There used to be a really good metalsmith on here named 30cal that builds M1919 Brownings. I haven't seen him in some time but he's a really good reasource.
I cant offer you any experience with an impact hammer. Pressing I can, hammer I cant. Definitely interested in the build. It's one I have given some thought to. I am almost finished with my post sample M1919 and have been eyeing a couple M2HB kits.
There used to be a really good metalsmith on here named 30cal that builds M1919 Brownings. I haven't seen him in some time but he's a really good reasource.
Appreciate the offer praff, might take you up on that if the hammer doesn't workout. I'll most likely buy some spare rivets to practice with first before I hit the receiver.
Check out 1919a4.com 30calmachine gunner is more active over their. And there is a lot of build info on that site. Good guys too! One of the guys over their sells a mostly universal rivet jig/tool.