weights can vary by 1.0 gr, I will interchange load data for 124 gr and 125 gr bullets. BTW, W231 and HP-38 are same exact powder - https://www.thehighroad.org/index.p...-different-labels.797388/page-6#post-10806193

Here are Hodgdon's lead, thick plated and jacketed load data - http://www.hodgdonreloading.com/data/pistol

• 125 gr Lead Cone Nose W231/HP-38 Dia .356" COL 1.125" Start 3.9 gr (1,009 fps) - Max 4.4 gr (1,086 fps)

• 124 gr Berry's HBRN-TP W231/HP-38 Dia .356" COL 1.150" Start 3.9 gr (920 fps) - Max 4.4 gr (1,037 fps)

• 125 gr Sierra FMJ W231/HP-38 Dia .355" COL 1.090" Start 4.4 gr (1,009 fps) - Max 4.8 gr (1,088 fps)

And here's Speer thick plated load data - https://www.speer-ammo.com/download...m_caliber_355-366_dia/9mm_Luger__124_rev1.pdf

• 124 gr Speer TMJ W231 Dia .355" OAL 1.135" Start 4.0 gr (887 fps) - Max 4.5 gr (998 fps)

Since you are using Berry's regular plated bullets sized larger at .356", I would suggest you reference more conservative lead load data or more conservative load data for thicker plated bullet (sized the same at .356") but loaded longer.

NOTE: While many factory barrels can accommodate 124 gr RN OAL to 1.169", due to 9mm having shorter bullet base with neck tension issue at longer OAL, many use shorter than 1.150" OAL.

So if your working OAL that works in both pistols comes out at 1.150", I would test 4.0, 4.1, 4.2 and 4.3 gr.

And once you identify the most accurate powder charge, I would incrementally decrease the OAL and test 1.145", 1.140" and 1.135" to see if accuracy improves. Chances are, you will find using shorter OAL will produce greater accuracy from increased neck tension.

BTW, many load 124 gr FMJ/RN to 1.135".

 

[Tim A Marcia]

Since many plated bullet weights can vary by 1.0 gr, I will interchange load data for 124 gr and 125 gr bullets. BTW, W231 and HP-38 are same exact powder - https://www.thehighroad.org/index.p...-different-labels.797388/page-6#post-10806193

Here are Hodgdon's lead, thick plated and jacketed load data - http://www.hodgdonreloading.com/data/pistol

• 125 gr Lead Cone Nose W231/HP-38 Dia .356" COL 1.125" Start 3.9 gr (1,009 fps) - Max 4.4 gr (1,086 fps)

• 124 gr Berry's HBRN-TP W231/HP-38 Dia .356" COL 1.150" Start 3.9 gr (920 fps) - Max 4.4 gr (1,037 fps)

• 125 gr Sierra FMJ W231/HP-38 Dia .355" COL 1.090" Start 4.4 gr (1,009 fps) - Max 4.8 gr (1,088 fps)

And here's Speer thick plated load data - https://www.speer-ammo.com/download...m_caliber_355-366_dia/9mm_Luger__124_rev1.pdf

• 124 gr Speer TMJ W231 Dia .355" OAL 1.135" Start 4.0 gr (887 fps) - Max 4.5 gr (998 fps)

Since you are using Berry's regular plated bullets sized larger at .356", I would suggest you reference more conservative lead load data or more conservative load data for thicker plated bullet (sized the same at .356") but loaded longer.

NOTE: While many factory barrels can accommodate 124 gr RN OAL to 1.169", due to 9mm having shorter bullet base with neck tension issue at longer OAL, many use shorter than 1.150" OAL.

So if your working OAL that works in both pistols comes out at 1.150", I would test 4.0, 4.1, 4.2 and 4.3 gr.

And once you identify the most accurate powder charge, I would incrementally decrease the OAL and test 1.145", 1.140" and 1.135" to see if accuracy improves. Chances are, you will find using shorter OAL will produce greater accuracy from increased neck tension.

BTW, many load 124 gr FMJ/RN to 1.135".

So VERY informative!!! I feel like I have a "direction" to work now! So happy I have taken on this hobby in addition to my shooting hobby! Retired and single with nothing but time and desire to excel in both! Thank U...

 

[LiveLife]

Welcome to the hobby that became a passion for some of us and congratulations on your retirement.

I too have recently retired last year and adjusting to enjoying my retirement, finally getting to work on my projects that I set aside for many years.

Since you are new to reloading, here's a great place to start off - https://www.thehighroad.org/index.php?threads/reloading-library-of-wisdom.649184/

And since barrels with different leade length (space bullet jumps from case neck to start of rifling) can require different max/working OAL, here's a listing of different factory/aftermarket barrels with corresponding max/working OAL for various bullet brand/types/weights - https://www.thehighroad.org/index.p...let-max-working-oal-col-for-reference.848462/

FYI, here's a listing of my recent myth busting threads and pending reloading projects being worked on to help with your reloading hobby - https://www.thehighroad.org/index.p...endence-from-work.853305/page-4#post-11386385

 

[kmw1954]

Hello Tim and welcome to the forum!

I have been loading 115/124gr plated bullets from both Berry's and Xtreme exclusively in my 9mm. Started with a Taurus PT92C and a Springfield XD Mod3. The Taurus I could load out to 1.175" but they won't fit into the magazine.

The Berry's 124gr RN I started at 1.160" and after getting the XD I had to shorten it to 1.150" and then tried going shorter but accuracy started to fall off. With the HP-38/W231 powder I started with 3.9gr and had to move up to 4.0gr before I would get reliable cycling and locking the slide on the last round. A this 1.150" length I was getting good results up to 4.4gr but found the best accuracy between 4.2 and 4.3gr in my guns. With the 115gr RN Berry's I am running the same length with 4.5gr of HP-38.

I have also been using AA#2 and AA#5 and a lot of Ramshot Silhouette. Recently received a HK VP9 and one of the new loads I have been working with using a 115gr plated RN and AA#2 at just above starting load level did not perform well at all, All sorts of cycling problems because I believe the load is too weak. Another load with a hotter charge worked just fine.

 

[lordpaxman]

@Tim A Marcia welcome to THR and the addiction! You’ve gotten a lot of great advice above and you’ll be getting a lot more I’m sure.
I’d recommend you take really good notes on all the reloading variations you’re doing. Just one bullet and powder combination can generate a lot of data when you vary powder and COL. And then.... there are so many powders and so many bullets after a while you’ll have a spreadsheet with a lot of rows and columns. 10 years from now you’ll want to look back and see just how some combination performed. Good luck!

 

[stillquietvoice]

My Smith has a short lead. I recently ran out of the liberty 125 lrn bullets and picked up 125 lrn bullets from State Line Bullets. The profile, ojive, between these 2 bullets are different. The liberty bullets are longer and have a defined shoulder .006 narrower at the nose. State line's have no shoulder and retain .356 further forward requiring a shorter oal 1.12 to pass plunk test compared to liberty's oal of 1.14.

Check your reloads carefully to insure function and saftey.

Welcome to the forum.

 

[Tim A Marcia]

My Smith has a short lead. I recently ran out of the liberty 125 lrn bullets and picked up 125 lrn bullets from State Line Bullets. The profile, ojive, between these 2 bullets are different. The liberty bullets are longer and have a defined shoulder .006 narrower at the nose. State line's have no shoulder and retain .356 further forward requiring a shorter oal 1.12 to pass plunk test compared to liberty's oal of 1.14.

Check your reloads carefully to insure function and saftey.

Welcome to the forum.View attachment 896681 View attachment 896682 View attachment 896684

I'm working to get my procedures correct. I made dummy rounds with this bullet for plunk (OAL) test. With Berry's 124 gr RN all three of my barrels/magazines pass the 1.169 plunk/feeding test. I'm going to start with 1.150 OAL with diff charges to find my best functioning charge then adjust OAL for accuracy. Good to know that I will be doing this work-up for each bullet that I use. Thanks for the info...

 

[Walkalong]

The EMP has the shortest working OAL and tightest chamber.

So did mine. Since they plunk ok, I would load them to fall between 1.130/1.135 OAL and see how they do. Function should be fine.

I run plinker loads with plated 124 Gr bullets in 9MM at 1050ish from a 5" 1911. 3.9/4.0 Grs N-320 depending on primer. HPs load shorter than RN, more like 1.060ish.

 

[LiveLife]

I made dummy rounds with this bullet for plunk (OAL) test. With Berry's 124 gr RN all three of my barrels/magazines pass the 1.169 plunk/feeding test. I'm going to start with 1.150 OAL with diff charges to find my best functioning charge then adjust OAL for accuracy.

Looking good so far!

While most of us already went down the path you are embarking on, it's good for you to go through the steps to learn what works and what works better.

There are good reasons why moderator Walkalong and I and many other members endorse loading 9mm bullets shorter around 1.130"-1.135" and that is improved neck tension. I didn't want to overwhelm you with more details and planned to mention this later but I think you are ready (and added to my previous post):

• Checking neck tension and bullet setback of dummy/finished rounds - Once you determined the working OAL, perform Quality Control check to test neck tension and bullet setback. While many simply push down on the bullet against the bench top to test for sufficient neck tension, I do not believe this accurately duplicates impact force the bullet nose experiences when slammed against the feed ramp pushed by the cycling slide. Instead, I measure the length before and after feeding the round from the magazine.

• Taper crimp consideration - Taper crimp (Instead of roll crimp used for revolver rounds with crimp groove) is used for straight wall semi-auto cartridges that headspace on case mouth. Using too much taper crimp or roll crimp can reduce the finished case mouth diameter to the point where case mouth won't headspace with chamber and be inserted deeper or headspace off extractor.

Below is RMR 9mm 124 gr FMJ sized .3555" with .378" taper crimp loaded to 1.130". Note the sharp 90 degree edge of case mouth to headspace with the chamber (And note the even case neck bulge around the bullet base to indicate good neck tension and that bullet was not tilted during seating which would produce one sided bulge)

And finished rounds all showing sharp case mouth edges and even case neck bulge around the bullet base indicating bullet did not tilt during seating (Note 9mm tapered case with base larger than case neck)

• Taper crimp - Plated bullets are often made with soft lead core and use of too much taper crimp can not only cut through the copper plating but deform/reduce the bullet diameter which will decrease neck tension. Since case wall thickness at case mouth averages .011", I typically add .022" to the diameter of the bullet which essentially will bring the case mouth flare back flat on the bullet and very slightly more. So for .355" sized bullets, .355"+.022"=.377" taper crimp measure at case mouth. And for .356" sized bullets, .356"+.022"=.378" taper crimp - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10712225

• Acceptable amount of bullet setback and correcting insufficient neck tension - With longer OALs (like 1.150"-1.160") that seat bullet base closer towards case mouth where case wall is thinner (Think less friction/tension against bullet base), less neck tension is applied and after bullet nose bumps the feed ramp, could experience greater bullet setback. With sufficient neck tension, there should be no bullet setback (especially for match grade rounds). For many reloaders making general purpose range blasting ammo, bullet setback of less than .005" is acceptable but greater bullet setback indicates poor neck tension that needs to be addressed.

• Make sure you are full length resizing the brass by checking for daylight between bottom of die and top of shell holder/shell plate during resizing. If you see daylight with ram in the uppermost position while resizing a case, lower the resizing die until it barely "kisses" the top of the shell holder/shell plate.

• Use shorter OAL to seat the bullet base deeper where the case wall is thicker to produce greater neck tension. This is why increasing the taper crimp amount at case mouth won't really improve poor neck tension as friction from taper crimp is overshadowed by much greater neck tension friction from thicker case wall applying force against bullet base. In this myth busting thread, I measured case wall thickness .100" and .200" below case mouth to illustrate the difference - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713820

• Use thicker case wall brass if using shorter OAL won't resolve poor neck tension issue. Unlike most other straight wall semi-auto calibers, 9mm uses tapered case which is wider at the base. Due to this reason, simply seating the bullet deeper and deeper won't continue to increase neck tension and eventually, the bullet will simply drop down from decreasing neck tension at some point. Based on my experience with various 115/124/125 gr RN bullets, this threshold is shorter than 1.100" and I do not load 115 gr FMJ/RN shorter than 1.100". This myth busting thread post lists bullet setback amount (or none) experienced by various headstamp brass using .354"/.355"/.3555"/.356" sized bullets (Yes, 9mm bullets come sized different) - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

• Use larger sized bullets if using thicker case wall brass won't improve neck tension or thicker case wall brass is not available. This thread lists various brand and weight 9mm bullets and their sizing (FYI, some factory barrels are oversized at .356"+ and accuracy can benefit from using larger sized bullets) - https://www.thehighroad.org/index.p...re-sized-the-same.818806/page-2#post-10567453

Think about it. While many reloaders obsess about producing consistent "finished OAL" yet it is truly the consistency of "chambered OAL" after bullet nose bumps the feed ramp that determines the consistency of chamber pressures produced which will translate to consistent muzzle velocities/accuracy. And these are reasons why many load 124 gr FMJ/RN to 1.135" and 115 gr FMJ/RN to 1.130" (And for me, down to 1.110").

BTW, here's a listing of bullet manufacturers and vendors THR members have used over the decades - https://www.thehighroad.org/index.p...ponents-on-sale.707473/page-178#post-11161685

Looking forward to the range report.

And as to refining shooting techniques, check these threads out:

• Neutral grip - Forming steady isometric push/pull grip that won't move the front sight when the hammer/striker is released - https://www.thehighroad.org/index.p...ith-this-glock-22.861829/page-2#post-11354420

• Neutral grip illustrated and demonstrated by Rob Leatham - https://www.thehighroad.org/index.php?threads/trigger-control.834737/page-2#post-11245649

• Trigger control - U.S. Army Marksmanship Unit, Pistol Marksmanship Training Guide chapter on trigger control - https://www.thehighroad.org/index.php?threads/trigger-control.834737/page-4#post-11320782

• Quick draw to bang as explained and demonstrated in slow motion by Jerry Miculek - https://www.thehighroad.org/index.php?threads/trigger-control.834737/page-2#post-11245640

• Point shooting - If you get bored at the range, you can consider trying point shooting using these steps - https://www.thehighroad.org/index.p...-help-me-speed-up.824618/page-4#post-10902245

Enjoy and have fun!

 

[LiveLife]

Based on our PMs, looks like you are well on your way to reloading.

I added content on taper crimp to my previous posts and want to add these further to help you with measuring - https://www.thehighroad.org/index.php?threads/measuring-crimp.860279/#post-11320703

One could get varying taper crimp measurements from the same finished round due to following:

• Worn calipers
• Inconsistent use of calipers
• Out-of-round bullet / tilted bullet during seating
• Inconsistent case wall thickness
• Inconsistent resized case length/Progressive reloading/etc.

Proper use of calipers and checking for accuracy/wear - Like using check weights for scales, I recommend use of known standards/gages for calipers especially since caliper gears can wear and loose accuracy from use. Since measuring cylindrical objects could have different "feel" depending on the amount of pressure applied to caliper jaws, I prefer to use pin gages to check my calipers with my eyes closed so I can get more consistent feel/readings (as bullets and finished rounds are cylindrical) and improper use of calipers and worn calipers will result in inconsistent taper crimp measurements.

You also want to use the same size pin gage as the items you are measuring since different parts of the caliper gears can wear at different spots. Since I mainly reload 9mm/40S&W/45ACP, I have .355"/.400"/.451" pin gages.

Pin gages can be quite affordable to have for each caliber you reload for. Here's Vermont Gage .355"+ pin gage for $4.61 - https://www.thehighroad.org/index.p...ks-for-digital-calibers.821135/#post-10545265

If you verified with pin gages that calipers are inaccurate, this could be one of contributing factors to inconsistent measurements around case neck.


Out-of-round bullets / tilted bullet during seating - Due to manufacturing process and/or shipping/handling damage, bullets can become out of round which can contribute to oblong finished rounds at case neck. And if you see noticeable bulge on one side of case neck, it could indicate tilted bullet during seating that will also elongate finished rounds and give you inconsistent taper crimp measurements around the case neck.


Inconsistent case wall thickness - Depending on headstamp, case wall thickness can vary quite a bit at case mouth on the same case where we apply and measure taper crimp. In this myth busting thread, case wall thickness was measured at 12/3/6/9 O'Clock positions .100" below case mouth above which we typically measure taper crimp and I found case wall thickness could vary by .002" to .003" - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10712225

And .200" below case mouth where most of neck tension is created from thicker case wall, case wall thickness also varied up to .002" to .003" (And BTW this why increasing taper crimp at case mouth won't significantly increase neck tension as most of neck tension comes from reduction of case neck further down from case mouth from resizing die) - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713822

So adding inconsistent case wall thickness to improper caliper use/worn calipers/out-of-round/tilted bullet can aggravate the inconsistency of taper crimp measurements.

Other factors (Inconsistent resized case length/Progressive reloading/Brass condition) - These are less of an issue but when stacked on top of other factors can contribute to inconsistent taper crimp measurements.

• While most reloaders do not trim auto-loading pistol brass, they often use mixed range brass and resized case length can vary depending on headstamp and number of firing/work hardening and this could result slightly varying amount of taper crimp applied to case mouth.
• If reloading on progressive presses, depending on the shell plate load/tilt/deflection when varying resizing effort allows daylight between the bottom of die and top of shell plate and/or cause shell plate to deflect/tilt on sub carrier, push on the station that is applying the taper crimp could vary.
• It is also my opinion that depending on work hardening/condition of brass, brass spring back could contribute to out-of-round finished case mouth/neck measurements. Measure some resized brass and see how many of them are out of round.