A dremmel is your friend. I did that mod long ago. It's s manual hold open, not a bolt catch. Very handy when you need iti believe Yugoslavia used the magazines that had followers that caught the bolt. What I rather do is get a selector switch that has a hold open notch cut into it.
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Serbian type mag and normal mag
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It is important for when one would like to keep the bolt locked open during cold range.A dremmel is your friend. I did that mod long ago. It's s manual hold open, not a bolt catch. Very handy when you need it
I'll have to get me one of theseMAG47 MIL - 30rd AK47 Magazine GEN 2 - XTech Tactical
www.xtechtactical.com
These are good mags and you can add the BHO if you want. The only reason is to show you are out before pulling the trigger but really not that big of a deal imo.