Rethreading a prime lr-300 receiver
 

Hey guys, I made a quick purchase the other day and I've hit a bit of a snag- I found a prime lr-300 upper that i bought to put onto my a&k- it fits onto the lower perfectly, but the threading for the handguard is different. After looking around a bit, it's become apparent that prime receivers are threaded to real steel. I will either need to rethread the upper or the barrel nut, or find a prime LR barrel nut, which doesn't seem like a good use of my time. I recall that there was a tool that could alter the threads of your upper, I believe that G&G made it? I can't seem to find it now though.

What type of threads are a&k uppers? I hear the term "airsoft metric" a lot and I'm pretty sure that's what they are. Any ideas/recommendations on what to do?

EDIT: Just found the tool, it was a madbull- Has anyone used one of these? http://www.evike.com/products/28579/

Madbull makes the rethreading tool.
http://www.herooutdoors.com/madbull-...tion-standard/

There's also a Professional version that's much harder (and more brittle) but cuts much better if you're good with it.
http://www.herooutdoors.com/madbull-...ification-pro/