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View Full Version : Need more help men, 9mm



Harpman
01-29-2008, 08:47 PM
Reading the reloading manuals, they say no crimping the 9mm, becasue it head spaces on the mouth of the case, but the dies come with a crimp built in the seating die....should I do a light, heavy or no crimp ?

swabbie
01-29-2008, 08:52 PM
you will need a light taper crimp to prevent the bullets from going back into the case in most semi autos

38 Super Auto
01-29-2008, 09:13 PM
When you load rounds for autoloaders, you need very little crimp. I adjust the crimp die down until the mouth flare has been eliminated, and then I crimp just a little more.

I suggest examining some factory loaded rounds to see what a factory crimp looks like compared to your handloaded ammo.

I'd recommend getting a case guage from Dillon or other. You drop the loaded round into the case guage, and the round will "chamber" if the case was sized sufficiently, the bullet is crimped sufficiently, and the bullet is seated deep enough. At about $10, I think it's a good investment.

There's also the Lee factory crimp die. I use these for all my auto loads.

You should also remove the barrel from your gun and verify the rounds will chamber properly. This is a good idea before you load up a quantity of ammo.

35remington
01-29-2008, 09:43 PM
It is very likely your 9mm dies have a taper crimp built into the seating die rather than a roll crimp. Check for a crimp shoulder in the seating die. If you don't have one you probably have the taper crimp feature.

A taper crimp is appropriate for autoloading pistol cartridges but can be overdone. I don't particularly care to crimp the case and seat the bullet in the same step as it is squeezing the bullet as it is being seated, which isn't particularly good for the lead bullet.

In a worst case with a heavy taper crimp this scrapes off bullet metal and bullet lubricant (tumble lubed bullets) ahead of the case mouth, which isn't good for reliability, accuracy or headspacing. If you have another die station available on your progressive or are loading one step at a time separating crimping and seating the bullet is best IMO.

Turn the case in to remove the flare completely and very little to no more. Taper crimping does not help to hold the bullet more firmly in the case - only friction between the case and bullet does that. Taper crimping is a reliability aid.

9.3X62AL
01-29-2008, 09:43 PM
The "no crimp on autopistol ammunition" rationale has its roots in the manner in which many autopistol cartridges fit themselves against a positive "stop" within the chamber, sometimes called "obtaining headspace". 380 ACP--9 x 19 Luger--357 SIG--40 S&W--10mm--and 45 ACP use the case mouth edge to achieve this "stop", and there is a belief that a pronounced roll crimp on such an autopistol cartridge will compromise this process.

Older RCBS seater dies for 9mm and 45 ACP had a roll crimp shoulder, and I used this shoulder successfully to just straighten out the flare. I bought separate taper-crimping dies, and still use this fourth die/station when loading autopistol cartridges and applying a taper crimp.

Newer RCBS die sets have a taper-crimp seater die. I still seat in one step, and taper crimp in another. Why? Because seating a bullet while compressing the case sidewalls with inward force causes inconsistent seating depth/overall length, and with cast boolits can cut a divot into the boolit sidewall. End-on force like that imparted by a roll crimping shoulder does not cause these anomalies.

MtGun44
01-30-2008, 02:21 AM
Taper crimp, and I prefer a separate die, not the combined seater-crimper,
but you can usually get decent results from the combined die.

The most common reloading problem with .45ACP that I have seen with new
reloaders for IPSC has been failure to taper crimp or not enough taper
crimp. I have had far less exposure to the 9mm and as the case is significantly
tapered itself, it may be less sensitive for feeding to having a proper taper
crimp than the .45ACP is.

Bill

Leftoverdj
01-30-2008, 02:36 AM
There's a lot of voodoo here, and I don't claim to know the answers. I do know that .45 ACP cases still work fine when they are way under the claimed minimum length, and 9x19 ammo functions perfectly through my Star B in 9mm Largo. I suspect that in those instances the headspacing is set by the extractor 'cause they sure ain't headspacing on the case mouth.

I only shot a couple of clips of 9x19 through the Largo 'cause I suspect it would be a long term stress on the almost irreplaceable extractor.

Bob Jones
01-30-2008, 02:38 AM
Everybody gave you good advice, but just to put it in the simplest possible terms, because it confused me when I started...

Straight wall rimmed cartridge cases for revolvers (.357, .44, .45 Colt, etc.) are "roll crimped", meaning that the last bit of the case is turned inwards, usually into a crimp groove. This holds the bullet in place very firmly for those high recoil loads.

Rimless autoloader cartridges (9mm, .40, .45ACP, etc) are "taper crimped". What this really means is that when you resize the case you resize it smaller than the bullet so that the bullet is squeezed by the walls of the cartridge case, that is what holds the bullet in place, not any "crimp". In order to load a cast bullet you need to bell the very end of the case so that the soft lead bullet will slide into the case. The process of taper crimping just removes that flare so that the outside of the case is smooth and straight, it doesn't do anything to hold the bullet in place, that is done by the tension of the cartridge walls.

Measure a factory cartridge right at the end of the case. For example, off the top of my head, my 9mm cases are about .377. Adjust your taper crimp die so that your reloads are about the same as your factory load, plus or minus a couple of thousandths, and you should be good to go.