Be aware of two industry standards for AR in 7.62x39 and other large bore variants.
The AR industry has reached the level of the 1911 pistol customization industry. Various 1911 parts manufacturers offer improvements to the original design with different dovetail sight cuts, ramped barrels, etc etc. If the amateur isn't sharp, he/she might buy parts that are not dimensionally compatible. The same thing is happening in the AR industry.
The AR industry now has two headspace dimension standards for the 7.62x39 cartridge, and they are not mutually compatible.
'Type 1' is industry standard for most 7.62x39 rifles (Colt's original spec). Some 264 Les Baer and other cartridge developers cut chamber headspace to that same spec. Some wildcats use 7.62x39 as the parent cartridge and keep that same spec. Type 1 boltface depth is 0.125".
'Type 2' is the way Alexander arms began cutting their 7.62x39 bolts several years ago, .010" deeper than Type 1 Colt spec: 0.135-0.136" (depth of bolt face). Other cartridge developers followed.
To the best of my knowledge, Model 1 Sales follows the Type 1 standard. Black Hole barrels made before May 2011 use the Type 1, but changed after that date. Those are the only two I know for sure, if in doubt you better ask who made your barrel. Or buy bolt and barrel from the same manufacturer and verify compatibility at time of order.
