On a shorty psl build an 1/8" hole was used. Id say put a 2mm hole in it and try it.
I dont see why thats relevant, Hole size is dependant on how much barrel is forward of the gasblock. The less barrel the bigger the hole. If hes building it start small and work up.
http://www.gunco.net/forums/f43/ak-barrel-info-67438/
THAT MIGHT BE TRUE ON A SUPER SHORTY PISTOL BUT ON A RIFLE ITS NOT GOING TO MAKER A HUGE DIFFFERANCE ON AN AK. LIKE I SAID IF HE IS CUTTING DOWN A 22" BARREL TO 16 HE IS STUCK WITH THE ORIGINAL HOLE SIZE TO BEGIN WITH TO BEGIN WITH. TRY IOT AND SEE HOW IT WORKS. IF HE IS MAKING A NEW BARREL OR RELOACTING THE GB THEN GO .020 SMALLER AN WORK BACK UP.I dont see why thats relevant, Hole size is dependant on how much barrel is forward of the gasblock. The less barrel the bigger the hole. If hes building it start small and work up
IMO THINGS ARE GETTING OVER THOUGHT OUT.
ON MY 308 AND OTHER CONVERSIONS I START AT ABOUT .065 AND GO UP FROM THERE UNTILL THE GUN WILL CYCLE ON THE LIGHTEST LOADS I PLAN TO SHOOT.
MANY FACTRY AK,S ARE OVER GASSED SO THEY WORK IN DIRTY COLD CONDITIONS. IT WOULD BE BETTER TO RUN A LITTEL SMALLER PORT THAN STOCK IMO AND ITS WHAT I DO ON MY TARGET STUFF.
I drilled one at .067, it was fine. .064 to .067 would be my advice.