.303 Barrel chamber reamed to 7.62x54

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

Attachment 63183Attachment 63184Attachment 63185Attachment 63186Attachment 63187Attachment 63188Attachment 63189Attachment 63190Attachment 63191

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.

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

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

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

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.

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

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...

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

Quote:

---

Originally Posted by Vincent

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