Short-stroking with 90gr TNT, fixed with gas port work

[Harpoon1]

Could be, I don’t see any obvious exhaust leaks, other than possibly around the gas key/gas tube connection. That’s a good thought though, I’ll swap BCG and see if that makes any difference.

American Eagle claims 3000 fps with the TNT, suppose that with a 24” barrel. Using 25-30 fps per inch, that still leaves me considerably on the low side. IIRC DNS was getting 2800+ fps out of his 18” AR’s with TNT’s. Maybe I just have a tight chamber and slow barrel?