Author Topic: Bullets jumping crimp (Read 965 times)

swampthing · « **on:** November 25, 2005, 01:26:48 PM »

Does anyone else have this problem?:
I shoot 280g Hardcast LBT's from .44mag SRH. My problem is that when I load to velocities above 1150fps or so the remaining 3 bullets start to slip out after firing the first 3. They jump out past the crimp groove with loads around 1350fps. I've used new Remington brass, RCBS dies, and roll crimp as a final step with the seating die. I've tried varying the amount of crimp from mild to wild with no luck.
I've heard that some people have had some "bad" RCBS dies in the past, I've heard that the Redding Profile crimp die would solve the problem, It hasn't, it only lessened the degree of crimp jumping.
My expander plug was around .427" in the middle of the stem. My bullets are .432" diameter so I think there should be enough case grip. Maybe my RCBS sizer die is a little on the loose side for this application. Heard people had good luck with custom Redding Dies and Lyman M dies.
I understand that Hardcast is a popular bullet, with people shooting similar loads and never have this problem, even at 1400fps. If you do please let me know if you see something that I'm missing.
Thanks.

jar-wv · « **Reply #1 on:** November 25, 2005, 02:04:12 PM »

I had the same problem with my 454 Casull. Get a Lee Factory Crimp die and I'm betting it will solve your problem. Use the RCBS die just to seat the bullet, then use the Lee die to crimp. I use them on every caliber handgun cartridge I load for.

jar

swampthing · « **Reply #2 on:** November 25, 2005, 02:08:21 PM »

I've tried that but it swages down the lead bullets I use and affects accuracy. Thanks anyway though.

Lone Star · « **Reply #3 on:** November 25, 2005, 02:22:21 PM »

You will need to tighten your case necks. The easiest way is to use a smaller expander plug, either by purchasing one or by making your present one smaller. Measure the size of the current one, it should be ca. 0.001"-0.002" smaller than the bullet diameter to grip it tightly enough. Only run the expander into the case just enough for a minimum flair to seat the bullet. If you still have a problem, seat all bullets without crimping, then lower the die body, raise the seating stem and crimp firmly.

rvtrav · « **Reply #4 on:** November 25, 2005, 03:40:06 PM »

One techinque that I use is to just seat the bullets with the seating die. Then use the sizing die with the deprimer center removed, to "resize" crimp the case just a small amount.
You will have to trial and error test the length neccesary by pushing a seated bullet against the face of your reloading bench, usually just a 1/16" or so is all that it takes.
This is akin to the lee taper crimp techinque, but I've had no ill effects accuracy wise.
Some times "crimping the heck out of it" just crushes or bulges out the case, try some of the advice posted above, each trick may not work for everyone in every caliber and situation, but it all is sound.

Redhawk1 · « **Reply #5 on:** November 27, 2005, 01:28:52 AM »

I use the Lee factory crimp die on all my heavy recoil rounds. 44 Mag, 454 Casull, 460 Mag and my 500 Mag.

Mikey · « **Reply #6 on:** November 27, 2005, 04:43:35 AM »

Swampthing - those LBT bullets are about as hard as rocks - they should not swage down when seated into the case. I would try the Lee Factory Crimp Die. I don't know if a roll crimp will hold up to the heavy recoil, even though I crimp the snot out of my cases - but, I also run them back up through the sizing die and that seems to have about the same effect and mine do not jump the crimp.

It sounds as though your expander plug is small enough but maybe too small - do you think that is what is swaging down your slugs??? If your expander is too small, you will be forcing the slug down into the case against the case materials (natural?) tendency to tighten and force the slug back up while you are trying to seat it. The Lee Crimp die works to size down the brass against the bullet, which works against the force of the case metal trying to force the bullet out of the case from the bottom up. Also, do you expand your case far enough down to completely hold the bullet and do you open up the mouth of the case enough so the bullet can be seated about 1/4 or better into the case with finger pressure?

This is a great group of guys who have given you some very effective ways to help with this problem. One way or the other we will 'get 'r' done right. Mikey.

MS Hitman · « **Reply #7 on:** November 27, 2005, 06:56:27 AM »

Case neck tension holds more effectively than crimping does. Therefore, additional neck tension would be a benefit in this instance. Most of my .454 loads have enough neck tension to be able to discern the lube grooves on a cast bullet. These loads I am unable to pull the bullet with a kinetic puller.

Seating the bullet and crimping is best done in two seperate steps as pointed out in earlier posts.

jro45 · « **Reply #8 on:** November 27, 2005, 08:48:29 AM »

I have never had that problem. I wasn't even crimping the rounds for my S&W500 for a long time. The bullets never slipped. I just resently started crimping those for no reason. But my 44 Mag I always crimped and the 357 also.

Graybeard · « **Reply #9 on:** November 27, 2005, 09:47:35 AM »

Geez the dies are RCBS. Just call them up, explain the problem. End of problem, solution will be in the mail to you the next day. Neck tension NOT crimp is what holds bullets in cases. Sure a heavy crimp is most often called for but in reality if neck tension is proper no crimp at all works just as well. Lee has done about as good a job of brain washing folks on those dies of theirs as any manufacturer has but a good sizer die that leaves the case correctly sized for your bullet is all that's really needed.

swampthing · « **Reply #10 on:** November 27, 2005, 10:45:37 AM »

Just got back from the range with some test loads.
My bullets are at 21BHN, and are not swaged down when seated in the case, but, do at the crimp groove when LEE's crimp die is used or if I just push real hard on the ram into the roll crimp. I noticed the Redding die will shave the ogive on most loads. Bullet is .432" die is around .430" after the profile.
My load was 17.0g of AA#9 with my 280 on top. velocity is 1255. This time I tried only expanding the mouth enough to get half of the gas check in by hand, then I went very slowly in seating, also stoped every few .125" of depth to rotate the cast 180/90 degrees. Roll crimp was done last with the seater plug out and the die turned in. The first load was crimped "very" lightly, they slipped to the end of the crimp groove after 3 shots. The next batch was the same except I leaveraged the ram until I could feel the case mouth bottom out in the grooves, they slipped also but to a slightly lesser degree. Accuracy is decent, but I think the slipped bullets and non uniform crimp is letting the last 3 fly.
I hope the problem is with the dies, and them not sizing down the case enough, but these are .432" bullets.
Any body use a different brand of dies? that work for this application?
Got a feeling RCBS will tell me there in spec.
Thanks a lot for the input,
it is appreciated.
Swampthing

Graybeard · « **Reply #11 on:** November 27, 2005, 07:05:31 PM »

Quote

Got a feeling RCBS will tell me there in spec.

No they won't. They will get you one in hand that does what you want it to and at no additional cost to you. That is the one thing RCBS is famous for.

swampthing · « **Reply #12 on:** December 01, 2005, 10:18:34 AM »

It seems that the problem is with the dies themselves. I got to use my friends die set, that are the same as the ones I use, and the bullets did not jump crimp. I only got to test my 1250fps load due to time constraints. They would slip past the groove when I loaded them with My set of dies, but they held when I used my friends die set. I called RCBS and they told me that it was "highly unlikely" that I got a "defective, or oversized sizer die/dies". I explained what had happened and the guy told me that it was up to them to determine what "they" would do about it.
I will not badmouth RCBS, but I would not want to see this get ugly, especially over a $40 set of dies, what a pain in the neck.
Thanks for the insight on this problem, it is very much appreciated.
swampthing

Heavyhaul · « **Reply #13 on:** December 15, 2005, 06:17:50 PM »

Thanks Graybeard. I have always suspected it was case tention. I always wondered about crimping. I do crimp, but just enough to say I did. I always figured that if the recoil could stretch the case, that little crimp would never hold. But I'm sure no expert.

swampthing · « **Reply #14 on:** December 22, 2005, 03:18:12 AM »

Just a follow-up on the problem.
I got my dies back from RCBS, they gave me a .4285" expander plug, I will say that it made a significant difference in neck tension, and the bullets do not jump as far, but they still jump.
This time the load was with 22.5g of H110 for about 1400fps or so, just to check for jumping. the first 5 jumped a distance just dicernable with the naked eye and the last one jumped so that the case mouth was just above and inside the crimp groove. Pulled bullets are still being swaged under sized by the case inside dia. not as much, but still are.
This is a major step foward in my case/application.
I took the advice from LBT and ordered a properly sized expander plug, they told me $22. To see the difference in neck tension when switching plug diameter, from .425" to .4285", change so much, I can now see what LBT is saying about choosing expander plugs that are .0002" under bullet diameter or up to actual bullet diameter to achieve maximum case grip. Bullet will not be swaged under size and brass will have a better contact with the lead for it's entire surface, makes sense to me.
I definetaly recommend trying this if:
1. you shoot lead bullets
2. your accuracy is just O.K. {2'' at 50ydsfrom a rest, scoped}
3. your handloads are usually right next to the wall to maintain uniformity.
4. you only want to change 2 of these factors.
I'm glad I did not give up on this and go back to shooting jacketed bullets.
swampthing

swampthing · « **Reply #15 on:** December 22, 2005, 03:20:41 AM »

Just a follow-up on the problem.
I got my dies back from RCBS, they gave me a .4285" expander plug, I will say that it made a significant difference in neck tension, and the bullets do not jump as far, but they still jump.
This time the load was with 22.5g of H110 for about 1400fps or so, just to check for jumping. the first 5 jumped a distance just dicernable with the naked eye and the last one jumped so that the case mouth was just above and inside the crimp groove. Pulled bullets are still being swaged under sized by the case inside dia. not as much, but still are.
This is a major step foward in my case/application.
I took the advice from LBT and ordered a properly sized expander plug, they told me $22. To see the difference in neck tension when switching plug diameter, from .425" to .4285", change so much, I can now see what LBT is saying about choosing expander plugs that are .0002" under bullet diameter or up to actual bullet diameter to achieve maximum case grip. Bullet will not be swaged under size and brass will have a better contact with the lead for it's entire surface, makes sense to me.
I definetaly recommend trying this if:
1. you shoot lead bullets
2. your accuracy is just O.K. {2'' at 50ydsfrom a rest, scoped}
3. your handloads are usually right next to the wall to maintain uniformity.
4. you only want to change 2 of these factors.
I'm glad I did not give up on this and go back to shooting jacketed bullets.
swampthing