mcb
Member
I would bet that the barrel on a S&W 625 in 45 Colt and a 625 in 45 ACP use exactly the same bore and groove diameters (assuming similar vintage, S&W has change barrel machining tech a few times over the years). I believe that size difference you commonly see is because 45 Colt more commonly uses a lead bullet and common practice is to over size lead bullets ~.001 over groove diameter hence the reported .452. 45 ACP which in predominately a jacketed bullet cartridge is list at groove diameter. But if you running a lot of lead you're probably going to slug the cylinder throats and barrel and make sure you got the right size. Also remember the 45 Colt was originally .454 diameter bullets though nearly all modern makers are using .451 groove diameter now.
I managed third yesterday in a revolver only "USPSA-style" match at my local club with my 625 in 45 ACP. I was less than 4% behind the winner a Master revolver shooter shooting an 8-shot custom 627 and second place was an un-classified (though GM in four other divisions) also shooting a 627 8-shooter. 6 stages, 75 rounds fired, total elapse time was slightly over 63 seconds with 7 reloads (two more than 1st & 2nd place) on the clock. The 625 in 45 ACP is simply a fun revolver to run.
ETA: A quick look over at SAAMI's website show that 45 ACP and 45 Colt have the same SAAMI specification for bore and groove diameters. .442 +.004 bore diameter and .450 +.004 groove diameter. Most manufactures hold tighter tolerance than SAAMI publishes and then tend towards a max material condition. I would bet that most manufactures are running the tolerance down to +.002 if not tighter.
I managed third yesterday in a revolver only "USPSA-style" match at my local club with my 625 in 45 ACP. I was less than 4% behind the winner a Master revolver shooter shooting an 8-shot custom 627 and second place was an un-classified (though GM in four other divisions) also shooting a 627 8-shooter. 6 stages, 75 rounds fired, total elapse time was slightly over 63 seconds with 7 reloads (two more than 1st & 2nd place) on the clock. The 625 in 45 ACP is simply a fun revolver to run.
ETA: A quick look over at SAAMI's website show that 45 ACP and 45 Colt have the same SAAMI specification for bore and groove diameters. .442 +.004 bore diameter and .450 +.004 groove diameter. Most manufactures hold tighter tolerance than SAAMI publishes and then tend towards a max material condition. I would bet that most manufactures are running the tolerance down to +.002 if not tighter.
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