Bill: I haven't fired mine that much and the only handload I ever ran through it was 47.0 H4831sc with a 140 Hornady, something I had been using in a bolt rifle. That is, a near max charge of fairly slow powder. Worked just fine. We are cautioned to avoid the slow powders in gas guns with op rods but, of course, the Ljungman has none. I honestly don't know how sensitive it is to port pressure but perhaps a load which is strong enough to operate the action and not so strong that it bangs the bolt too hard will be ok. Maybe someone more knowledgeable will contribute.
