Huldra arms 5.45x39

[cstone]

How did the lower break that hammer? I don't know ar's that well or did I read it wrong?

I believe these are plastic hammers and triggers. The hard primer on surplus 5.45 requires a stiff spring and this puts extra stress on the hammer.

I am building out a CavArms lower for a 5.45 upper and plan on using a Rock River lower parts kit. I hope this will help me avert the problem here.