Re: m40a1 contour
From the build guide:
I don't know if you'd be interested in this for your thread, but I got it during a conversation I had with Gary Schneider of Schneider barrels, back on 8-17-06 @ 3:30PM, via telcon.
I found he was a most pleasant person to talk to and surprisingly gave me information freely, considering he didn't know me from Adam, though I live not too far from his shop.
He said the M40A1 barrel dimensions were 1.10-1.210 +/- X4", straight tapering to .890-.910 +/- @ 26.5".
After cutting and threading the breach end you would end up with 1.20" X3", +/-.
Once it was threaded at the breech end they(the USMC armorers I believe) would trim the muzzle of the barrel to 24" from the front of the trued recoil lug, as is their method of measurement, making the muzzle approximately .920-.940, again +/- . ;\)
He stated there were variations of +/-.015", maybe more at times.
He also said the barrels had a rough turned finish when supplied to the Marines Corps initially as they were rushed to meet the deadline. He said he offered to make them smoother on production models if accepted(which he was), but the Marines liked the rough finish as they said it held paint real well, so he made all the rest of the contract the same way.
I was curious about the 1.20X3" finished breech end measurement as I was not used to that. Most civilian rifle barrels I had used or seen previous, had measurements of 1.25"X 4-5" X whatever length. He said that was strictly to facilitate the use of the night vision equipment they had/have. Any longer or thicker in the breech end would cause interference with the objective, or other parts of the NV equipment. So it wasn't just some outdated military quirk. This was info I hadn't known, and I learned a lot in that conversation.
