I have reloaded the .45 Colt and .45acp for 40 years.
In a nutshell...here were the (most obvious) problems:
1. .45 Colt chambers in Rugers were inconsistent....some were .450, .451 and some even .453....the results were predictable....inaccuracy!!!!!
2. .45 Colt chambers in older Colts were equally unpredictable...some .455 or .456.
3. Freedom arms were perfect at .452....very accurate...
all of the above.....same load!!!!
I had the Rugers, with small chambers rechambered....the guns were accurate. The Colts, not so much....had to cast and size bullets to fit the gun, and THEN, accuracy improved...
None matched the Freedom Arms...
My S&W, Model 25 in .45 Colt is a tack driver...(Heritage series)
I use a Keith Style bullet, with Accurate Arms #5 for mid-range loads @ 800fps....terrific..Powder meters beautifully.
My Smith Model 625 is one of the most accurate .45acp firearms I have owned...accuracy is comparable with my 945 and Les Baer bullseye gun.
As a side-note....
my earliest Ruger .44 Mag Super Blackhawk had little accuracy...I finally had the barrel slugged, and low-and-behold the barrel was .434...when I cast an appropriate bullet, 429244, (one that would size at .434), and used the proper sizing die for the gas-checked bullet, the accuracy was what we call one-hole....
check every aspect of the gun...cylinder and barrel slug....match to bullet and all will be fine.