9mm Crimp-Jump in Revolver

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9mm Crimp-Jump in Revolver

Post by Bigtrout on Tue Aug 30, 2016 9:28 am

Now that I have a decent barrel on my 986 I'm fighting crimp-jump, a new-to-me term learned yesterday, and have run a test with dummy loads on CCI brass with 115 HAP in the last of 5 slots in the clip.  The first four being 115 FMJ factories to maximize recoil, plus I'd rather waste factories than handloads. 

I used 1.121, 1.135 and 1.151 COL's with no crimp (removed bell) and a crimp just enough to score the copper at 8X. The results follow.

COL                             NO CRIMP                           CRIMP

1.151                             1.171                                 1.179 (no mistake)

1.135                             1.148                                 1.144

1.121                             1.133                                 1.129


I don't want to overcrimp and cause deformation of the case nor do I want to change bullet profile as the 115 JHP gives me the most overall accuracy in both my 9mm's.  Not to mention I still have 3K HAP's and 1K Montana Golds.  One of my fellow 986 shooters said he used the Lee Factory Crimp Die with success.  I don't mind forking over the $ for the die but want to hear if some of you have experienced the problem and suggestions to remedy the condition.  I plan to work up some dummies incrementally increasing the (RCBS) crimp until I begin to get deformation or other visual defects.  My case neck tension seems to be adequate for the RO but the different mechanics of being captive in the cylinder during recoil needs to be addressed.  As always, thanks for any and all responses.


Last edited by Bigtrout on Tue Aug 30, 2016 9:30 am; edited 1 time in total (Reason for editing : Grammar)

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Re: 9mm Crimp-Jump in Revolver

Post by james r chapman on Tue Aug 30, 2016 9:46 am

My opinions.

1) take a factory and pull the bullet. See how heavy factory does .
2) make sure you full length resize the cases for neck tension.
3) crimp to just close the belling.

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Neck tension keeps bullets from moving

Post by 243winxb on Tue Aug 30, 2016 8:17 pm

The Lee Undersized Carbide Sizing Die 9mm Luger may help. But check the expander diameter first. Should be .002" smaller than bullet diameter.  Neck tension will be different between brands of brass, because of neck wall thickness.   http://www.midwayusa.com/product/386755/lee-undersized-carbide-sizing-die-9mm-luger

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Re: 9mm Crimp-Jump in Revolver

Post by Bigtrout on Wed Aug 31, 2016 9:29 am

A fellow 986 shooter at the range uses a Lee Factory Crimp Die and has had no jump issues.  I just ordered one on Amazon.  Until it comes in I'll shoot my RO.  If the LFC doesn't eliminate jump I'll order the undersize die.  Thanks for the expander diameter check also; I'll do that right away.  

When I began reloading last year I was getting setback in my RO.  It turns out that I was taking the RCBS instructions too literally and not camming over when sizing resulted in too little resizing.  I started pushing the handle to the bottom of the stroke and it resolved the problem.  An RCBS tech said camming over may crack the carbide...thus far after over 3000 rounds the sizing die remains crack-free.  Should this be a worry?


Last edited by Bigtrout on Wed Aug 31, 2016 9:32 am; edited 1 time in total (Reason for editing : Spelling)

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Re: 9mm Crimp-Jump in Revolver

Post by STEVE SAMELAK on Wed Aug 31, 2016 11:02 am

After a couple decades of loading, I've never damaged a pistol die (can't say the same for bottle neck cases).
As long as you aren't going crazy with the camming, I wouldn't worry.
The last bit of movement should have mild pressure not a gorilla type effort.

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Re: 9mm Crimp-Jump in Revolver

Post by Bigtrout on Fri Sep 02, 2016 3:17 pm

243winxb wrote:The Lee Undersized Carbide Sizing Die 9mm Luger may help. But check the expander diameter first. Should be .002" smaller than bullet diameter.  Neck tension will be different between brands of brass, because of neck wall thickness.   http://www.midwayusa.com/product/386755/lee-undersized-carbide-sizing-die-9mm-luger
The expander diameter is .352 and has a .355 step about .020 long before the taper begins.   I'm assuming the step is to center the case before expanding.  I also revisited expander depth steps to give me concentric bullet retention with the least depth.   That depth turned out to be my original setting. 

I loaded 30 rounds with the same component, charge and COL's I had previously used for accuracy tests in the 986 and shot 10 each of 1.150, 1.135 and 1.120 COL's but in a "single shot" configuration.   The  new groups were tighter than the groups shot previously and flyers were "less flighty" than the previous tests.  I wish I had the LFCD shipped express!   Some comments I've read regarding this problem say there is no solution that will not adversely impact accuracy.  Gulp!

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Re: 9mm Crimp-Jump in Revolver

Post by james r chapman on Fri Sep 02, 2016 3:25 pm

I don't understand,which suggestions adversely affect accuracy?

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Re: 9mm Crimp-Jump in Revolver

Post by Wobbley on Fri Sep 02, 2016 6:05 pm

The .355 step should be the expander so you can put a bullet just inside the case mouth.  So the cases should only go up the tapered portion just enough so that all your cases get full expansion.  For the 9, that wouldn't be more than 0.005.

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Re: 9mm Crimp-Jump in Revolver

Post by Bigtrout on Sat Sep 03, 2016 8:52 am

james r chapman wrote:I don't understand,which suggestions adversely affect accuracy?
More crimp with my RCBS crimp die: but my range brass length may fluctuate .008" which would yield a varying crimp-to-jacket tension.  Stay with 1.115 COL: which would not be the ideal COL for the gun.  That was the COL for the R-P factories I used in the test and they showed no movement.   Use heavier, longer bullets: which could cause even more jump, also I've settled on 115 JHP to be the most accurate at 25 yds.   Some were silly enough not to be mentioned, such as use a roll crimp.  Maybe I'm overthinking this and being too picky but even though I do not shoot competitively, my pleasure is obtaining load parameters that give me the best chance at making one big hole for all 10 rounds.  My concern is there may not be a solution that won't compromise accuracy.

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Re: 9mm Crimp-Jump in Revolver

Post by james r chapman on Sat Sep 03, 2016 11:07 am

Case length should not be a crimp depth issue with a taper crimp. A roll crimp in lead would generally be in a crimp groove.

Your on the right track load 6 and shoot 5 and measure the 6th round.

Some bullets have very little parallel bearing surface to grab. You don't want your crimp over the ogive it will cause the bullet to slide into the case under recoil.


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Re: 9mm Crimp-Jump in Revolver

Post by noylj on Sun Sep 04, 2016 12:23 am

1) Are you worried about unimportant bullet "jump?" Do your first three shots make a smaller group than the last three?
2) Do what everyone was doing until about the start of the '80s--use .38 bullets for 9x19 (there were almost NO 9mm bullets available until the S&W M39 and M59 brought popularity to 9x19. 
In your case, you could actually USE the cannelure or crimp groove to good effect--just get half-moon clips to maintain head space.
3) Folks have been roll crimping on the bullet ogive for a LONG time. With a revolver, recoil is NOT going to push the bullet into the case.

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Re: 9mm Crimp-Jump in Revolver

Post by Bigtrout on Mon Sep 12, 2016 2:56 pm

After 2 range sessions with loads using the Lee FCD I've gotten some interesting results.  My conclusion is that 9X19 mm crimp jump will occur on all 115 gr ammo and probably on all 9X19 mm ammo in general when fired in a revolver.

I tested 2 crimp die depths using four brands of range brass.  The data was taken on 2 different days of similar weather conditions with the same load configurations, brass, crimp die depth and COL the main variables.  Except for Remington 115 RN FMJ factory rounds, 4.2 Titegroup and 115 HAP were the load constants and all rounds fired from a non-mechanical benchrest at 25 yards with my S&W 986 off the same bench.

Test 1 on 9/9 consisted of 3 brass brands with dummy loads at 1.150 COL in the same clip as 4 R-P factories, COL measured before and after firing. In addition there were 10 each of CCI (Blazer) with COL's of 1.150, 1.135 and 1.120.  5 rounds fired in each of 3 targets, then repeat same loads in same targets.  Each shot was observed to determine if drifting was progressive.  It was not.  The crimp die depth was one full turn after it touched the case mouth.  I did not measure the exact depth but it created a .352 belt on the bullet.

Factory with 1.150 dummies:       CCI=1.168          WIN=1.159           R-P=1.158           

5th round in clip:                              1.150                 1.135                   1.120            
                                         1st 5      1.169                 1.160                   1.136                                                                                           
                                         2nd 5     1.178                1.152                   1.138
Group Size (10)                                2"                      2 3/8"                  2 1/8"

Test 2 today was the same except substituting R-P brass for CCI, measuring the 5th shot in a full 5 round R-P factory clip, and 1 1/2 turns on the LFCD giving a .348 belt. 

Factory with 1.150 dummies:       FC=1.162           WIN=1.169           R-P=1.165
     " 5th in clip:                        Start COL=1.112  After firing=1.119

5th round in clip:                      1.150                         1.135               1.120
                                   1st 5:  1. 161                        1.146               1.131
                                   2nd 5   1.165                        1.149               1.131
Group Size (10)                        2 3/4"                       2 3/4"               1 3/8"  8 shots 7/8"

Test 2 gave me 2 surprises, the superb performance of the 1.120 cell and the .007 jump on the factory ammo.  There were no indications of pressure increase with the maxed out crimp from test 1 to test 2 and high to low COL.  I will repeat the 1.120 cell with FC, R-P and WIN brass as variables.  I'll just save my CCI brass for my RO in which it performs very well.  Critiques and comments welcomed.

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Re: 9mm Crimp-Jump in Revolver

Post by HenryA on Tue Sep 13, 2016 3:02 pm

I'd reduced the straight part of the expander by about .001", or buy another one that is that much smaller than what you have now. I'd also only crimp enough to barely turn the case mouth. Just to "smooth out" the loaded round for easier loading.

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Re: 9mm Crimp-Jump in Revolver

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