.308: inside and outside chamfering

[Campbell]

I have taken delivery of an RCBS Trim Pro 3 Way Cutter.

I have acquainted myself with how to adjust the tool, but I don't know how much chamfer to the outside and inside of the case should be given.

Please will someone give me some guidance.

Many thanks in advance.

Cam

 

[JohnKielly]

After trimming the case to length, chamfer the outside so there's no material overhanging the case neck. Chamfer the inside enough to break the square edge of the case and smooth it up so the bullet seats smoothly. With virgin brass, just chamfer inside but only if you have some tool that can ensure that the case necks are round.

 

[Sniper338]

Yep. ^^^

there isnt a exact measurement... its to each their own in the end... outside just needs enough to deburr, inside needs enough to push in a bullet and not goober up the jacket on the bullet.

I use the wilson case trimmer micrometer, and deburring tools for it... try to get them all pretty exactly the same..

 

[Trevor60]

When you trim brass (trimming only) the brass can look like the attached middle case

When you Chamfer you are trying to trim the rough brass to clean both outside and in. the outside Chamfer is to avoid the rough brass edge from rolling over into the neck and the inside is to smooth out the transition for bullet seating... the middle two are the best of the bunch and give you an idea how much the brass to clean up

The RCBS 3way does all three steps on one.

 

[Campbell]

Many thanks for this chaps!

 

[amlevin]

Just a tip I got from an oldtimer (real old), the more you chamfer the outside of the neck the more chance of soot making it's way between neck and chamber. Just chamfer enough on the outside to remove any burr you can feel when you run a fingernail from shoulder to case mouth. If it doesn't hang on a burr, you've gone far enough. If you can see a chamfer, too far.