Alright, here you go.
Here is my 10 round group at 10yds with my .22 Sig Sauer Mosquito:
Here is my 7 round group with my Springfield Champion .45ACP at 10yds:
...This was my first run through after 100rnds through the .22 and the 2 low are my overcompensation for the change in recoil when I switched to the .45.
Just get more comfortable with the Sig. The trigger or sights or something are a little different than the 1911. It's probably something a more experienced shooter would recognize and overcome pretty quickly. There's nothing wrong with the gun. Just get some more range time and you'll be good.
Edit: Just saw your comments about the two low shots with the .45 group. To me, that says more than anything else about your shooting. There should be no "overcompensation" for the change in recoil. That's your problem, right there. You're anticipating recoil and jerking.
Firm grip. Slow steady trigger pull. The exact instant the pistol fires should be a bit of a surprise.
GJ, are you left-handed?
edit: nevermind, I see you posted right as your main grip, however I still concur with Devil's analysis, above - surprise trigger break is the key.
(1) dry fire drills - squeeze the trigger as slowly as possible to learn where the break is. As you squeeze the trigger, visualize it as the sharp end of a tack, if you squeeze too hard or too fast, you'll break your skin. Also, if you can, balance an empty casing on your front sight while you do this. If the casing falls off, you didn't do it right.
(2) quit using the .45 for a while, concentrate on the .22 Again, no recoil, no anticipation. Once you can shoot tight groups with the .22, it should be easy to move over to the .45
What is the real danger, if any, of actually damaging the firing pin by dry-fire drills? I have heard the whole spectrum of opinions from various people. From,
"Dry fire drills without snap caps will DESTROY YOUR GUN!!!"
"Snap Caps? pfffft....Dry Firing is GOOD FOR THE GUN!!!"
With your 1911, I would absolutely recommend snap caps. The operator is a fine pistol, no reason to even risk damaging it.
Again, my 2c. I have only rarely dry fired my weapon sans snap caps.
It's perfectly fine to dry fire a 1911 without snap caps. In fact, if you look at a Kimber manual (or at least ones I've seen in the past) it will tell you to pull the trigger during assembly and disassembly.
You're dealing with a hardened steel firing pin. You're not going to hurt it. If you happen to somehow, a new one is 8 bucks from Brownells. If you're feeling like splurging, get a new spring too and make it an even 10 bucks.