So lets see.
Got antsy last night while the wife was watching her recorded shows. Had zero interest in America Has No Talent or 90 day finance me.
So I played around a little bit.
Cut open a few cases to see the difference in case capacity. Load data for 255 gr isn't readily available,so I got that going for me. One of the older speer manuals might have something for 260 gr, but thats about it. Internet searches reveal a lot of the same stuff, so here we go. Case capacity is similar, but not exactly the same.
27.4 drops of water for the a.r., 27.3 d.o.w. for the a.c.p according to one of the articles above (graciously provided by Mr. Spangler).
From left to right are-
Black hills, or reloaded black hills, 255gr in Auto-rim. These things are stout, but 24 or so fired without issue, so I'll use that as an o.a.l. baseline.
230 gr rnfp (.452) .45 acp set to 1.230, which has worked pretty well for me so far in about everything I own chambered in .45. Haven't tried it in the 97B yet.
255 gr rnfp .45 (.452) acp set to 1.230. Might be a touch longer, but you see where I'm going.
Note the difference in usable space.
I didn't cut open an auto rim case, but take a look down towards the case.head of the acp. As it gets thicker, it doesn't jive so well with the much longer 255 and the case mouth starts to flare out.
I could pull the Auto rim and weigh the powder charge, but not knowing what powder was used, all I could do is try to figure out what it displaces at, and try to find a similar displacement with a powder I have, and then weigh that. This is where those yellow Lee spoons would come in handy. Project for another day.
Because these will be strictly for the 625, lets see if we can plunge a caliper end down and measure throat length.
This is extra yucky, and weave some leading.
I don't have a pic of the forcing cone, but take my word for it, its extra yucky.
625's are famous for having throats of varying sizes. All smiths are famous for having horrible finish work.
I like smiths. I have 5 of em. But these are kit guns at best.
I knew this was going to happen, so I ordered a throat reamer.
Tough to tell with all the schmeg, but the goal here was to see how close the acp sits to the edge of the throats.
Time for a scrubbing.
After a few mins with some chemicals, a bore brush and a cordless drill, I can sort of see exactly where the acp's sit (moon clipped) in relation to the throats..
If they're not right against it, then its real close, which is fine. I wasn't expecting a lot of jump like .38 spl in a .357 cylinder.
Full disclosure- I am not a gunsmith. I will not pretend to be.
I'll chime in every so often on things I'm familiar with on what I own, but thats about it.
I am also not a machinist.
What I do have is about 28 or so years under my belt as a med/hvy duty mechanic. Which reminds me, I need to recert my master status, but can't get in till Oct cause of the 'Rona. So I have a pretty good idea of how things should work..
Lets cut some throats.
I grabbed a finish reamer from Brownells, and a pilot kit.
This one cuts to .4525. The pilots vary in diameter and go up to .4510 incrementally.
This is where you-tube comes in handy, because a lot of time the manufacturers of various tools will put a vid up explaining exactly what to do.
I once watched some guy fit a 1911 slide to an over sized frame with a mallet, a vice and lapping compound. Don't be that guy.
Indexing the throats is easy. Take a pilot, see how it fits in that throat, write it down, mark that cylinder, and go on to the next one.
Throats varied between .4505 and .4510. Which would explain the leading on a few of the cylinders. So I'm wondering at .452, would the coating peel off in the .4505 throats.
Required zero downforce to cut these. The weight of the tap handle was enough. A little cutting oil and away we go.
Throats are cut
This is where a cylinder hone comes in handy to take out any chatter marks.
I do not have one that size.
So its a wooden dowel, some 1200 grit wet sand paper, and then ultra fine scotch-brite pad and some metal polish.
I don't need a mirror shine.
No pictures for that process. Metal polish gets everywhere and I used a lot of it. Add a cordless drill and the end result is probably what a porn shoot gone horribly wrong looks like.
Heres the end result of that.
I can see the cases reflecting in the throats, and for me and what I'm doing thats good enough.
And the fired cases dam near fall out of the cylinder under their own weight, so thats a plus.
Next up is chamfering the cylinder.
I'll probably just get the master handgun kit from brownells because I have 5 cylinders to do (.22, .38/357/, .40/10mm and .45) and its less expensive than buying them each individually. And I'll ream those throats too, just not today.
I should have brought one of those 255's to see how they fit int the throats, but forgot to. I'll check it tonite.