Barrel thread in receiver

[homebrew .357]

Hi Guys, The plans I have for the Sharps rifle in 45-70 have a square thread, (10 M O D. Square threads), for the barrel and the receiver, I was just wondering if you could use a Whitworth or A N C threads , say 14"/16" . Why ?, It`s just that there`s would be easy to cut than the square ACME threads ?, I think, I have not cut square threads before , , so just asking the PRO guys here before I do anything, not that I can, no barrel or receiver yet, Thanks, Homebrew.357.

[hammermill]

wirhout doing a lot of fun math and chart comparison, I see no reason you can not use any thread you want to as long as everything screws together tight. the blackpowder will not be putting a mass of pressure on things. you will proably be putting most of the thread wear on during assemble and testing. .

[GeorgeGaskill]

The worst thing about square threads is grinding the bit. Once you have that done, the actual threading is not that difficult. Since you have some spare time before you need to cut the threads, why not practice cutting square threads on and in some scrap material.

There is a minor advantage to square threads in that they do not cause expansion of the receiver threads nor compression of the bore when tightened. Since the tightening is in the chamber area, it probably doesn't matter very much. In a revolver barrel, you are causing a tight spot at the forcing cone and then the compressed bullet is not so good a fit down the rest of the bore.

[homebrew .357]

Thanks for the reply`s Guys, Have just got holed of a old charts book on thread tables ,so will have a bit of practise at cutting the acme threads, if it was good for Sharps it should be ok, and it`s all ways good to learn something new. Homebrew.357.

[Harold_V]

It should be noted that an Acme thread is not a square thread.

Harold

[homebrew .357]

You are right Harold, Acme Threads , = 29 degrees and for 10 threads per inch, pitch +0.100", depth of thread = 0.060" . Now I`v got the chart I become a pro, , don`t believe it , . Any way it would appear to be a good strong thread and my only worry was it could come lose after say 10,000 rounds!
will have a check when I get there, Cheers, Homebrew.357.