It amazed me how the thickness of the cases varied, thus, your taper crimp would vary. A barstow match barrel gave me fits till an old timer gave me some hints on setting a taper crimp die for a particular neck thickness(brand)....problem solved.
One of the benefits/curses of not sleeping at night is you have all kinds of time to squander on "I wonder if's". I actually did measure wall thickness' one night to check uniformity. IMI, TZZ, WCC Match, Win, Fed, S&B, PMC, Starline, Blazer. 3 measurements on each piece of brass.
Brands vary considerably in both uniformity and thickness. Best in uniformity was Federal, .0002- .0003, followed by IMI, .0003. Worst was PMC, .002
Keep in mind this is not a blanket statement of a brands QC. It is based only on the dozen or so of each brand I happened to pull from my supply to satisfy my own curiosity.
Experimentation with amount of taper crimp with the different brass will also give huge differences in group size. I used to crimp religiously to .468 with lead and .470 with jacketed. Swaged bullets are now crimped to .462 (Rem & TZZ Match brass), cast to .465 (WCC 90 Match), and jacketed (50 yard stuff) to .469 (TZZ Match and Rem). I use cast or swaged lead at 25 yards & under. Jacketed 185 hp at 50 yards.
All loads are run through my Ransom Rest at an indoor 50 meter range, so there is some consistency . The RR WILL NOT give you the best the load CAN shoot. The trained human hand will normally give the best. However the RR is consistent from the first load tested to the 20th load tested. The human hand & eye aren't.
The 3.8- 4.2gr of Bullseye load with either a 185 or 200 lead bullet is an excellent mild, accurate and forgiving load. Some 1911's will need to have a lighter recoil spring, but not all. If it's going to be a hunting load the above loads do not deliver sufficient energy for anything but small game.
As was mentioned. Your barrel is the best case checking instrument. If you're loading for several 45's, determine the tightest chamber and use that barrel. Remove it from the slide & chamber each round in the barrel. Anything that goes in tight, recheck the crimp or put it into the practice can.
OAL will vary with different bullet styles within the same grain weight if you measure cartridge base to bullet shoulder. Some bullet noses are quite long & will give you functioning issues because they wedge against the inside of the magazine. Usually on shot # 2 or 3. I seat everything (except jacketed) so there's about a thumbnail thickness of of lead exposed above the end of the brass. It works for every bullet I've tried so far.
Several have mentioned that the 45 is not a difficult cartridge to load for, and they're right. You can make this as easy or difficult as you want.
Enjoy.
Al