Quote Originally Posted by nurek View Post
I don't have any theoretical evidence, but I think it's self explanatory, higher pressure behind pellet + friction resistance, the soft metal skirt will expand as it's moving (if it has place to expand)?

Do you think otherwise?

I have done a test where I have squashed a pellet skirt and measured the velocity, as expected it was lower, however the skirt 'opened' up. Probably more pronounced in a springer due to higher pressure... I only shoot spring guns.

As you work with barrels, you could do an experiment, where you push a pellet through a barrel (hence 0 pressure on skirt) and see how the skirt is deformed, and fire one, if the markings on the one that has been fired are deeper, the skirt has expanded.
That's exactly what we did . We could see no noticable difference .

It only works with an unchoked barrel of course

I'll try find the pics