Problems at the range today

[Dirty Mike]

today we took 3 guns out to the range, two Big Horns and one black diamond we shot 3 different rounds, one hornady sst 50 cal 300 grn , dead center 300 grn and a hornady 350 fPB , we were also using 777 loose and 777 pellets, we were shooting the fpb out of the thompson with pellets and noticed after each shot it kept walking 2.5 inches per shot up the page, i was shooting the sst's out of my big horn and getting greats groups everytime, i was using loose powder, so my buddy went to try the sst out of both his guns, after two shots from his big horn we noticed that the kick wasnt there after each shot, we walked down to the targets and noticed that the bullets wernt shooting straight that were tumbling out the barrel and hiting the target sideways we pulled a bullet out of a stump and it actually went in backwards, also we had firing problems 6 caps without going off, the bullet shot great with loose and standard pellets anybody know what would cause the tumbling? and has anybody had firing problems with Triple 7 pellets?

[CP]

Keyholing is usually caused  by the bullet not engaging the rifling properly so it comes out of the barrel with little or no spin.  The result is a wobbly bullet much like a football thrown by a third string quarterback.

My guess is that the pellets didn’t burn fast enough to accelerate the bullet enough to cause it to shorten and expand and engage the rifling.  Obturation is the word.  You are not getting enough acceleration to properly obturate the bullet.

[Dirty Mike]

Makes alot of sence thank you