I have a couple New Model Single-sixes and noticed the difference in the thread diameter upon removal of the barrels. Any idea? The newer one has the larger diameter. Was curious if all the stainless barrels were the larger version?
I found out the same way. I had two barrel changes on the same day, and neither would work! I checked every 22 and 32 single six I have.
Blue or stainless made no difference:
OM and pre 1986 NM Single Six .22 barrels, and 1st year, 1984, thru part of 1985 .32 barrels are 20 tpi x .557”, the shank at forcing cone is .430” (earliest .32 I have with this thread is # 650-01300, 1st year, 1984 and the latest is 650-06801, from 1985 with this thread size).
Post 1985 .22 barrels are 24 tpi x .622”, with the old size shank of .430” (lowest I have is #261-18748 from 1986) and .32 barrels are also 24 tpi x .622”, but with a shank of .486” (lowest I have is # 650-14117 from late 1985).
All the 32 Vaqueritos will have the larger thread.