Gomann Berlin

[sheepherder]

Originally Posted by kurusu

Maybe because the 4mm M20 (the one on the left) as no rim and might get stuck after fire.

Attachment 44070

Mario, is the 4mm barrel insert rifled or smoothbore??? Primer-only ignition can't be all that powerful, even for a .157" projectile...

A barrel insert installed from the muzzle leaves the chamber end unsupported...The Luger chamber is ~.386" dia and the bore is ~.346" dia...So the barrel insert is unsupported at the chamber end by ~.040" total...(.020" radially)...So you can't have too much chamber pressure or it would expand the insert, making it 'difficult' to remove...