It does sound a little loose but there are a bunch of things to consider.

The pellet will obdurate when the gun fires to fill the bore. However if the breach leade has a sharp edge it will shear off the widest part of the skirt which can compound the problems with a loose pellet.

The Cardew's said the ideal springer breach has an edge which is just barely rounded. And a fired pellet will show clear deep rifling marks in the skirt and just barely discernible marks on the head. Fire a pellet into a bucket of water to check this.

Also there has been a lot of study into that crimped dovetail found on the German guns. The common held theory is that it functions as an effective choke.