Originally Posted by
Bagheera
Looking at the amount of air that would be pushed out of the barrel before the bullet arrives:
............barrel .........suppressor
d (mm)...7....... ......32
r..............3.5 .......... 16
r sq 12.3 256.0
pi 3.1 3.1
area 38.5 804.2
length.....600............100 (not counting the overbarrel part )
vol (ml) 23.1..........80.4
The volume of air from the bore is about 23 mL and the suppressor is about 80 mL so the most overpressure I'd expect is about 1/4 atmosphere. The suppressor is designed to absorb and retain extra gas too.
My hypothesis was that the tape could be partly pushed away, maybe still floating in the air in front of the muzzle and the bullet would cut it like say striking a small leaf in the way.
I should have looked for the 5 bits of blown off tape in front of the firing point but didn't think of it at the time. Perhaps they were incinerated by the muzzle blast !
We have to be a bit careful using logic stacked onto our imperfect understanding of the world to predict stuff. In this case, fortunately, it wasn't too hard to test n=5 shots. Perhaps if we tried 100 shots we might find a few that were affected. It would be interesting to see results of other peoples' tests.