Originally Posted by Mossy Man
When holding it and dry-firing, it seems to feel OK with my thumb over, but the rear of the receiver/buffer tube castle nut bites into my web a little bit.
It sounds like you may be using what we call the "choke hold." A more relaxed wooden-rifle style hold would be more comfortable, and is the recommended hold for most shooters, especially those with larger hands. Be sure to check out our handling link
for photos and descriptions of the two types of hold.
Recommended relaxed hold -- note web of the trigger hand does not contact the rear of the receiver