This thread contains some misinformation. I don't want to come on as a "know it all", but good information helps us all:
1 - The original 1917 revolvers, both Colt and S&W carried six lands and grooves. They were made for military jacketed ammunition. They have been critisized over the years as being less than perfect with cast bullets. However, I have had little problem with accuracy in them when the bullets are sized to the throats and made of my "standard" cast bullet alloy (WW's +2% tin). I have used linotype in the "old days" but, frankly, I have NO accuracy problems in my 625's using my standard alloy. The reason given for the six groove shallow rifling was to minimize the hard jacketed military ammo from sticking in the barrel. I have seen xray pictures of barrels with a half dozen bullets stuck in the barrels and the barrel bulged and needing replacement. At any rate, ALL .45 ACP revolvers by Smith, as far as I know, have shallow six grooved rifling as
opposed to the "normal Smith" rifling of five groove deep rifling.
2 - My bullets are sized to match the throats of my 625-6 (with 5" barrel) and the 625-8 JM Special - .452". They shoot, on demand, under an inch
at 25 yards whether driven at target velocity (4.0 grs. of Bullseye or equivalent) or 1000 fps. with a charge of Unique. The hotter load is my choice for general field use for small game and varmints. I have worked with the NOE version of the Lyman 452424 (250 gr. SWC) getting 900+ fps that should work just fine on hogs and deer at reasonable ranges (my deer have all been taken with the .44 Mags).
3- One thing I apparently need to emphasize is that when reloading, it is CRITICAL when using lead bullets to seat and THEN crimp. I taper crimp on lead bullets without a crimp groove to a case mouth outside diameter of .470".
4- The 1917 S&W revolvers were designed to headspace on the case mouth when using the .45 ACP cases. That meant that the loaded rounds would work without using the supplied "half moon clips" on an emergency basis. When World War II ended, the S&W civilian revolvers also maintained that property (headspacing on the case mouth).
5- In the past few years, S&W has completely changed the specs on the .45 ACP chambers for the 625 revolvers. Now, they are NOT intended to be used with .45 ACP ammo without the clips. You will most probably have ignition problems (failures to fire) without the clips. This was bitterly fought against by the experienced "old guard" at Smith but was instituted anyway. From a personal standpoint, I have no issue with that. My 625's shoot so consistently well with a variety of cast bullets, that the recent changes regarding to headspacing and the change in "ball seat" of the cylinder mouths work well FOR MY USE.
Hopefully, the above will clarify some of the issues. I can recommend a more in depth discussion of these items in Brian Pearce's article in the
Handloader magazine in the January 2009 issue (#257). Further, a more uptodate article of heavy loads in the .45 Auto Rim in the Handloader Magazine #306 (February 2017) I find quite useful.
Dale53
NOTE: I use Lee carbide dies for the .45 ACP/.45 Auto Rim. The issue crimp die has an insert to taper crimp. It works beautifully. However, the heavy bullets (NOE version of the Lyman 452424) has a crimp groove and needs a regular revolver roll crimp. I called Lee to ask if the .45 Colt crimp insert will work in the .45 ACP die. The Lee Technician told me it would but that it is shorter than the .45 ACP insert and requires a special spacer to use with it. Both the roll crimp insert and the spacer cost something like $7.50, as I remember. That is small change, for sure. The spacer and insert works perfectly. I can swap them without removing my die body from the Dillon 550B tool head. Easy/Peasy! I can recommend this without reservation.
rdm
Clarification:
I use the Lee Factory Crimp Die (that’s the die with the crimp insert). I don’t want to mislead anyone. When you exchange the taper crimp insert for the roll crimp insert, as I stated above, you will also need a spacer. When you talk to Lee you have to tell them you want both. rdm