The synthetic stock thing applies to standard SKSs that have fixed mags. To use a detachable mag on them, you must use the synthetic stock.  As for the bayonets, even if they come in the box, it is illegal to mount them, whether they are single-bladed or triangular. This applies to SKSs only; it's one of the entrapment snares the ATF put out there to confuse people. The only exception is for C&amp;Rs. You're getting wrapped around the axle of trying to use shortcuts to understand 922(r). You need to stop trying to use the shortcuts and just read 922(r) - once you do, all these thoughts that the material in a stock is somehow special, will vanish rapidly.    In order to have a detachable magazine, you must have no more than 10 imported parts on the rifle. The stock is one of the more commonly replaced foreign parts - and there aren't a lot of WOODEN domestically produced stocks. Most of them are synthetic. That's where this understanding came from.    This site is pretty good on this matter -  Gunwiki: 922(r) Worksheet for SKS Builds    Years ago, you just plain could not get a lot of the compliance parts you can get now. It used to be that you could get US-made gas pistons, stocks, magazines, and not much else. But now you can get fire control group parts too, which opens a lot of other options for 922r compliance.