the Ups & Downs of Crimping

[Nevada Ed]

Lately there has been a lot of discussion on what type or style of crimps is best,
or needed or even the dies to use, to get the job done for pistol & revolver loads.

For those that are new to loading or might not know of things that can happen
if the crimp or other things are not done just right, for a correct load,
here are two pictures that may help you understand what might take place.

Good luck on your future loads.

(ps, I am not fast so the 2nd picture might take a minute or so)




However;
I have noticed when loading the tall 147 gr 9mm bullet in the short 9mm case;
sooner or later, setback will stop due to the amount of powder
that is inside the case, or
the bullet, finally getting deep enough, to bind up and the case wall.

Have a nice day.

 

[stansdds]

Taper crimp does not do that much to prevent bullet setback. The taper crimp removes the flare from the case mouth, but brass is a little bit "springy",so the case mouth springs out just a tiny bit after being crimped.

The best thing to prevent bullet setback is a cannelure rolled into the case at the base of the bullet. The next best thing to prevent setback is good case neck tension on the bullet. The way to get good case neck tension is to not over-expand the case mouth.

 

[rockquarry]

Taper crimp does not do that much to prevent bullet setback. The taper crimp removes the flare from the case mouth, but brass is a little bit "springy",so the case mouth springs out just a tiny bit after being crimped.

The best thing to prevent bullet setback is a cannelure rolled into the case at the base of the bullet. The next best thing to prevent setback is good case neck tension on the bullet. The way to get good case neck tension is to not over-expand the case mouth.

I've never seen bullet setback using a taper crimp with .357 Magnum cast loads and 160 grain SWCs in a variety of revolvers. My taper crimp is not a heavy one, just enough to keep bullets in place under recoil. I can't speak for jacketed bullet loads; I haven't shot any in years and don't recall taper crimping any of them.

 

[stansdds]

I've never seen bullet setback using a taper crimp with .357 Magnum cast loads and 160 grain SWCs in a variety of revolvers. My taper crimp is not a heavy one, just enough to keep bullets in place under recoil. I can't speak for jacketed bullet loads; I haven't shot any in years and don't recall taper crimping any of them.

Bullet setback is not an issue with revolvers, it is an issue with semi-auto/full-auto weapons where the bullet hits a feed ramp during the loading cycle. Revolver ammo suffers from the opposite problem, bullet creep. When a revolver fires, the ammo recoils with the revolver and the back and forth action on the ammo acts like a kinetic bullet puller. For revolver ammo, a taper crimp may be sufficient to prevent the bullets from pulling out of the cases, but with heavy recoil energy, a roll crimp often works better.

 

[Krogen]

A good check for potential bullet setback is simply trying to push the bullet deeper into the case by pressing hard on the case head while the bullet is in contact with your bench. If it moves, you have a problem. This can be a big issue with small cases like the 9mm Lugar. Case volume is so small that slightly deeper seating depth significantly increases pressure. I convinced myself of this by running several Quickload simulations with various seating depths.

Most recently I had a bullet setback problem with 9mm Lugar and Hornady One-shot. They claim you don't need to remove it from the cases before loading. In my situation, it left case mouths so slippery that it was easy to push the bullet farther in with moderate thumb pressure on the case head. Not good.

Why One-shot with 9mm and carbide dies? It's another subject, but wet cleaning with stainless pins leaves cases so clean, they squeak. They drag on the expander plug and require more effort to size - even with carbide dies. One-shot isn't an answer for me. Car wash/wax in the cleaning "soup" may turn out to be a better answer.

 

[rockquarry]

Bullet setback is not an issue with revolvers, it is an issue with semi-auto/full-auto weapons where the bullet hits a feed ramp during the loading cycle. Revolver ammo suffers from the opposite problem, bullet creep. When a revolver fires, the ammo recoils with the revolver and the back and forth action on the ammo acts like a kinetic bullet puller. For revolver ammo, a taper crimp may be sufficient to prevent the bullets from pulling out of the cases, but with heavy recoil energy, a roll crimp often works better.

I should have differentiated between setback and creep in my post but didn't. I haven't seen creep or setback in revolvers or semi-autos. Again, I use only (my) cast bullets in handguns.

If I used jacketed bullets that are almost always smaller than cast, I might have to start over with the my crimping methods, but maybe not. Like most, I taper crimp semi-auto rounds, but I've shot a lot of roll crimped .45 ACP rounds in 1911s without problem. They're accurate, but taper crimped have been slightly more accurate for me.

I roll crimp .44 Special as I never got around to buying a taper crimp die and probably won't at this stage. Same for a couple of chamberings I no longer load for - .44 Magnum and .45 Colt. I taper crimp .45 Auto Rim cartridges, because accuracy has been just a little better.

 

[glowe]

I have used case crimp on all my reloads for the past 40 years on both taper and standard roll crimps work and if done correctly, by the instructions from the die manufacturer, they work fine. I shoot the worst culprits for bullet set-back, lever-action rifles in several calibers, 45 Colt, 44-40, 45-70 and 45-75 Winchester. Keeping the dies set at the tight side works best for me. The collision of cartridges inside the magazine tube that holds 15 rounds is huge, but have never had a problem using either crimp. I believe it is not the crimp, but the person behind the press that makes the difference.

 

[rockquarry]

I have used case crimp on all my reloads for the past 40 years on both taper and standard roll crimps work and if done correctly, by the instructions from the die manufacturer, they work fine. I shoot the worst culprits for bullet set-back, lever-action rifles in several calibers, 45 Colt, 44-40, 45-70 and 45-75 Winchester. Keeping the dies set at the tight side works best for me. The collision of cartridges inside the magazine tube that holds 15 rounds is huge, but have never had a problem using either crimp. I believe it is not the crimp, but the person behind the press that makes the difference.

Well put; the handloader makes the difference assuming he has no grossly out-of-spec dies, etc. It takes some experimentation and fine tuning to get all this right. I think many who have crimping problems may have stopped short of completion.

 

[yeti]

Roll crimp for revolvers, especially 44Mag and 347M full house loads.

I have had to use an undersize die with some jacketed 9mm bullets to keep proper neck tension with mixed range brass. Certain jacketed combinations together with some brass has required use of a U-Die. 9mm has been the worst offender, for me anyway.

The standard sizing dies work just fine for all coated, lubed and the vast majority of jacketed bullets.

 

[cmj8591]

I crimp everything except for accuracy loads for bench resting. Everything else gets some type of crimp. I have tended towards the Lee Factory Crimp dies. They seem to turn out the best and I don't like to trim my cases when I'm loading range ammo. Plus I like that final resize.

 

[sniper]

Crimp?

I have a Dillon Pro-Crimp die that does a taper crimp, then a roll crimp. It works well, and my RCBS die set does also, but a too heavy crimp can create
a barely-visible bulged case just below the crimp, which causes problems. I also have a a Lee FCD, which can resize the case and cast lead bullets, causing more problems, if care is not taken. It does take some fine-tuning as you go. Don't ask how I know this!

 

[zeke]

Alot of reloading material suggests checking for setback by using the push round on hard surface method. While this will find bullets that setback much too easily into the case, prefer the method of making a dummy round, insert in mag and release slide from full lock back. Ime, this subjects the dummy round to the forces it ill encounter when feeding from the magazine.

For semi autos that i reload with jacketed, all cases get run through a Lee U die to neck size down further. Then belled with a universal die that does not re-expand further down in the case, or a turned down expanding plug from regular belling die. Bullets are seated with a Redding comp seater that helps keep the bullets straight. Then LFC to turn remove any belling left over at the mouth.

Depending on cases/cast bullets being used, may do this for cast bullets also. In particular 200 lrnfp in 45 acp.

Certainly some may find this too much effort, but imo the main advantage the factory has is using brand new cases that haven't lost any elasticity.

In days gone by, even some factory semi auto rounds could easily get .006 in setback or more. The worst ime was the old original Rem 185 gn plus p rounds. Even the last time i checked, some factory rounds had several thousandths of an inch setback.

And while am not crimping hard enough to produce a cannelure in the bullet, factory Win whitebox rounds in 9mm and 45 acp regulary did so the last time i checked. And the only way to really check is to pull the bullet and look/measure it.

Usually it's revolver rounds that can have bullet creep, especially in ultra light revolvers with heavier bullets. But have experienced bullet creep in loading .380 acp, and certain bullets for 308 semi's.

 

[SMSgt]

Long ago I took three rounds, a Speer Gold Dot factory load, a Win PDI factory load, and one of my LRN reloads in a case with unknown number of firings, all .45 230-grain bullets. I measured the COL of each round and then cycled them through my Glock 30 10 times each and measured the COL afterwards. The reload bullet setback .010, the Speer setback .010 likewise. The Win setback .002-.003.
What does this prove? Not much except setback can happen with any round, factory or reload, to some degree.