AR9 Virgin Assembly Ka-Boom

[Walkalong]

Spacers are to save wear/breakage of bolt catches.

Looks like a classic case of bullet setback and the resulting over pressure.

 

[bfoosh006]

Bolt Bounce... and firing while loose of the chamber.. or Out of Battery discharge.
Install a 308ish recoil spring.. if you look at the JP 308 carbine recoil spring, you'll see JP even recommends it.

And double check the crimp on those rounds in the picture.. they look a little wide.
And if the crimp is loose, the setback will be easier to happen.... and full insertion into the chamber may not happen.

Also polish your feed ramps, the bullet setback is from the rough feed ramps "grabbing" the bullet , rather then it sliding on the feed ramps.

I run a Tubbs .308 Flatwire , a 7.5oz extended 9x19 "Dead Blow" ( moving weights ) buffer... and keep the chamber clean ( Important !! )

 

[H&R Glock]

My gunsmith says he's gonna' have my 9mm upper working in a few days.Some fitting required as well as a heavier buffer. I've taken it to a professional.

 

[WestKentucky]

I don’t trust blowback. The physics and mechanics of it make sense, but I just can’t get past it being a spring that’s holding the case in place. Stories like this are far too common in blowback firearms. In a 22 I get it and I deal with it, but that’s low pressure 22 rimfire where high pressure pistol rounds are an entirely different animal.

 

[H&R Glock]

WestKentucky,..... I'll wear two pairs of safety glasses, a steel belted jock strap, and welding gloves when I next shoot it. My GS will shoot it before I do. Wish me luck!