Interesting Problem With 45 Auto Rim Brass

[JMax]

I got an S&W 1950 that has had some AR brass bind up when I shoot in DA. It does not bind in my 25/17. It appears that the hand is binding on some case rims. I measured case rim diameters and found that diameters ran from .510” to .514”. I took cases in .001” increments and off to the range. No binding at .511” or less, binding starting at .512” and really tight at .513”. Approximately 60% of the cases were .511” or less now I have started trimming the rest.

[Nueces]

Good info for us who have Smith 45s. I have not run into that problem with Remington brass (my Starline cases have not yet been loaded) in any 1917, M26, M25 or M625, but I like the way you ran the cause down. And I'm curious about how you are smallifying the case rims: details, please.

[JMax]

I have all StarLine brass. I am using a bastard file with safe edge or smooth sides with the brass or loaded rounds gently chucked in a half inch battery powered drill. Dial calipers are locked to .510” as a go no go gage and check after 5 firm strokes with the file. And repeat a couple of strokes if the cases don’t pass and retest.

[JMax]

Included are photos of what happens when the case sticks out too far when one starts to trim the rim and the second is a photo of the proper max depth to trim with a safe edge file.



Additionally distance from the center pin to the hand window farthest from the center pin comes interplay as the hand in DA can be trapped or bind if the case rim is too large in diameter between hand, ratchet and case rim. Basically tolerance stack up. Try empty cases with the largest rim diameter pulling the trigger DA ad see if you revolver binds.

[JMax]

Today I went to the range with 48 rounds with 5 that had case rim diameters of .511”+ to .512”+. During shooting I had binding with those salted rounds all others were like silk in DA. The max rim diameter for 45AR is .516” so those would not work in my 5 screw 1950 without trimming. Problem solved.

[Der Gebirgsjager]

Very interesting, JMax. Another confirmation of the saying "No two things are exactly alike." I've got 5 AR-capable revolvers, and never had that problem.

DG

[243winxb]

The rim diameter may keep growing? Had it happen in 45 acp, S&W 645 auto, with a hot load of BlueDot.

When i tried to fire the same brass in my Colt Gold Cup with target loads , the rim was to wide to slide up the bolt face. Caused jams.

[ddixie884]

I have owned numerous .45acp revolvers and never had that trouble. I think yours may have closer tolerances than any I have ever owned. Hope you get it all sorted and get reliability..........

[JMax]

I campaigned a 4” and a 6 1/2” at Second Chance for years, had a 625, two 1917s and the current early 5 screw 1950 and it is the only one to exhibit this issue. I got it for a song as it had been dropped, had yoke alignment problems, end shake, ejector rod had excessive runout and the cylinder was rubbing against the barrel. Straightened everything out with no end shake, headspace is .063”, BC gap is .004”, ejector rod runout is less than +/-.001”, plugged it and every cylinder chamber is centered on the barrel and barrel throat is at minimum. It shoots like a dream now so I write it off as tolerance stack up and I have trimmed all of the AR rims to eliminate binding.

[StrawHat]

…I campaigned a 4” and a 6 1/2” at Second Chance for years, had a 625, two 1917s and the current early 5 screw 1950 and it is the only one to exhibit this issue…

It shoots like a dream now so I write it off as tolerance stack up and I have trimmed all of the AR rims to eliminate binding...

You have not posted a photograph of the revolver, are you talking about a 45 ACP Model 1950 Military or 45 ACP Model 1950 Target?

Kevin

[joatmon]

Sounds as if something else got out of spec. when dropped, hand bent or?
Aaron

[Golfswithwolves]

Mr. JMax- Make sure that your ejector bolt is screwed in all the way. Mine loosened up in my 1917 S&W revolver and bound up the action. (I like simple and free solutions)

[Polymath]

Try chucking up a wooden dowel then putting the case onto it. Saves collapsing the mouth.