Has anyone hunted deer/bear/pig with a fixed sight 45 Colt Vaquero? Were the sights difficult to use for that situation?

The one I have, I had a Bisley frame fitted to and had the smith open up the notch in the rear so its more squared in shape and filled the front sight to dead on with my one load, have used it for hogs and one deer

USN
DAVE'S plan is a good one. I would test the loads I thought would be suitable, pick the one I liked the best and "adjust" the fixed sights to the point of aim, point of impact I desired.
Do not forget to try some Speer shot shells for your 45 Colt. I hsve used them for snakes and a lot of small game for the pot in a 1911 45ACP and a 44 Mag.

I did as Dave has done but started with a 5 1/2" Bisley Vaquero. I had Bowen open up the tight throats. I fitted a Belt Mountain pin and I worked the trigger to a pretty crisp 4#. I use one load in it utilizing the 325 LBT LFN over H110 and filed and serrated the sight dead on at 50 yards. It makes for an nice light, accurate, powerful tool.