Ok, I'm looking into the possibility of building a HK91 type gun at some point, using a pre-welded US reciever... I like the 91 design, simply because it's one of 2 .308 'battle-rifle' types that doesn't use a gas piston system (the other being the oh-so-expensive AR-10 of course)...

Apart from the trunions, is there any other welding needed to turn 'parts kit' into 'gun'?

Does building one of these require special tools?

Or am I looking at a 'too difficult to bother' project?