Crown

ChetStafford

If a rifle has a feild grade crown in it how much difference would it make to have an 11 degree target crown put in the barrel? just a thuoght I have always owned a lot of rifles but never changed anything about any of them. does a match grade crown have a differnt twist rate the a standard crown?what is the real difference[?]

sandwarrior

csjs1194,

The crown is a 'counterbore' to protect the rifling. It has nothing to do with twist except you would have a target crown on a barrel that uses a different twist than what you would use hunting because you use a specifically different bullet.

Highball

Crowns are a continuing debate ..this angle versus that angle.
The important thing is that there be no damage at the muzzle...re-crowning often actually really helps.
Also...many factory crowns are cut at an oblique..the perfect crown is cut at 90 degrees to the axis of the bore..this is CRITICAL..the purpose being, as the bullet exits from the bore, the gases behind the bullet are traveling faster then the bullet..and the gas needs to EVENLY escape around the base of the bullet.
This prevents upsetting the bullet.

Often, you can look at the muzzle streaks left by gases after several rounds have been and actually see heavier deposits on one side then the other.

temblor

quote:Originally posted by csjs1194
If a rifle has a feild grade crown in it how much difference would it make to have an 11 degree target crown put in the barrel? just a thuoght I have always owned a lot of rifles but never changed anything about any of them. does a match grade crown have a differnt twist rate the a standard crown?what is the real difference[?]

If your field type crown is cut straight and the gases are exiting equally around it wouldn't make any difference.
If your current crown is cut crooked a new crown job could help alot.
The crown job has nothing to do with the barrels twist rate. That refers to the rifling grooves cut inside the bbl.
Only real difference is the angle that it is cut ( ie: straight vs 11 degree for example) and the amount that is recessed.

ChetStafford

thanks a lot guys I went from 1.25 inch groups with factory ammo down to .80 groups with my hand loads[:D] and was trying to think of any thing that might tighten it up a little. the gun is a 300 weatherby mag I think maybe I can play with my loads and get a little more out of it I am shooting barnes 180gr xlc bullets over 84.5 grains of rl22 in a weatherby case with a federal 215 primer over all case lenght is 3.610 this is a maximum load in the barnes book but i am showing no signs of pressure.

nononsense

csjs1194,

You might try switching over to the Triple Shock bullets which have been more accurate than the XLC's in my hunting rifles. Barnes is in the process of phasing out the XLC bullets anyway in favor of the Triple Shocks and the new MRX bullets.

Best.

JustC

the angle of the crown has been found to mean very little if anything. It is the fact that it is cut perfectly perpendicular to the bore to vent the gasses in such a way as to apply equal forces on the entire circumfrence of the bullet base. I have read about studies that prove as long as it is concentric, the angle is a non-iisue. I have various angles and have not seen any differences.