Crimping of Handgun Cartridges
I have loaded thousands of handgun
cartridges since 1955. Mostly .38 spec, .357 Mag, .41 Mag,
.44 Mag, .40S&W, .45ACP, 9mm. 99% were cast bullet loads.
99.99% of those loads had the case mouth crimped tightly
on the bullet.
There are many reasons for crimping:
Improves consistency of ignition
Decreases velocity variations
Holds the bullet in its proper place in the
Prevents the bullet from being forced into the
case during the feed cycle.
Prevents the bullet from being pulled out of
the case mouth by recoil
I have crimped and not crimped. I have tested for
accuracy and for velocity consistency with and without
I believe crimping of cast bullets to be
necessary for consistent performance. I have never crimped
jacketed bullets in either handguns or rifles.
Lightly crimped cases can last 40 years or more with
untold numbers of reloads. They will eventually split
lengthwise on one side ( about a half inch ). Using 40
year old cases loaded to .38 special pressures, I get
about one split case per 500 rounds. You will not know the
case split until you eject it. The split round will hit
where you were aiming and there will be no noticeable gas
The only cartridge I have found that MUST have a heavy
roll crimp is the .44 magnum used in a revolver. This is
not just for ignition but to prevent the bullets in the unfired
cartridges from moving forward under recoil and locking up
the cylinder. I have no experience with anything
larger than the .44 Magnum but this same crimping
requirement would apply to all of them.
crimps, unlike light rolled crimps, really ruin cases quickly.
In some handguns, with
cast bullets a thousandth or two oversize, or with thick
case mouths, or with a small chamber, failure to crimp can
result in a failure to be able to seat the cartridge fully
in the chamber. As well, these same issues can prevent
chambering even with a proper crimp.
In my own
apply a very slight roll crimp, (barely visible), to
revolver cartridges and a slight taper crimp, (not
visible), on autoloader cartridges like .45ACP or 9mm. To
check the crimp, try the first ten or twelve cartridges in
the chamber they must seat fully and easily with no
pressure. I field strip autos and use the barrel as a
gauge to check the crimp and overall length. ( I don't
feel comfortable cycling live ammo through an autoloader
at home.) I don't have this problem with revolvers since I
don't have to close the cylinder. If you don't have the
gun to check them, you can use a dial caliper to check the
case diameter at the mouth and immediately behind the
crimp to the case diameter measurements published in the
When checking revolver cartridges,
also check to be sure the bullet does not extend
beyond the front of the cylinder.