CRIMP JUMP

[crazyphil]

Although I have never experienced crimp jump I do have, and
carry, S&W 642 and sometimes Ruger LCR. Both under 15 oz.
I have been told crimp jump is a potential problem in these light
weight revolvers. To test I put 5 cartridges into the cylinder.
Shoot 4. Take number 5 out and compare it to a fresh one from
the box. I have also been told that it is the lighter & faster
cartridges most likely to jump the crimp. So to be on the safe
side I carry 125-Gr. & 135-Gr. I have some hotter & lighter
ammo like +P and +P+ 110 Gr. that I think I better use in my
Model 27. I wonder if the standard pressure 110 Gr. Critical
Defense would be a problem in the 2 light revolvers mentioned?
Anyone have experience with crimp jump?

 

[Arc Angel]

Properly manufactured revolver ammo should NOT experience, 'crimp jump'. The most common causes? (1) Bullets that are too loosely crimped. (2) Bullets that are crimped outside of the cannelure, or that are (3) crimped too high up on the bullet's ogive; and (4) bullets that have been, 'over-crimped' (as can happen in a Lee, 'Factory Crimp Die') to the point where the brass has been, 'sprung'; and the bullet becomes (deceptively) loose.

 

[crazyphil]

Thank you Arc Angel. Are you saying that 110-Gr. JHP +P, the Pow'RBall
100-GR. +P, and the DPX 110-Gr. (all three by CorBon) should not be
susceptible to crimp jump in the small lightweight revolvers? The two I
mentioned are both rated +P. I also have some Hornady 110-Gr. FTX
in both standard pressure and +P although there is only 95 fps difference.
The plus P (on their box) is 1,270 fps and the standard is
1,175. And finally, I have some Winchester Ranger +P+ 110-Gr. JHP.
Do you think that is significantly any more problem that the others I
have mentioned here.
Thank you for your expertise.

 

[Bastogne71]

Revolver: Smith & Wesson model 360 AirLite Sc
Ammunition: Federal AE 357 158gr jacketed soft point

Fifth round jumped crimp beyond the cylinder face and prevented cylinder rotation and also prevented the opening of the cylinder to clear the cartridge. Extremely painful to fire and unreliable with factory ammunition, it was traded off a few days later.

 

[crazyphil]

Bastogne71 so much for the theory that its the light weight high velocity
cartridges that cause the crimp jump. Did you buy the 360 new? I'm
wondering why you didn't send it to Mother Smith for warranty fix? And
I am wondering if they have a warning of any kind about ammo to use
in these little lightweight revolvers?

 

[Arc Angel]

Thank you Arc Angel. Are you saying that 110-Gr. JHP +P, the Pow'RBall 100-GR. +P, and the DPX 110-Gr. (all three by CorBon) should not be susceptible to crimp jump in the small lightweight revolvers? The two I
mentioned are both rated +P. I also have some Hornady 110-Gr. FTX in both standard pressure and +P although there is only 95 fps difference.

The plus P (on their box) is 1,270 fps and the standard is 1,175. And finally, I have some Winchester Ranger +P+ 110-Gr. JHP. Do you think that is significantly any more problem that the others I have mentioned here.

Thank you for your expertise.

Don't know! I don't have personal experience with any of the loads you've mentioned. With 110, 115, & 125 grain bullets, yes, but not with any one specific brand. I have, however, handloaded, and reloaded 10's upon 10's of 1,000's of pistol cartridges - Many of them heavily loaded; and fired from barrels as short as 2 1/2 inches.

On rare occasions I've also had a few problems with, 'bullet jump'; but I was always able to solve these problems with some sort of improvement in a sizing, or crimping/seating die. Sometimes I even had to send one of these dies back to the manufacturer in order to get it tightened up. (Only Dillon ever whined; but, eventually, they too sent me dies with the correct tolerance I asked for.)

Pistol bullets shouldn't, 'jump'; that's all there is to it! If I couldn't solve a problem like this with an adjustment to a sizing, or crimping/seating die then I'd apply some sort of asphalt, or other sealant to the case mouth prior to seating the bullet. (Which on high quality handloaded ammunition I'd probably do, anyway.) The gist of what I'm saying is that any manufacturer whose pistol bullets are, 'jumping' is - to my mind - doing something very wrong, and needs to take a long hard look at the in-house manufacturing process.

One other thing: After a lifetime of doing these things I am convinced - absolutely convinced - that an individual shooter's personal ability to fire nice tight groups, at and inside (let's say) a 6 inch circle at some predetermined distance, is far more important than whatever awesome super-duper pistol cartridge he might be using. Personally, no matter what cartridge/bullet combination I'm loaded up with, I prefer to keep my handgun target groups just as tight as I'm able; and, thereafter, I leave nature to take its course!

 

[vmumford]

Don't know! I don't have personal experience with any of the loads you've mentioned. With 110, 115, & 125 grain bullets, yes, but not with any one specific brand. I have, however, handloaded, and reloaded 10's upon 10's of 1,000's of pistol cartridges - Many of them heavily loaded; and fired from barrels as short as 2 1/2 inches.

I've, on rare occasions, also had a few problems with, 'bullet jump'; but I was always able to solve these problems with some sort of improvement in a crimping/seating die. Sometimes I even had to send one of these dies back to the manufacturer in order to get it tightened up. (Only Dillon ever whined; but, eventually, they too sent me dies with the correct tolerance I asked for.)

Pistol bullets shouldn't, 'jump'; that's all there is to it! If I couldn't solve a problem like this with an adjustment to the crimping/seating die then I'd apply some sort of asphalt sealant to the case mouth immediately prior to seating the bullet. (Which on high quality handloaded ammunition I'd probably do, anyway.)

The gist of what I'm saying is that any manufacturer whose pistol bullets are, 'jumping' is - to my mind - doing something very wrong, and needs to take a long hard look at the in-house manufacturing process.

One other thing: After a lifetime of doing these things I am convinced - absolutely convinced - that an individual shooter's personal ability to fire nice tight groups, at and inside (let's say) a 6 inch pattern at some predetermined distance, is far more important than whatever awesome super-duper pistol cartridge he might be using.

Personally, no matter what cartridge/bullet combination I'm loaded up with, I prefer to keep my handgun target groups just as tight as I'm able; and, thereafter, I leave nature to take its course!

Great info... Thanks Arc angle

 

[mazer]

Only time I ever experienced crimp jump was the first time I fired my 329PD, the rounds that I have been loading the same for years for my stealth hunter and my ruger redhawks did not work so well in the 329 (300gr SWCGC bullets)!!!
Easy fix, just had to use the 44's that I load into my leverguns (which are crimped down hard) and I was okay after that!!!!

 

[gwpercle]

Although I have never experienced crimp jump I do have, and
carry, S&W 642 and sometimes Ruger LCR. Both under 15 oz.
I have been told crimp jump is a potential problem in these light
weight revolvers. To test I put 5 cartridges into the cylinder.
Shoot 4. Take number 5 out and compare it to a fresh one from
the box. I have also been told that it is the lighter & faster
cartridges most likely to jump the crimp. So to be on the safe
side I carry 125-Gr. & 135-Gr. I have some hotter & lighter
ammo like +P and +P+ 110 Gr. that I think I better use in my
Model 27. I wonder if the standard pressure 110 Gr. Critical
Defense would be a problem in the 2 light revolvers mentioned?
Anyone have experience with crimp jump?

You tested it right....what did your test show ? Any thing jump ?

 

[crazyphil]

As I said I have never experienced crimp jump, but I have never tested
the 100 Gr. & 110 Gr. loads that I mention above. I'll try them and see
what happens.

 

[ArchAngelCD]

I have shot many different rounds in my Airweight J frames from 125gr to 158gr and none jumped crimp. I have not shot 110gr ammo, I don't like such a light bullet and see no good reason to shoot them so i can't say if they would be a problem.

 

[crazyphil]

A lot of ink has been used debating heavy & slow versus lighter and fast.
I remember years ago I noted with interest the heavy & slow 230-Gr.
Hydra-Shok .45 ACP by Federal and the lighter faster 125-Gr. Remington
Golden Saber by Remington .357 Magnum were both rated 96% in one
shot stops by Marshall & Sanow. Don't know how valid their ratings
were and haven't heard much from them in more recent years. I have
those 100-Gr & 110-Gr left over from some penetration tests I did a few
years ago. I'm going to test them for crimp jump just for the fun of it.

 

[Arc Angel]

Please be aware that I have slightly modified my second post to this thread, changed a few words and added more information.

 

[BUFF]

The amount of crimp applied at the factory can vary from production lot to production lot.

Crimp alone often doesn't hold the bullet in place. You need to have the proper amount of neck tension as well.

These are hard to do much about with factory ammo.

It is never a bad thing to buy an extra box from the same lot and shoot it in the gun you intend to carry it in to make sure it functions properly in that gun.

 

[Peak53]

I've never seen this problem with 38+P in an airweight Model 642 with factory or my handloads. But, it is something to be aware of with 357 in the bantamweight titanium snubbies - at least according to multiple threads on this forum. The gun's weight and ability to absorb recoil seem to point in that direction.

 

[buckshotshorty]

I had an LCR in 9 mm and I brought a caliper with me to the range. Almost every cylinder registered a small jump/ increase in OAL of the fifth round after 4 were fired. Not by much .02 -.03 typically.


I have Critical Defense 110 gr. Standard pressure 38 spec on order and will test them IN my LCR 38 when they arrive. I have since sold my 9 mm LCR.

 

[Rpg]

I've never seen factory ammo tie up a gun because of the projectile moving.

Handloads will do it.

Very light handguns will occasionally show this problem with handloaded ammo or remanufactued ammo.

There are limits as to pistol weight and load that work reliably.

Reducing the former without paying attention to the latter is silly.

Physics play a role in all firearms.

Ignoring physics is a fool's errand.

 

[BigBill]

For my 357 Magnum I roll a good tight crimp. Even with my hotter 44's.
I watch very carefully how much I flare the cases to start the bullet in the cases. On your pilot that flares the case mouth what diameter is the body. The tighter the better. How much cylinder to barrel clearance is there?
Nickel or brass cases? Check the I'd of the case after its resized and after its flared. Next check the OD of the bullet.

Sorry for the dumb questions I been reloading since 1975. I've had my share of problems. First I look for the root cause.

 

[ArchAngelCD]

I've never seen factory ammo tie up a gun because of the projectile moving.

Handloads will do it.

Very light handguns will occasionally show this problem with handloaded ammo or remanufactued ammo.

There are limits as to pistol weight and load that work reliably.

Reducing the former without paying attention to the latter is silly.

Physics play a role in all firearms.

Ignoring physics is a fool's errand.

Are you suggesting handloaded ammo is inferior to factory ammo? If so I strongly disagree. While some handloaded ammo could jump crimp because it was made poorly or incorrectly any handloader who know what he/she is doing will produce ammo equal to or superior to factory ammo. Your statement is incorrect and misleading.

S&W recommends you not use ammo with light bullets on their Airlite revolvers and they are talking about factory ammo. It seems the manufacturer thinks factory ammo can jump crimp even if you don't.

 

[Fishinfool]

A couple causes, I believe. In extremely lightweight revolvers, it is not so much the level of recoil, but the sharpness of recoil that leads to bullet jump. Lighter weight bullets tend to be loaded to higher velocities than heavier bullets, hence the increased sharpness, or faster speed of the recoil pulse, even though measured recoil may be higher with a heavier bullet. Think kinetic bullet puller..

Another contributing factor is probably the bullets length. Usually lighter weight bullets are shorter, and have less bearing surface, hence less bullet is being held by case tension.

Good case tension, crimp become serious factors in these light weight revolvers. No way to tell what factory ammo will or will not work properly in your gun. Just have to test whatever combo floats your boat to tell if your COAL is growing.


Larry