Several years ago, I bought a Browing Abolt .270 new, and it did the same thing your talking about. I would dent the primer as you explained, but not enough to "shoot".
Sometimes it would shoot all 20 shells in a box and it may miss fire 10 shells out of the next box. :
I ended up trading mine*(the guy said he would send it back to Browning)
Seems like there was a lot of talk back then about Browning making there firing pens to short???Good luck