Free bore

A

ArtinNC

New member
What Dia should the free bore of a 6mm be ? how much larger than the bullet ? If so by how much ?
Thanks for your comments .
 
For short range BR

I like .2438 lots of reamers ground for .2435 however. Main thing is having the freebore bigger than the bullet by a few tenths or so.

Richard
 
The main thing is to have a freebore diameter larger than the groove diameter of the barrel.
.0005" doesn't always get you there.
 
Dave Tooley said:
The main thing is to have a freebore diameter larger than the groove diameter of the barrel.
.0005" doesn't always get you there.
Click to expand...

Roger this, Dave! I just finished a barrel for a pal - first barrel I've done on which the 'free-bore' portion, of a proven reamer (.2046" free-bore Dia.), never touched the groove(s) . . . I reckon, by the Hawkeye view, it's a ZERO free-bore, 1.5 Deg. "throat" !??!;):confused: It's not a BR type of [button-rifled] barrel, but of good repute, I was/am surprised at the large groove diameter, while the bore was 'normal' - it's 20 Cal. Seeing how it performs is going to be interesting - I'm betting on up to the standard of < .5MOA . . . I hope - its just for prairie dogs and coyotes!:p:confused: RG
 
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My mics I feel are pretty good and on my reamer I'm getting a read of .2436 . What do you think ? I know all mics are not the same even if they check right on the gauge . My barrel had .237 stamped on the end of it and I don't have a way to check it .
 
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take the drop from the muzzle

ArtinNC said:
My mics I feel are pretty good and on my reamer I'm getting a read of .2436 . What do you think ? I know all mics are not the same even if they check right on the gauge . My barrel had .237 stamped on the end of it and I don't have a way to check it .
Click to expand...

end of the bbl and true the OD, make sure your not in the lapping bell portion Run the reamer in to just cut the freebore-throat. You can see from that everything you need to know without measuring tools.

Richard
 
I had to cut the free bore longer , my chamber reamer was a 6mmBR with a .080 free bore for 65 gr bullets and I needed a .115 free bore for now for 105 gr bullets , and I may have to open it to more . And the .2436 dia I wish was bigger but that means another reamer , I'll have to see how it shoots first .

Thanks for the comments .
 
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