OFFSHORE: I understand about Mother Nature. Yesterday the wind was the usually 16-18 MPH and I was trying to shoot pistols at my usual 50-100 yds. Even with 225-250 gr bullets they get pushed around and move sometimes 6-8" at 100yds.Especially when it gusts.
I did find the N120 and might point put that it really shines in cases like the 221 Fireball, and a few others where you have a small case and higher pressures. (think bottleneck)
When it comes to Pdog hunting it is my first choice for the smaller stuff. Clean and gives good accuracy.
As far as the N120 and it's use in the 45 Colt cartridge. Well that is up to you but,, you might as well know right now that you will not burn but about half of the powder and the velocity is certainly going to be in the lower range. I think there are better choices out there.

280,300,310, 315, 325,335, different grain cast. I have tried a lot of bullets. Hodgdon, H110 is hard to beat. Especially with the heavier bullets.
It gives me the velocities that I like or want.

That 280 gr cast opens up several possibilities as far as powders. H4227 was one that worked well with that weight. For an even milder load W231 was good.

I am going to ask what is the intended target with this combo?