New to me Mk I

[Bullseye]

Not necessarily. The bullet's path could be erratic as it exits the crown but not getting deflected off of the axis of travel and causing keyholes, that is a very extreme wobble.

R,
Bullseye

[greener]

Can you post a picture or two of your groups.

[mark II]

Sorry can't post pics now. I can tell you that I went last night and shot some groups and two came in under a dime and that's what I was looking for. I had one that had a 1 1/2 in. vertical string to it so that was me. I had another that had seven shots touching and the other three 1/2 in. out around the group. My thinking know is with a reddot I won't get a true reading. Even with the dot turned down to one. I am going to borrow a scope and put that on my pistol for testing, on of these days.
On a side note I tried some CCI Green Tag last night and that didn't do any better than the S/V which is good because I have heard S/V going for $60.00 a brick so Green Tag would be double that now.

[Bullseye]

What you may be experiencing right now is a slight parallax error in the dot scope. The best way to examine the barrel grouping is in a Randsom Rest.

R,
Bullseye

[mark II]

I was rereading this topic and was reminded about the headspacing. Last time I measured the headspacing it measured .053". Any thoughts on this? Would turning it down help group size? I get a FTF once in awhile but can't say the reason is the headspacing.
Thanks

[Bullseye]

With the many variations of .22 rimfire ammunition, all you might find if you turned down the headspacing is ammunition that will not operate properly in your pistol. I've looked at case rim thickness over a wide range of brands and there's quite a lot of deviation between brands and even within the same manufacture/lot of ammo. Unless you're making a conscious decision to only shoot high-dollar ammo with tighter production tolerances in your Mark I, then I'd leave it alone.

R,
Bullseye