I've heard that the .45 do to it's large case does not shoot lite loads well, but since the brass was designed to fire at low pressures it does not last as long with hot loads and as we know with some calibers, when you go outside the velocity norms they sometimes are not as accurate. What is your take?or experience? I imagine if you keep pressure in the 20-25 thousand ball park brass life is pretty good,
First of all, 25K CUP is the SAAMI limit for "Ruger only" loads and it can push the .45 up past the .44 mag in power due to the bigger piston, more area of bullet to push on. Yes, 25K CUP in a .45 Colt can out power the hottest of .44 loads or at least equal them. At these pressures, I have NOT seen any lack of service length for the brass. Of course, my hot loads don't quite match the hottest loads I've seen in the literature or those of Buffalo Bore, so they're probably down around 20K or so CUP is my thinkin'. A 300 grain bullet at 1120 fps from a 4 5/8" barrel will do anything I need doin', though, and it bucks and snorts, too, lets you know it ain't no pop gun .45ACP. As to accuracy, with both my light load (255 grain cast at 950 fps) and my heavy load (300 grain Hornady JHP/XTP at 1120 fps) will shoot 1" or less (rested, iron sights) at 25 yards. That's about as good as I can shoot with irons from a rest, frankly. My TC barrel is actually a .45/.410, not an accurate combination for .45 as it has a ton of free bore to put up with, but with a scope on that barrel, I could keep all shots into 7" at 100 yards. I have no doubt with a proper .45 Colt chamber, that gun would put 'em in typical TC 1-1.5" groups at that range.
I have found the .45 Colt to be one of the easiest calibers to handload for and get accuracy. The big bullets can make up for any casting imperfections just because their mass makes a small bubble less of a percentage of the overall mass of the bullet. A smaller bullet with the same imperfection will show more effect on accuracy. Add to that the fact that larger bullets tend to cast better in the first place because they don't tend to lose heat as quick in the casting process. Bullets out of my 255 grain mold come out lookin' like factory, very few culls, right from the start. That really ain't the case with .38 caliber. I don't cast .44 so can't comment on .429".
The cowboy shooters, for light loads, are using trailboss now. Trailboss is designed just for cases like .45 colt, bulky powder, but fast burn. It takes up most of the case, yet produces light velocities. I have not had a problem loading unique behind my 255 grain cast bullet, though. I get 950 fps which might not qualify as "light" to a .38 special oriented shooter, but it's a cream puff load recoil wise, yet still packs something under 500 ft lbs energy. One thing I like about that load is that if I'm out hiking, I can load with it for small game and still have a strong load for defense against bigger animals and possible 2 legged pot growers or something. The round can be loaded lighter than this, though, with Trailboss, and produce target grade accuracy. This is the whole reason for Trailboss, 10,000 CAS shooters can't be wrong.