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DA revolver frame lugs

This is a discussion on DA revolver frame lugs within the Double Action Revolvers forums, part of the Handgun Forum category; I mean the bump on the frame below the cylinder latch that stops the cylinder from sliding completely off the crane when open. I noticed ...


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Old 03-18-2017, 09:31 AM   #1
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DA revolver frame lugs

I mean the bump on the frame below the cylinder latch that stops the cylinder from sliding completely off the crane when open.

I noticed that the SP101 is the only Ruger revolver to have it. The GP100 doesn't have one, and since the SP is a "shrunk" GP, you would think the SP wouldn't, either. The Redhawk doesn't, neither do the old Six series Rugers.

I find it disconcerting that a small bump that overlaps the cylinder by maybe 1/32 inch is all that keeps the cylinder off the floor when you open it. Most if not all S&Ws have this lug, and I've heard of it being a problem with wear over time.

I can just assume that the SP is a 28 year old design, and they've changed a few things over time but kept the lug. Ruger must think it's okay.

EDIT: It's not shown clearly in the manual but the GP100 and other Rugers have two spring loaded balls at the front of the crane, that ride in a groove inside the cylinder. The cylinder snaps on, and off, those balls. I've also learned that I need a special tool to disassmble the cylinder, to clean things or get at the ejector spring. It's ordered from Brownell's.

Last edited by bearcatter; 03-23-2017 at 08:17 AM.
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Old 03-19-2017, 08:01 PM   #2
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The GP is unusual in that the ejection rod is offset from the center of the cylinder, if I recall. This allowed more meat in the frame under the barrel, a problem with K frame S&Ws using hot magnum ammo. Being castings I would expect the Ruger to need more material in that area. I am not familiar with the later Ruger DAs but that difference might be part of it. The S&W system has worked pretty well for 120 years so it does not worry me much. The leg used to be staked or riveted in place and was replaceable but I think it is now cast into the frame.

I did have a small problem with the lug on my Mod 25 in .45 ACP as the lug did not clear half moon clips. I took it to a gunsmith to relieve it slightly but he relieved the wrong surface so the cylinder is a bit loose. I don't have a problem as I only use full moon clips or auto rim cases now but I may get it replaced some day just for esthetics.
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Old 03-20-2017, 05:08 AM   #3
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Oh you have to love it when you pay a gunsmith to screw up a classic revolver.

BC that was part of the design that has proven itself after 30 years.
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Old 03-20-2017, 05:52 AM   #4
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Originally Posted by Terry_P View Post
Oh you have to love it when you pay a gunsmith to screw up a classic revolver..
This why I became a gunsmith . I would tell them how I want my gun and when I got it back it was wrong or not done correctly and screwed up too boot .
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Old 03-20-2017, 07:18 AM   #5
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Originally Posted by Machinist View Post
The GP is unusual in that the ejection rod is offset from the center of the cylinder, if I recall. This allowed more meat in the frame under the barrel, a problem with K frame S&Ws .
The SP is just a reduced size GP. On both, there is a latch on the crane, and that offset ejector rod does nothing but eject cases. Just seemed odd that only difference in the two guns is the cylinder retention.

Your Model 25 "fix" had to be irritating, to say the least.
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Old 03-20-2017, 08:50 AM   #6
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The GP preceded the SP by three years, so, knowing Ruger, I am actually NOT surprised there are differences in the way the two are engineered. For sure, the GP influenced the design of the SP, but I think there is more to the SP's engineering than just shrinking a GP, just as there is more to the GP's engineering than just beefing up the earlier Security Six.

From what I can see, Ruger would have had to do more than just shrink a GP to make the SP competitive with steel J frame Smiths. My best guess is that the lug on the SP is a way to keep weight and frame size down, down, which probably explains some of the other differences in SP versus GP design, such as the beefy top rib on the GP that allows you to switch out front sights via a plunger in the rib, something I wish you could do on the SP, but, again, that would mean more weight. As it is, the 4.2" barrel SP is already pushing 30 ounces. Even the 2.25" SP still has trouble competing with the steel Model 60 which weighs almost 5 ounces, less. After all, you can only go so thin on investment cast frames that Ruger uses, so something else had to go to get SP weight down.

My explanation, for what it's worth, anyway.

Last edited by north country gal; 03-20-2017 at 09:17 AM.
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Old 04-05-2017, 09:55 AM   #7
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Originally Posted by north country gal View Post
From what I can see, Ruger would have had to do more than just shrink a GP to make the SP competitive with steel J frame Smiths. My best guess is that the lug on the SP is a way to keep weight and frame size down, down, which probably explains some of the other differences in SP versus GP design, such as the beefy top rib on the GP that allows you to switch out front sights via a plunger in the rib, something I wish you could do on the SP, but, again, that would mean more weight.
Wow, three replies out of over a hundred views. Thanks!

I don't think the GP's ball bearing cylinder retention would have added more than an ounce or so to the SP, worth it for a better design. I think that the machining, being more difficult and costly, would make for a smaller gap between the SP and GP price. And Ruger didn't want that.

The 4.2 inch SPs, .22 and .357, having a top rib, have enough space at the muzzle to have the front sight plunger. I had thought about that, too.

I'm sure my SP frame lugs will outlast me, and I don't need a changeable sight on the .22. I just hate to see a good design that could have easily been better.
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