crimping .45 rounds

[45pro]

I'm trying to decide how much crimp to put on my .45 rounds. i have it right now at .470 and the case with is micing at .474.

I measured a factory federal round and there is no crimp on it at all. Its micing at .472 at the crimp and on the case width. Why is that? Do you not need to crimp .45 rounds at all?

 

[JDubb]

just curious is this for auto or revolver firearm???

 

[45pro]

auto

 

[zoglog]

The crimp is not necessary for handgun ammunition. But it does increase the accuracy. If you want to add the crimp go for it, if not dont lose any sleep.

 

[45pro]

The crimp is not necessary for handgun ammunition. But it does increase the accuracy. If you want to add the crimp go for it, if not dont lose any sleep.

So i only need to crimp it enough to remove the flare? is .470 too much?

 

[M67]

I crimp my revolver rounds, but I've heard that crimping a 45acp for a 1911 is not necessary

 

[hps]

Flare only enough so the bullet goes into the case, not much of a flare at all!!

 

[Dave Doehrman]

I'm trying to decide how much crimp to put on my .45 rounds. i have it right now at .470 and the case with is micing at .474.

I measured a factory federal round and there is no crimp on it at all. Its micing at .472 at the crimp and on the case width. Why is that? Do you not need to crimp .45 rounds at all?

The .45 ACP head-spaces on the case mouth so rounds should not be roll crimped. A slight taper crimp can be used if necessary. The crimping feature in .45 ACP seating dies is for use with the .45 Auto Rim rounds used in revolvers.

 

[wolfman]

Yes, pistol ammo needs to have a moderate taper crimp, otherwise when it slams into the feed ramp, the bullet can be forced deep into the case, causing over pressure, and damage to the gun. Some may not agree with me, and that doesn't bother me a bit, because it's your gun in your hand. Me, I put a pretty good taper crimp on mine.

The .45 ACP head-spaces on the case mouth so rounds should not be roll crimped. A slight taper crimp can be used if necessary. The crimping feature in .45 ACP seating dies is for use with the .45 Auto Rim rounds used in revolvers.

Sorry Dave, the crimp in "ALL" pistol dies is taper, and in "ALL" revolver dies is roll. The proper type of crimp is designed into the die, a .45 acp die, has a taper crimp, not roll crimp designed into it.

 

[mike8170]

FWIW, I crimp mine down to .465, and I have not had any issues in any of my 1911's. I like the heavy crimp, especially in my older pieces, since they really slam the round in.

 

[Leadeye]

Redding makes a nice die for this.

 

[Dave Doehrman]

Sorry Dave, the crimp in "ALL" pistol dies is taper, and in "ALL" revolver dies is roll. The proper type of crimp is designed into the die, a .45 acp die, has a taper crimp, not roll crimp designed into it.

The roll crimping information came from the Lyman 49th edition reloading handbook and it specifies "The roll-crimping feature in Lyman seating dies for the .45 ACP is for use with the .45 Auto Rim cartridges used in revolvers." Evidently Lyman does produce some pistol dies with roll-crimping features.

 

[45pro]

ok thanks guys i think i'm going to stick with my .470 crimp since it seems to be a happy medium.

 

[ghitch75]

do a drop in test....remove barrel drop loaded round into chamber turn it over and if it don't fall out crimp a little more....

 

[45pro]

do a drop in test....remove barrel drop loaded round into chamber turn it over and if it don't fall out crimp a little more....

it drops out even when i dont crimp it at all. (or just enough to remove the flare)

 

[ghitch75]

it drops out even when i dont crimp it at all. (or just enough to remove the flare)

your good to go then....

 

[45pro]

your good to go then....

Cool thanks

 

[wolfman]

The roll crimping information came from the Lyman 49th edition reloading handbook and it specifies "The roll-crimping feature in Lyman seating dies for the .45 ACP is for use with the .45 Auto Rim cartridges used in revolvers." Evidently Lyman does produce some pistol dies with roll-crimping features.

Good catch, and since I don't use them, I was not familiar with the Lyman dies. After doing a little research I found this in the instructions for their dies.

http://www.lymanproducts.com/lyman/dies/pdf/dieInstructions.pdf

4. Bullet Seating
(Two-Die Sets, Three-Die Sets, and Four-Die Sets)
Figure 3 shows cutaway views of Bullet Seating Dies. This die can be
identified by the “SEAT” stamped between the knurled top and threaded
shank of the die. Note that the cartridge does not entirely enter this
die. Lyman seating dies incorporate a built-in roll-crimping shoulder
which may, or may not, be used depending upon the reloader’s preference.
The cartridge case in the illustration is shown in the non-crimp
position. Do not roll-crimp rimless auto-loading cartridges such as 45
ACP, 9mm Luger, and 380 ACP. These cartridges headspace on the​

case mouth and should be taper-crimped.

For which they will gladly "sell" you a "Taper Crimp Die" if you purchased the 3 die set, or is the 4th die in the 4 die set. Either way, to taper crimp, you have to have 4 Lyman dies.

Looks like Lyman does manufacture dies with the proper crimp built in, but they tell you about it in a back handed way, and require you to purchase an extra die to get it.

 

[Leo]

If the bullet does not have a crimp groove, do not crimp the brass. Heavy recoiling revolvers have crip grooves to keep the bullets in the adjacent cylinders from pulling OUT, not pushing in on recoil. That is a moot point in a magazine loaded semi auto. If a semi auto bullet pushes back into the case without a crimp, the full length sizing step is not being done properly. Especially semi auto ammo, just close the case mouth with a taper crimp. No worries.

 

[Aszerigan]

Just to clarify, I think you're mixing up types of crimp. There are two types of crimp, a roll crimp and a taper crimp. Revolvers (as you mentioned above) use a roll crimp to roll the brass into the cannelure of the bullet. This is essential for revolver caliber cartridges.

A taper crimp is not the same - and may be used on any semiautomatic pistol caliber, should the reloader choose to use it. Generally, when a flat bottom bullet is inserted into a straight-walled case, the reloader must flair the mouth of the casing. This is called expansion. When the bullet seating die is used, it pushes the sides of the brass back into the correct dimensions, holding the bullet in and creating more side tension.

But... there are some calibers - 45ACP being one of the most necessary - that use a taper crimp to ensure proper feeding in a tight chamber. 45ACP, 40 S&W and even 9mm all get taper crimps in my opinion, so it ensures that they'll feed in anything. Without a taper crimp, the bullet seating die may not return the brass back to its original size after expansion, and chambering can become an issue. Also, without a taper crimp, cartridges are more prone to shortening after repeated chamberings. It's not that the case was sized improperly, its that force on the bullet during insertion into the chamber can cause it to shorten - even on the first chambering.

Remember, taper crimp and roll crimp are not the same thing. One is for use on bullets with cannelures, and one is for use on bullets without. Over crimping can cause accuracy problems - but non crimping / under crimping can cause feeding issues in picky firearms.