View Full Version : Re-threading a HK 91 to US 'standard' thread ???

May 15, 2001, 10:49 AM
What is the minimum diameter threading to go for a rifle muzzle when rethreading. I wanted to go to 1/2 x 28 tpi, but was told it doesn't leave enough meat around the .308 bore. Any help ?? Anyone have experience in this area ? Have seen some gun makers go this small on a .308 but usually only find it on a .223

kurt IA.
May 17, 2001, 09:17 AM
I would say that it,s too thin. Lets do some math. .498 This is normal size for a .5 thread, depth of thread 28 TPI, .866/28= .030 So .498-.060 ( .030*2 because it,s per side) = .438-.308= .130/2=.065. .065 or about 1/16 of an inch is all the meat you will have. You decide. Do you realy want 55,000 psi contained by only 1/16 of a inch of steel?

May 17, 2001, 10:00 AM
thats why i asked the question. Have already been yelled at for even thinking of changing the HK. Don't worry, I won't do it. Thanks