Drill one side halfway, flip it over and drill the other side. That should keep it from egging the hole.Originally Posted by brethankesDiscarding the old piston and makeing a new one is the way to do it. YOu really don't "shorten" a piston, although you could if you were handy with a lathe and didn't mind the extra work. Making a new piston counts as a US part...I am wanting to re-barrel a Yugo for .308 and build a couple really short barrel (about 7.5") Romy kits with the forend retainer in front of the front sight post.
What is the most common method for shortening the gas piston?Most people haven't reported problems with different gas port sizes. The AK design, unlike a FAL, is "overpowered" and basically sends WAY too much gas into the gas system, so a normal size port should be fine no matter the length. You could PROBABLY see a bit of difference if you used a smaller port size, meaning a more smoother action, but possibly at the expense of reliable cycling. No one has really messed around with it THAT much...What method to determine the gas port size for 18" .308 and 7.5" 7.62X39?
The normal 7.62x39 size is that of 11/32" (#16 drill bit).This would work for a Yugo since it has a gas shut-off. You would basically make it a variable-adjustment gas block instead of "on/off". Way back when, around '99 or so, someone actually theaded the block, and used gas jets from an auto carbuerator to vary the action. Personally, I would consider adjustment of the gas bleed like a FAL - more holes = more bleed. That would require some machine work to put on a FAL-style collar, but it could be done. A few crazy people around here have even used a FAL gas block!I was thinking of making gas port adjustable by installing a set screw in the gas block.