Kirby,
As you probably already know, there'sa list of things to check when a rifle acts erratic. Bedding, scope, scope bases if applicable. Sometimes a front screw will be long enough to bottom against the barrel shank. Then sometimes the front guard screw will be too long, and bottom against the barrel shank. Firing pin draggin on trigger sear because stop is set too close is another reason, and causes firing pin drag, and inconsistent ignition.
Sometimes it takes a while to find the problem, and unfortunately sometimes you never do.
A good friend of mine has one of the .17 MKII's and it shoots pretty well at 50 yards. I'd say in the .3-.4 range. It's a 1710 HB Anschutz. Nothing like our match rifles in .22LR but plenty adequate for what it was designed for.
Good luck with yours, and let me know what you might find out to cure it. It's always interesting to see how some of these little problems work out.