Barnard action cone angle?

[Jay Christopherson]

Can someone confirm the angle of the cone for a Barnard Model P? The bolt nose itself seems to be 30º, as best I can measure with the tools I have. The dimensions doc I found seems to show a 20º angle for the chamber face:

http://www.barnard.co.nz/images/Tech%20drawings/barrel%20thread%20drgs/model%20P%20308%20barrel%20thread.pdf

The chamber on the barrel I removed was done at 30.5º (that one I can measure exactly with a little trig and a DTI) and I'm not at all sure it was done to Barnard spec.

 

[clowdis]

Just typing from memory here, but if I remember correctly (according to the Barnard dwg.) the angle for the cone in the barrel doesn't match the angle of the cone on the bolt. They give the 20 degree angle for the barrel cone to create a little bit of extra clearance as you get toward the outside of the cone/bolt clearance. In other words you may have .005 clearance near the center of the cone and .015 clearance towards the outside.

 

[Jay Christopherson]

That's what I was thinking based on the blueprint, which is why I don't think the barrel I took off was done to Barnard spec.

 

[Jay Christopherson]

I checked with Barnard directly and they indicated that the dimensional drawing on their website needed to be updated. The correct angle is 25º. The original 20º would also work, but their recommendation is 25º.

 

[Preacher]

Set your angle at 66 degrees and all will be good...........

 

[clowdis]

OK, ya'll have forced me to go back and pick up my drawings of barrel stubs that I have done for Barnard actions. I measured the cone angle of the bolt at 122 degrees with a protractor. I have my compound rest set at 29 degrees for threading so I just cut the cone without moving my compound. This doesn't give quite as much clearance as the drawing from Barnard shows but as far as I know it has never failed. (Disclaimer here) I have never seen the cone angle of the bolt published anywhere and measuring with a protractor is only good within a couple of degrees at best, so it might be best to go by the manufacturer's drawing and be on the safe side.

 

[prwhite]

I have both “P’s” & “S” actions. The bolt nose is 30deg. The tenon drawings show a 20 deg Breech cone. Do not make the breech cone match the bolt, or you will have some case head exposed when finished.

 

[Alan Warner]

I have both “P’s” & “S” actions. The bolt nose is 30deg. The tenon drawings show a 20 deg Breech cone. Do not make the breech cone match the bolt, or you will have some case head exposed when finished.

Not if you cut a flat aat the bottom with a dia that is .005/.010 larger than the flat face of the bolt nose.

 

[NZ_Fclass]

I have both “P’s” & “S” actions. The bolt nose is 30deg. The tenon drawings show a 20 deg Breech cone. Do not make the breech cone match the bolt, or you will have some case head exposed when finished.

Zombie thread - I guess he has fixed it by now

 

[Cigarcop]

Not if you cut a flat aat the bottom with a dia that is .005/.010 larger than the flat face of the bolt nose.

Yep…. How I cut them

 

[Doug Beach]

25° cone for .308 bolt face, 18° cone for .223. No flat. Feeds great, no excess case protrusion.

 

[prwhite]

Not if you cut a flat aat the bottom with a dia that is .005/.010 larger than the flat face of the bolt nose.

I agree.