.303 Barrel chamber reamed to 7.62x54

[Vincent]

Thought some of you might like to see some pictures of this.

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There is very little material that gets removed. So I decided to do it by hand.

Cleaned the chamber really well, then filled it with cutting foam and coated the reamer. Ream a little, clean out the chips, and repeat. I dropped a round in to show the progress. Just as I neared the end I went very slowly and lightly, removing very fine flakes that looked like dust.

Information

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[Peter Laidler]

I have turned 'a few'; Bren and L4 barrels and they cut very well and easily. Must be good steel but pretty much expendable in service, even with a good deal of care

[Vincent]

It did cut very smoothly and easily. I was impressed by the smoothness. Doing it by hand I could really feel it.

[djandj]

And as the grateful temporary recipient of said barrel, I can attest that it shoots great (so far) Both steel and brass.

[browningautorifle]

Sounded just about right Vince. I've done a "Few" too and by hand is fine, in the lathe with tail stock steering is usually preferred for true...but I like the way you did it. Finished product looked about perfect. Yes Peter, they're made of good material.

[Vincent]

Thanks. I used a piloted finish reamer. There's very little to take off. It would be hard to get out of true.

[browningautorifle]

Hardest reaming job I've done to date was a .22 barrel I wanted to put a 5.56 chamber in so I could use a CMMG kit in it. All assembled onto an AR platform of course. I had to use progressive sized drills to remove enough material to roughly form the 5.56 chamber and then ream with a new finishing reamer. I drilled in the lathe of course but did the chamber by hand. Whole thing worked perfectly...

[Vincent]

Does anyone know what the tolerances are on new Mk2 barrel threads? There must be a range that was considered acceptable, right?

[TactAdv]

Does anyone know what the tolerances are on new Mk2 barrel threads? There must be a range that was considered acceptable, right?

Vince, I believe it is extremely close to a modern-std SAE Class 2 fit. I was told that by a very well informed machinist who had reversed made a few tubes in weird calibers.
-TomH