How to solve Crimp Jumping for large caliber guns?

Arthury · Jun 7, 2012

Large caliber magnum revolvers produce heavy recoil. Consequently, the cylinder experience a "pull" during the discharge and the remaining bullets will slide out of the cases just a tiny bit. Subsequent discharges induce the remaining bullets to slide out further. This is called Crimp Jumping.

For a discussion about Crimp Jumping, look here:
Ruger SRH Alaskan In .454 (Crimp Creep Test)

I am assuming this phenomenon probably occur in the 454, 460 and SW500 cartridge. I did not hear many people complain about it in .44 mag.

Under certain circumstances, like using heavy bullets with full load magnum, the final couple of bullets still in the cylinder may protrude so much that the cylinder becomes locked. What are your thoughts about this and how do you solve this pertaining to self-protection revolvers in the woods?

CWH44300 · Jun 7, 2012

Some loads in my 329 would jump, had switch out a few seating dies until I found one that worked, an old Lyman set that I've had for years(pre carbide)

RobsTV · Jun 8, 2012

Gave up and just live with it on a 500. Used Lee seat/crimp die. Used Redding Profile crimp die. Tried crimping in separate steps. Tried combinations of above. The best results were seat, then profile crimp, then back to seat/crimp die for a second and final crimp. Bullet still moves a little though... Have tested hard enough crimp that it buckled cases with both the Lee and Redding dies. Have tried with almost no crimp. And, everything in between.. Now the disclaimer is, depends on the bullet. All of that was with latest version of Berrys plated bullets (even crimped to the point of buckling cases could never tear the plating on these new bullets). When used with Remington Core-Lokt w/cannelure, they did seem to hold pretty good. But for 20 cents a bullet, I'll make the Berrys work.

ImprovedModel56Fan · Jun 8, 2012

I first had that problem with a Charter Arms Bulldog and factory ammo. Solved it by reloading with a jacketed bullet with a crimping band, and put max crimp on it with a conventional crimping die.

bigmoose · Jun 8, 2012

It can happen with lighter loads also. A single action .45 Colt of mine had this occur with range loads. I thought the slight crimping I applied would hold the bullets from backing out, but it didn't. I now positively roll crimp into the cannelure. No problems since. As alluded to, closely watch for the sixth round. This is the cartridge that has experienced 5 blows of the "revolving bullet puller".

67tempest · Jun 8, 2012

I roll crimp my loads instead of taper crimping them. If the cannelure or lube groove is in the correct spot and you roll crimp the case mouth into this groove you should have no problems. I picked up a crimp die for use on my .223 loads, actually crimps the case mouth into the bullet. Most military ammo is crimped in order to insure the bullet doesn't pull out and disable the firearm. Read several different articles regarding crimp dies and the general thought is the crimp has little or no effect on accuracy.

Arthury · Jun 8, 2012

What about factory loads, like bear loads? Are the reputable brands (e.g. Garrett, Buffalo Bore, Grizzly) safe enough to last 5 rounds of recoil?

Also, it appears that a few factors can help mitigate the crimp jumping issues:

increase the weight of the gun and/or barrel
introduce ports/compensator/muzzle-brake which are angled rearwards

The above inadvertently damps the rear-facing recoil and as a good side-effect will also tame the crimp jumping.

DonD · Jun 8, 2012

After 9 yrs of reloading for and shooting several .500 Mags, I've never had an issue with slugs jumping the crimp. I have used RCBS dies exclusively. I seat in one step and crimp in another. Hasn't been an issue for me.

I will say that 99% of my reloading is for cast slugs, moderately hard for plinking loads, hard cast for heavier loads, all of them have crimp grooves. Don

buck460XVR · Jun 10, 2012

DonD said:
After 9 yrs of reloading for and shooting several .500 Mags, I've never had an issue with slugs jumping the crimp. I have used RCBS dies exclusively. I seat in one step and crimp in another. Hasn't been an issue for me.

I have to say the same for me and reloading for my .460. A heavy roll crimp into the cannelure with standard RCBS dies. I have yet had a bullet jump crimp so as I could notice any difference. I have had problems with it in my 637 Airweight and plated bullets without a cannelure to crimp into.

kennyb · Jun 10, 2012

same here...RCBS no jumping on 44mag,460mag,500 mag.etc

tkosiba · Jun 10, 2012

Simple. Enhanced accuracy (especially using lead bullets) comes from separate seating and separate crimping.

I use a separate Redding Profile roll crimping die on "all magnum revolver calibers." Never a problem on bullet movement with enhanced accuracy. Besides, when they cost so much, why not get the added benefit with one additional step?

Enframe · Jun 10, 2012

Agree with the other guys, less powder, more crimp, in two steps.

I've never had a problem with crimp jumping. But then, my heaviest caliber is .44 mag, with 240 grain or less bullets, and never over max published loads. YMMV.

RobsTV · Jun 11, 2012

Something no one has mentioned that might be affecting some is the cases used. As mentioned above, a little bullet creep was never eliminated for me, no matter what type of crimp was used (berrys plated bullets with crimp groove, crimped in 3 seperate steps of seating, Redding Profile roll crimp, and lastly Lee Taper crimp, worked best).

But, I am using S&W 500 Starline Nickel plated cases with moderate 350gr 1650fps loads (extra thick plated bullets rated at 2000+fps), which is much hotter and tougher on crimp than any 44 magnum hottest loads for comparison. Perhaps the Nickel cases hardness (or lack of?) might be contributing to creep.

David LaPell · Jun 11, 2012

I always given my heavier loadings a good roll crimp and I too think that it works best if done with separate dies although I have had really good luck with Lee's dies. I have never had issues with any of my hotter loads jumping crimp but I use pretty much all cast bullets with crimp grooves.

Kinman · Jun 11, 2012

I first experienced this back when I first started reloading with an old Ruger 3 screw .44, had one of those little RCBS presses and found that I needed to seat the bullet to proper depth on one pass, then go back and set the crimp firmly on the second step. Once I did that I never had any further problems, this became second nature to me and since I enjoy the time I spend reloading I continue to do it this way to this day, just as with any rifle cartridge. I still weigh every charge for rifle and often for my pistol cartridges that are intended for hunting or self defense.

J-FRAME · Jun 11, 2012

Roll crimp two die seating and crimp- no problem but always check them cause it will tie up a revolver .

Ivan the Butcher · Jun 12, 2012

Corbin used to make a cannalure tool, so you can decide where to crimp the bullet. Also a commercial reloader friend of mine uses that same tool make a cannalure at the base of the bullet on loaded ammo for tube magazine rifles (lile 30-30 or 45-70) to keep from pushing bullets deeper. I think they still sell that tool. Also most factory ammo is sealed at the prime and case mouth, which keeps water out and glues the bullet in place- you could expairment with finger nail polish. I'd say use quick dry and let dry a few days-no air can get to it once crimped. I also saw an add for primer sealer in the gun rags once.

Shuz · Jun 12, 2012

I had this problem with the hard recoiling 329PD. I solved the problem by using a smaller expander plug in my Square Deal B powder die. This in effect, increases case neck tension. I believe this is far more important than style or amount of crimp.

Neumann · Jun 12, 2012

I use a roll crimp in a separate operation from seating, with RCBS or Dillon dies. I've never had a problem with creep, but then I use jacketed bullets with a cannalure (mostly Hornady XTP).

BruceM · Jun 12, 2012

had this problem with the hard recoiling 329PD. I solved the problem by using a smaller expander plug in my Square Deal B powder die.

It's amazing that people don't realize that the last line of defense in preventing bullet jump(revolvers) or setback (in autoloaders) is the crimp. If you are having issues with the bullets moving, about 90% of the time it's because the expander is too big. About 5% of the time, it's because the sizer is too big. The remainder have to do with crimp or a combo of one and two. This also applies to wide velocity swings with propellants like H110/W296. You need to have both a good, heavy crimp and high neck tension to prevent bullet movement and promote a complete burn BUT the neck tension does, by far, the major amount of the heavy lifting. I believe that people look to crimp first because it's the easiest thing to tinker with but note the less than acceptable results noted in previous comments!

Bruce

How to solve Crimp Jumping for large caliber guns?

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