Howdy
Some cartridges in my collection.
First, a whole slew of 45 Colts of various ages. Modern round on the left. Yes, all the old rounds, except the one on the far right had tiny rims, not suitable for a rifle extractor. The round all the way on the right was for the Model 1909 Colt and had a large rim for the extractor of the revolver.
Frankford Arsenal Benet primed 45 Colts. No they are not rim fire, they are internally primed. The dents near the bottom hold the internal priming in place. These are copper cased, folded rim rounds and a rifle extractor would have ripped right through them.
It ain't the 'extractor groove' that makes a round suitable for a rifle. Notice the 44-40 and 38-40 at the right in this photo. Guess what? No 'extractor groove'. The 44-40 and 38-40 were designed specifically as rifle rounds, and had larger rims for the rifle extractor to get a grip on. No 'extractor groove' was necessary. The 44 Mag and 44 Special on the left have grooves that are artifacts of the machining processes used to make the brass. They are not really 'extractor grooves', although they will help with extraction in a rifle. No extractor groove on the 44 Russian in the middle, but it is a revolver round anyway.
P.S. The cylinders of the old Colts were the same diameter as the cylinders of a modern Colt. Modern 45 Colt ammo has a rim diameter of .512, plenty for a rifle extractor to grab. The rims on most of those old 45s in my photo are running around .505, not enough for an extractor to grab. And modern 45 Colt ammo will chamber just fine in a 1st Gen Colt. The old rounds had tiny rims because there was no need for a large rim. The Single Action Army (the gun the round was designed for) had an ejector rod that poked the empties out from the inside. No need for a large rim for an extractor, it just was not even considered. All the rim had to do was prevent the round from being shoved forward by the firing pin, you don't need much rim for that.
Regarding the business about 45
Long Colt, when the Schofield round was developed in 1875 it's military designation was Revolver Ball Cartridge, Caliber .45 M1875. It was not refered to as the 'Schofield' cartridge until years later. There may well have been some 45s labeled 45 Long Colt, but I have never seen any. You can see the military designation of the 45 Colt right on my antique box of ammo. According to Kuhnhausen, the 45 Colt 'was not referred to as the
45 Long Colt until some time after the short M1896 ordinance and commercial cartridges were introduced.' The M1896 round had a OAL of 1.42, whereas the earlier M1875 round had an OAL of 1.438.
Regarding mixups of the wrong cartridges showing up for the wrong revolvers, modern gunwriters like to speculate about that, but there are no documented cases of it happening. We can talk about why S&W developed the shorter round another time.
Today, the name 45
Long Colt seems to be pretty much of a modern phenomenon, started by clerks in gun shops. You walk up to the counter and ask for a box of 45 Colt, the clerk says 'You mean 45
Long Colt? He just wants to make sure you don't want a box of 45 ACP. I have heard this exchange many times. He has probably never heard of the 45 Schofield round.
Finally, regarding soot on the case of a 45 in a rifle, with low powered loads you are going to get soot on the outside of the case. Period. You do not develop enough pressure with a low powered load to fully expand the case to seal the chamber, so you get blow by. Increase pressure and the soot will go away. But frankly, a little bit of soot on the case means nothing. It certainly is not going to affect the performance of the rifle. I have been seeing soot on 45s for many years now in CAS. If you want clean shiny brass, up the pressure. If you want light loads, don't worry about a little bit of soot.