Hello, This one is really strange... around 1972 or so, I was out squirrel hunting with .22. Now this was no ordinary .22, it was a mod. 81 Marlin bolt gun, which I had converted to needlefire...Don't ask. Anyway, it used std. L.R. case with tiny hole drilled thru center of head. Long drill-rod firing pin.
Primer was blue-tip strike anywhere match head backed up with case full of Unique, & sandwiched between base of cast-bullet I had made mould for.
It usually went off when trigger was pulled, except in very cold weather when you might get a hang fire. Squirrel up in tree about 30yd away, couldn't see head too well, so aimed at neck. At the shot, squirrel just sat there unmoving. Thinking I missed, I reloaded & putting sights on him again, I watched as he slowly fell off limb..but stiff looking. I picked him up, but couldn,t find a mark on him...only a very slight disturbance in fur at back of neck, but skin was not touched in any way. I've heard of "barking" but there was no bark! His head could have been in such a position to bring spine up tight against hide, but again no real mark?