Wait, wait, wait. The G3/91 stock is not interchangible with the 93! The 93 and 94 stocks are interchangable. Please don't go cutting down a stock and trying to make it fit. If you're looking for a an A2 stock you can pick up an MP5 A2 stock for about 50.00 dollars and slap in on your 93.
The A3 stocks are even less alike. And Vector's 93 A3 stocks are not cut down versions of the 91 stocks! Go look at a 91A3 stock, it has a recoil rod attached to it and a two hole end cap for a reason.
The foot of the old 93/53 stocks are similar to the 91, but they're not the same stock.
I'm sorry, but information like this is dangerous and could really get someone hurt. I'm all for cutting down forearms and removing sights, but the buttstock on this G3 model gun contains the buffer and the recoil rod! It's bomb waiting to go off that'll shove a steel rod through your head. I'd leave that alone.
My .02!
Regards,
R.