44 Cast Bullet Question

[mdi]

Theoretical Question;
I reload .44 Magnun rounds with 2400 and a cast 240 gr. Beartooth bullet. I use a heavy crimp. So my question is, does a heavy crimp (or any crimp) reduce the diameter of the bullet on firing? I can visualize the brass "sizing down" the OD of the bullet as it leaves the case. Even if the brass is more elastic than the lead, I would guess there is some reduction in the diameter of the bullet upon firing. Even if the reduction is as little as .001" that "may" have an effect on accuracy?

I've been looking at cast bullets and find many have a very small band in front of the crimp groove. If that band remains full diameter and the rear bands are "swaged down" by the crimped brass would the bullet have a tendency to "tip" in the bore?

I know these Q's have little to do with practical everyday reloading, but I was just thinking (that used to get me in trouble a lot, so I stopped). You know; "Enquiring minds want to know!"

Thanks,
Mike

[jhalcott]

  I don't think so! The brass will expand to the cylinder walls,the pressure on the base of the bullet SHOULD cause it to "obturate" to fill the bore as it goes down the barrel.

[Gavinator]

 If you have a micrometer and an inertial bullet puller, you could compare a loaded and crimped bullet to one that has been loaded and not crimped.
 I'd also measure one of the bullets that has not been loaded, and see if the brass tension on the bullet is changing the diameter (which I don't think it will).

 If you think you're getting poor accuracy you should make sure the cylinder throat diameter is larger than the groove diameter in the barrel.

[Travis Shuck]

Unless you are using a taper crimp die, the crimp should just be rolling the top edge of the case into the canulure.  Measuring one that has been pulled with an inertia puller would not be the same as one that is fired, because the pressure upon ignition would blow the brass out against the walls of the cylinder(as was already stated)  leaving the bullet free to leave.

[gypsyman]

I agree with jhalcott on this one. Both brass and lead are easily malleable,(soft). When the pressure of the powder is building, the brass swell out, and the bullet obturate's,squish's out, to ''grab'' the lands and groove's. What will mess up accuracy more with a cast bullet, is if the base of the bullet has a defect in it. I cast my own, but have heard nothing but good on the beartooth bullets, so you should be good there. gypsyman

[Blammer]

basically, lead bullets will obturate when fired.

They will "slug up" to the barrel. This will occur some while in the case.

Your small crimp into the bullet will not affect performace of the bullet. Crimping will affect how the powder burns. Nice crimp will give nice consistent powder burnings.

Other factors more important w/lead bullets are...

sized bullet dia, vs dia of barrel, seating depth, how much crimp, and the usual variances of loading your own.