Quote Originally Posted by Frank S View Post
For the past year now, I have been putting together a selection of 20TPI 28TPI 32, 36 and 40 TPI taps and dies for my work in hydraulics, I have done a few barrels for a couple of friends who do competition shooting, even though I prefer to single point thread a barrel I like to make the final few thousandths with a die. Many barrels are too thin at the end to accept a very coarse thread not that I would ever recommend a coarse thread on a barrel for any reason. To me coarse on the end of a gun barrel means any thread of 20TPI of fewer, 28 TPI seems to be an accepted thread pitch by a few smiths I have talked to but if someone desires to have a modified or full choke added to their 12,16,20, 28, or .410 ga shot gun most of those barrels are way too thin for 28 TPI but 32 or even 40 TPI in some cases will leave 75% of the barrel thickness. The threads must be proportionately longer but the trueness to the center bore is amazingly easier to maintain.
I always wonder why with rifle barrels they don't recess the crown, with my PH bull barrelled target rifle it was the best way to protect the crown, would that help the situation with threading I wonder?