I hope you have gone up on the weight of the recoil spring, otherwise you could be battering the gun pretty well. I would also think that you would want a much slower powder, say Power Pistol to Longshot.
If I wanted to shoot at 200m with a 1911, I would use a 10mm Auto.
Have fun and stay safe.
I've tried other powders. Bullseye wins for the 45ACP. It's the only cartridge I run Bullseye in. Keep in mind that the point is to get the pressure high enough to seal the case as early as possible. I don't do stuff to my guns or my loads without having a good reason, I promise. I was a chemist and metallurgist in a previous life. I have fun and stay safe. I even prove the thumb safety on my target guns. Sometimes you get tempted to just click on and set the gun down, and it's nice to KNOW that it wont follow.
I am using a 21lb mainspring and 18lb recoil spring in both guns. I tried every combination of spring until I found the combo that produced the smoothest recoil and 110% function with the 5.0 BE 200 SWC load. The Springer has about 6000 rounds through it and looks new inside and outside, and the Colt has about 2000 rounds through it and except for some slight bluing wear at the front barrel lockup surfaces, it's perfect. I think that shok-bufs are a lifesaver for folks that want to keep their 1911's tight. I worked all the battering points out of both guns during the first 1000 rounds.
As pretty as the Colt is, if I were going to build a third gun, I'd start with a Springer SS Loaded Target. Frankly, the Colt was not finished well internally and required a lot of very stressful filing and stoning (Damn that Royal Blue) to make it run true. You can't see it, but the grip and safety tangs have been massaged to get the grip on the Springer (which started life as a Mil-Spec) high and tight.
The Colt GCNM has a (factory - It's one of the GCNM design tweaks) subtly reshaped trigger guard to get the grip as high as possible.
I agree about the 10mm - Though I might go for 460 Rowland if it's for real. As I mentioned, I think 44 is really the way to go for longrange handgunning - You can't miss seeing where the bullet lands! I *once* got a tight group on the 150m turkey with a 44. Didn't know it until I wandered out to see if I hit it.
You can turn a cheap Ruger SBH into a longrange target pistol with a half day of filing and stoning and by replacing the sight notch with the 0.090 notch for the Ruger long barrelled models.
I got ejected from the local *rifle* range for having the balls to belly up to the line with a pistol. The RO had a fit. Guess I'll never get the chance to try to pull an Elmer Keith.