Bullets slipping the crimp in lightweight 5-holers

[chezdog]

I wouldn't shoot aluminum ammo in any gun. I have had crimp jump lock up revolvers a couple of times. It was with heavy weight bullets in light weight guns. Revolvers can fail if you use the wrong ammo.

Because of the potential for crimp jump, you shouldn't mix different ammo in your cylinder. If you do, make sure the less powerful ones will fire first.

 

[Drail]

Try this experiment if you really believe that the crimp is what holds the bullet in the case. Look around your house and find something like a baseball bat, a rolling pin, a broomstick - whatever you got. Now, using only the thumb and first finger of one hand, hold it as tightly as you can while someone tries to pull it straight out of your hand. Can you hold onto it? Probably not. Now try it again but this time using both hands wrapped around the object as tightly as possible. Get some meat on it. I'll bet it is MUCH harder for your partner to pull it out of your grip this way if he takes it away from you at all. One hand with your fingers is the crimp. Both hands around it - is case neck tension. The crimp adds a little bit of resistance but it's not going to hold it by itself. It just doesn't have enough grip on the bullet. You're asking for a thin sliver of soft metal to do more work than it is capable of. When I seat a bullet (with no crimp applied yet) I can press the nose of that cartridge into the edge of the bench as hard as I possibly can - and it will not move. If the cartridge can't hold the bullet with only neck tension then the bullet is undersize or the case was over expanded (or both). No crimp will fix it.

 

[Master Blaster]

Yes Drail I agree with you it is case neck tension or case tension not just the crimp that holds any bullet in the case.

 

[buck460XVR]

While neck tension is an important factor in the retention of bullets in the case, so is a roll crimp, when it comes to heavy recoiling revolvers and tube fed carbines. Otherwise, why would companies put a cannelure on those bullets and why would reloading manuals put so much emphasis on it? Anyone that has reloaded for magnum handguns using slow burning powders like IMR4227 and H110/W296 knows how much difference a firm crimp makes on consistent ignition/burn and accuracy. It does this by retaining the bullet with a little more force. Many consider a firm roll crimp as important as magnum primers when it comes to igniting H110/W296 in small cases like .357. While neck tension does play a big part in retention and improper crimping can actually lessen neck tension, a proper roll crimp into a cannelure does exactly what it's intended to do.....help retain the bullet.

 

[B!ngoFuelUSN]

A taper crimp WILL NOT hold a bullet in place.:banghead: Holding a bullet against recoil inertia is NOT the purpose of a crimp. It's held in place by proper case neck tension. A firm roll crimp will help a little but it's not enough.

But I though that a taper crimp adds to neck tension by restoring the proper neck size (and thus tension) to the area of the case previously expanded for bullet seating. Wouldn't more area of brass surrounding the bullet in close tolerance be better than less?
Regardless, I've never been a fan of 9x19 in a revolver. Seems like a solution in search of a problem...
B

 

[RealGun]

Try this experiment if you really believe that the crimp is what holds the bullet in the case. Look around your house and find something like a baseball bat, a rolling pin, a broomstick - whatever you got. Now, using only the thumb and first finger of one hand, hold it as tightly as you can while someone tries to pull it straight out of your hand. Can you hold onto it? Probably not. Now try it again but this time using both hands wrapped around the object as tightly as possible. Get some meat on it. I'll bet it is MUCH harder for your partner to pull it out of your grip this way if he takes it away from you at all. One hand with your fingers is the crimp. Both hands around it - is case neck tension. The crimp adds a little bit of resistance but it's not going to hold it by itself. It just doesn't have enough grip on the bullet. You're asking for a thin sliver of soft metal to do more work than it is capable of. When I seat a bullet (with no crimp applied yet) I can press the nose of that cartridge into the edge of the bench as hard as I possibly can - and it will not move. If the cartridge can't hold the bullet with only neck tension then the bullet is undersize or the case was over expanded (or both). No crimp will fix it.

That is an admirable analogy but it seems out of place in a revolver context. A roll crimp into a crimp groove is a mechanical factor you won't get on a typical semi-auto round with a bullet that has no crimp groove. A roll crimp is not case neck tension, never mind that there is usually no neck per se. What is part of case tension is removal of the belling and expansion during the seating/crimp operation(s), but before the crimp actually occurs at the end of the stroke on the press.

 

[Drail]

Yes, but the inside dia. of the case neck still needs to be smaller than the bullet dia. BEFORE the bullet is seated. Once the bullet is inserted in the case you cannot squeeze the case down smaller than bullet dia. without swaging down the bullet. If you do that the case will spring back open a tiny bit - the bullet will not - and the fit will then be loose. The bullet's fit to the case neck dia. has to be set before the bullet is seated. The only purpose of the flare is so that you can start the bullet into a case which has a smaller I.D. than the bullet's O.D. If you seat a bullet into a case that has a smaller I.D. than the bullet dia. you will be able to see the faint bulge starting at the base the of the bullet and running the entire length of the bullet when it is seated fully - the bullet will "stretch" the case neck around it. If you can't see that bulge - you do not have sufficient neck tension. Elmer Keith used to preach this in his writings and advise handloaders to measure their expander plug and compare it to their bullet's dia. If the expander plug was not 4 or 5 thous. under the bullet dia the fit will be too loose to hold the bullet. He was right. With sufficient case neck tension no crimp is actually needed to hold the bullet - the crimp is merely removing the flare. I have had to turn down the plugs in several of my expander dies to achieve this - it makes a difference. I can load .45 ACP rounds with no cannelures and very light taper crimps and shoot them from a revolver with zero bullet pull or shoot them in a semi auto pistol with no setback (if they will feed into the chamber). A roll crimp into a cannelure is a mechanical factor - but a very weak one compared to having tension upon the entire length of the bullet. Some dies sets will fail to resize the case to a small enough dia. and then the expander will open it up too much. You really must measure your dies to know what they are doing to your cases. A lot of people tend to over flare and then heavily crimp - which simply work hardens the brass and leads to split cases. I am a big fan of the Lyman M step expander dies. They only flare a very short section of the case mouth and only enough to start a bullet. Case life is much better when using this die.

 

[Vern Humphrey]

But I though that a taper crimp adds to neck tension by restoring the proper neck size (and thus tension) to the area of the case previously expanded for bullet seating.

Wellll . . . what a taper crimp does is mostly iron out the "flared" mouth that was created to allow the bullet to seat cleanly. It keeps that flare from hanging up on the feeding ramp. If you put in too much taper crimp, you can made the case mouth too small to properly headspace.

So any increase in overall bullet pull is minimal.

 

[RealGun]

If excess taper crimp can swage the insertion length of a lead bullet, not just at the case mouth, then obviously there is an adjustment point at which the case is being tightened around the bullet. Seems the trick is finding the right point to stop the expansion removal and crimp. I think it follows that "crimp" indeed tightens the case around the bullet, that is perhaps until too much crimp is applied.

Swaging for me is caused by dies that were not intended for lead bullet diameters.

 

[buck460XVR]

I can load .45 ACP rounds with no cannelures and very light taper crimps and shoot them from a revolver with zero bullet pull or shoot them in a semi auto pistol with no setback (if they will feed into the chamber)..

But the recoil in a medium framed revolver from .45ACP is little compared to a airweight shooting +ps. Just as setback from a pistol comes from a different action than setback in tube feed rifles. Apples to Oranges. I can shoot powder puff 125 grainers in my 637 using plated bullets only removing the bell and not get bullet jump, but I cannot do it with 158s and +p loads without a good roll crimp. Same brass, same dies, using bullets of the same diameter. Again, I'm not saying that neck tension is not critically important, it is. But in many scenarios, so is a good roll crimp.