CRIMPING -( TO CRIMP OR NOT TO CRIMP )

Unless you're going full auto, any crimp in a 9mm is pretty much overdoing it.

 

On 9mm and 45 acp I use the Lee factory crimp and sizing die . Seems to insure flawless function . Most 45 acp and 9mm bullets I come across don't have a cannelure .

 

For 25 years I’ve always used a slight taper crimp on all auto cartridges,
and I’ve never had issues. I find OAL is a more critical factor.

 

Forgive me but as I recall Swaged Bullets had a Wax Ring where a Cannelure was found on USGI 5.56 rounds to make the bullet tumble and break apart on impact causing more interior damage to tissue on impact.

Karsten

 

Been reloading since the 70’s and the above is correct. The crimp does not hold the bullet, a properly sized case does. Probably removing the flare is really all that we are doing. I’m at about .377-.378 for 9’s and .470 for 45’s.

 

Revolvers need a roll crimp (where the case mouth is turned into the cannelure) since the recoil action tends to pull the bullet out of the case.
Semi-autos don't have this recoil impulse, with feeding being the action that can push a bullet into the case. Since the case is supposed to head-space on the case mouth, you DON'T want a roll crimp, just a taper crimp. The taper crimp is really only there to remove any case mouth flare and NOT to hold the bullet--it is really just a feed-and-chamber issue.
Best thing for a semi-auto is to immediately try to push the bullet deeper in the case with thumb or finger pressure and reject any rounds where the bullet moves even slightly. Then, just taper enough so the rounds all chamber. If you look at factory rounds, you'll see the case mouth is just straight and NOT turned into the bullet at all.

 

Do you have a crimp die? If so which one do you have?

 

What Dwe said

 

Dillon makes the taper crimp dies I’ve been using.
Dillon die sets include separate seating and crimp dies.

 

Trying to figure out if the OP has a roll crimp or taper crimp die. Or even a crimp die at all. I have a Dillon taper crimp for 9mm and a Redding taper crimp for 45acp. Both for my 550 and Redding T7.

Crimping is probably the easiest of all my dies that I set.

 

I'm a big fan of the Lee Factory Crimp Die (FCD) for both revolver and auto-loaders.

For auto-loaders I put in just enough taper crimp to remove the case flare and to reliably pass the plunk test on my tightest barrel.

 

I put a slight taper crimp on 9mm and .45. It seems to help with feeding.

 

My "crimp" die on my 550 is set to give me .470 at the case mouth. Basically removing the bell. Zero (0) feed issues in my Colts or my Baers.

 

Yep, agree with the Lee factory crimper. It does add another step, but I use a single stage anyhow, so...
Never have a problem with just a slight crimp, and a proper coal and properly sized case is critical. The Lee crimper just makes it perfect, IMHO

 

I crimp all my 9mm rounds.

 

Not passing judgement here, but I am on the lazy reloader side and taper crimp with a Dillon taper crimp die just enough to remove any bell mouth and that seems to be about .469-470 with an occasion round going to about .471 on the calipers. Some of the B/E shooters over on "Bullseye-L-Forum" believe that crimp plays an important role in accuracy and crimp down to about .465-.466. I believe that the late great gunsmith Jerry Keefer was one of those that believed in a heavy crimp for accuracy and did some experimenting accordingly. This line of thinking is probably predominant among the lead shooters.

 

LOL no -- have no idea where that one came from....

Not even possible with FMJ in that round to make it "break apart". Pretty funny the wild things people put on the internet.

Read this for some background in military ammunition. It is a pretty good summary of how the requirement for FMJ initiated from and where it is today. The new Sig striker pistol for the military has as part of the contract to supply ammunition and it is hollow point. On rifles the JAG made a ruling that the SMK HP was not a expanding by design hp and as such was compliant. One reason you will never see in writing by Sierra anything that states the SMK is anything but a target bullet. They sell a lot of bullets for loading into ammunition for the military.

https://www.icrc.org/eng/assets/files/other/irrc_849_coupland_et_loye.pdf