Where are crimp values listed?

[Rule3]

I have Lee, Speer and Lyman manuals. Where are crimp values listed for semi auto calibers? On the pictures of some calibers there are dimensions that I see but they are not clearly identified as to what they are?

I would like to know the crimp values for:

.32 auto
.380 auto
9mm para
40 SW
45 auto

Revolver calibers I just heavy roll crimp into the cannelure so it is what it is.

Thanks

 

[Scrapper]

Usually it's a light taper crimp as all these, I believe, head space off the case mouth. Also case length is critical here. Most of the force holding the bullet in place is the interference fit from a properly sized case.

Check me though and read manuels from many different sources.

 

[H Richard]

Those are all semi=auto rounds, and should be taper crimped about .005".

 

[aquagear]

the best way to check is to use the barrel of the caliber you are loading for .45 9mm ect. remove the barrel and use it as a gauge if the cartridge will not go into the chamber not enough crimp if it will go to far to tight. Almost all auto loading pistol rounds with straight wall cases except the 38 super (semi rimmed) head space on the case mouth, and your dies will have a taper crimp if you over crimp the round will go to far into the chamber and cause the gun to malfunction. rimmed caliber can take a role crimp to hold the bullet in place. Almost all of the good reloading manuals have a great basics chapter hat explains
reloading procedures in depth.

 

[johngalt]

There is no "crimp value". It is a trial and error process - crimp just barely enough so that the cartridge will freely chamber and drop back out again. When you get there, stop.

The purpose of crimp in an auto cartridge is to take out the flare, and nothing else. It doesn't hold the bullet in the case or prevent bullet setback.

 

[Steve C]

The purpose of crimp in an auto cartridge is to take out the flare, and nothing else. It doesn't hold the bullet in the case or prevent bullet setback.

I'm afraid this is just plain incorrect. The taper crimp on a semi auto cartridge does undead increase bullet pull and thus decreases and can eliminate bullet set back esp. when used with jacketed bullets. A simple thumb pressure test of the ammo pre and post crimp will demonstrate this if you don't believe it. Taper crimp isn't as effective with lead bullets or plated bullets in this respect though.

All factory loaded ammo in 9mm and .45 acp uses a taper crimp, how effective it is in preventing bullet setback depends upon how much it crimp is used at the factory.

I've taken factory loads that have been set back, and using measured application with a kinetic bullet puller brought the bullets back out (not quite pulled). I've then reaseated to the OAL of unused rounds and recrimped them with the Lee FC or other taper crimp die and it has completely eliminated further set back in those rounds as the same treatment did to other non cycled rounds from the same box.

 

[Rule3]

Where then did some "wise old reloaders" come up with the crimp values of say .378-.379 for 9mm and .469-.470 for 45 ACP??
I had written these numbers down from some posting here or another forum and was curious as to where they originated from.
I run everything through the Lee FCD's so have no problems.

 

[Tupperware]

I'm afraid this is just plain incorrect. The taper crimp on a semi auto cartridge does undead increase bullet pull and thus decreases and can eliminate bullet set back esp. when used with jacketed bullets. A simple thumb pressure test of the ammo pre and post crimp will demonstrate this if you don't believe it. Taper crimp isn't as effective with lead bullets or plated bullets in this respect though.

All factory loaded ammo in 9mm and .45 acp uses a taper crimp, how effective it is in preventing bullet setback depends upon how much it crimp is used at the factory.

I've taken factory loads that have been set back, and using measured application with a kinetic bullet puller brought the bullets back out (not quite pulled). I've then reaseated to the OAL of unused rounds and recrimped them with the Lee FC or other taper crimp die and it has completely eliminated further set back in those rounds as the same treatment did to other non cycled rounds from the same box.

Regarding crimp, I believe johngalt is correct with the following statement:
"It doesn't hold the bullet in the case or prevent bullet setback."

A semi-auto case is taper crimped to remove the flare left by the expander yet leave the case mouth available for headspacing purposes. The critical component is the reloading equation is the often overlooked expander die.
A properly sized case that is then properly expanded will provide sufficient neck tension to prevent bullet set-back, crimp has little to do with it.
Over crimping jacketed rounds does very little to decrease bullet set-back or increase neck tension. You made this point yourself when you mentioned that "taper crimp isn't as effective with lead bullets or plated bullets". The reason for this is that lead is inelastic, while the copper jacket is slightly elastic and the brass case even more so.
If you over-crimp a plain lead bullet all you are doing is displacing the lead. Neck tension will barely increase and can, in some cases, decrease. When you over-crimp a jacketed bullet, you are also compressing and displacing the lead inside, only you cannot see it. In extreme cases accuracy can be affected or the jacket can separate from the bullet.

 

[Tupperware]

I've taken factory loads that have been set back...............

Just curious, do you know the reason the bullets set back originally? Was it bad ammo, or some other reason?

 

[Skip Sackett]

No, a taper crimp, if applied correctly will allow the cartridge to headspace on the case mouth and hold the bullet in place to keep bullet setback from happening. Look at this picture and notice the bullet on the right. It was pulled from a 45ACP case that was crimped to .470" or so.

Notice the ring around the bullet. With a taper crimp applied like that, it will prevent bullet setback AND still allow the case to headspace correctly. Not applying a taper crimp to SOME auto ammo will get you a KB if you aren't careful. 40S&W comes to mind. Case/bullet tension SHOULD hold the bullet pretty tight, no question about that, a taper crimp is a must when you want target accuracy and 100% functionality.

The best thing to say about where to find it is, your firearm. It will tell you via trial and error or as a case gage. The amount of crimp that gives you the best results is the right one for you.

 

[Rule3]

Skip (Smith Crazy) You bring up my exact question. Where does the .470 come from? I have seen and heard that from many 45 ACP shooters some of them who(whom?) shoot competitively.

 

[running iron]

Actually, .473 is max for a taper crimp on the 45 acp. I use .471. If you go much tighter, on some brass, you will make the bullet smaller than need be. I have pulled bullets that were crimped too tight and they just fall into a new case and are too small for accepted accuracy.

 

[RidgwayCO]

Short answer, OCD1: crimp values are not "listed" anywhere (or at least anywhere I've ever been able to find).

Some reloaders have standardized on measurable crimp values that work for them. Personally, I've never measured a crimp in my life. My semi-auto rounds are taper crimped just enough to remove the case flare, relying on a proper case-bullet tension to hold the bullet in place and prevent deeper bullet seating on feed. My revolver rounds also rely on this case-bullet tension, but are roll crimped with varying amounts of force (light, firm, and heavy). These roll crimps are used primarily to help prevent bullet pulling from recoil. Some people also use the heavy roll crimps to give the slow burning pistol powders a little more time to build up pressure.

Please don't ask me to define my roll crimp terms, as that would like trying to define pornography... I can't define it, but I can tell you when I see it...

 

[Rule3]

Short answer, OCD1: crimp values are not "listed" anywhere (or at least anywhere I've ever been able to find).

Some reloaders have standardized on measurable crimp values that work for them. Personally, I've never measured a crimp in my life. My semi-auto rounds are taper crimped just enough to remove the case flare, relying on a proper case-bullet tension to hold the bullet in place and prevent deeper bullet seating on feed. My revolver rounds also rely on this case-bullet tension, but are roll crimped with varying amounts of force (light, firm, and heavy). These roll crimps are used primarily to help prevent bullet pulling from recoil. Some people also use the heavy roll crimps to give the slow burning pistol powders a little more time to build up pressure.

Please don't ask me to define my roll crimp terms, as that would like trying to define pornography... I can't define it, but I can tell you when I see it...

Thanks. I do not measure mine either but as I said , I read some data somewhere as also mentioned in this thread on the 45 ACP at such and such length with a .470 taper crimp. So then I figured I should be measuring after I set my dies, After running 45's through a LFCD, it does come out right at at .470 or so.

On revolvers, I have the same system as you. I just roll it into the crimp groove till they do not move.

 

[Skip Sackett]

I think the only place that I ever heard of measuring crimps was here and it way by Sgt. Preston and others about their 45ACP loads.

I measured some after that and then just went back to making them work!

Use your barrel as a case gage. Make up a dummy round and paint the end blue or some color of your wife's fingernail polish and keep adjusting the crimp until the case head is too far in the chamber. Go a little at a time on the die so you can judge when too much is too much. Then you will know the measurement that is too much for your chamber. Bigger than that but with all of the belling removed is the biggest you can go.

Like Ridge said, just enough and not too much!

It is firearm, and maybe discipline specific. IDPA ammo may not need to be all that accurate while Bullseye ammo does.

I guess the real answer is, there is no specific answer other than what works in your firearm.

Wish I could be more help Roy.

Did you ever shoot those bullets?