Puzzling 1911 question

[critter]

I recently bought a new Ruger 1911 Commander size. When I broke it down, I found that the shaft to the slide stop has a small flat most of the way across it.

Dealer had a second one in stock (full size) and it is the same so it is purposeful apparently.

Anybody know the purpose of that feature? I never saw it on any other 1911 and I've seen a lot of them of all different brands.

Thanks.

 

[David E]

If I understand what you're saying, the slide stop doesn't protrude much, if at all, past the frame on the right side.

If so, the reason is to keep the slide stop from being nudged out, ever so slightly, to the left side. If that happens, it misaligns just enough on the left side to invisibly cause jams. You'll look at the jammed open slide in befuddlement, as the jam just doesn't "make sense." The usual remedies don't usually work, adding to your confusion. Push in the slide stop from the left and suddenly all is well.

It affects lefties more often, but it can happen to righties, as well.

It's a good preventative feature that all 1911's should have. Several of my 1911's have been so modified.

.

 

[critter]

I understand the flat tip of the shaft for the reason you mention.

However, what I'm talking about is that the shaft is flat underneath along most of its length but not quite to the left end. I can see no reason for it, but I'm sure there must be one.

 

[JTQ]

Is the flat side facing the magazine? Probably there for bullet nose clearance.

 

[rcmodel]

Except, the bullet nose doesn't come anywhere even close to the slide stop pin.

I don't have a clue why Ruger would put a flat on a slide stop pin though.

rc

 

[Jim Watson]

Where on the shaft, relative to its position in the gun?
Top, bottom, front, back, angled?

A picture would help.

 

[Walkalong]

Mine are all round, various makers, but no Ruger, or I'd check.

 

[Mike J]

My understanding is that all the black bits on the SR 1911 are MIM. My hunch is that Ruger thought that no more material was necessary than what they put into the pin. I would think that is why they made it the way it is. Of course I could be wrong. After all the SR 1911 is my first & only 1911 type pistol.

I thought I would provide a pic of the bottom of the part in question though.

 

[1911Tuner]

It's reminiscent of what was known as the "Marine Corps Cut" done on their match pistols, and...along with the manner which the lower lugs were cut...provides more surface area for the lower lug to sit on and enhances barrel stability in battery.

Since it's in the same place, I suspect that the reasons are the same. A side picture of the lower barrel lug may confirm it.

 

[Mike J]

Tuner I took a pic of the field stripped parts last night. Here it is if you need a closer pic with more detail let me know I will see what I can do. I'm pushed for time this a.m. Gotta get to church with the kids.

 

[1911Tuner]

Need a close-up of the lower barrel lug to see if the flat on the crosspin matches the lower lug.

From what I see...it doesn't...so there was no real advantage in creating that flat.

 

[critter]

Mike, thanks for the pic. Mine is exactly the same in size, location, length and even the little stamp on it.

 

[Mike J]

Here are a couple of pic's of the barrel lug. Maybe one will give enough detail. I'm not the best photographer to start with & all of these are taken with my phone.

 

[Mike J]

BTW my pistol is the 5" government but I would imagine it & the commander are made the same other than slide/barrel length & spring strength.

 

[rcmodel]

Put the pin back through the barrel link, and hold it in the position it would be in the gun when the slide is in battery.

So, is the flat on the pin matching up with anything on the barrel lugs???

I can see no finish wear in your photo of the pin.
So doubt seriously the lugs are locking up on it.

rc

 

[Greg528iT]

The flat on the pin is on the bottom, farthest away from the barrel and lugs. The flat on the pin has no relation to the barrel lugs.

My guess is.. if I wanted to size the pin as close to the frame hole size as possible, a slight flat would reduce your pin to hole contact from 360 deg to say 300 degrees.. it would slide in a bit easier, then get full engagement that last little bit.

 

[Mike J]

RC & Greg I believe ya'all are right.

 

[rcmodel]

if I wanted to size the pin as close to the frame hole size as possible, a slight flat would reduce your pin to hole contact from 360 deg to say 300 degrees..

Maybe.

But it would also wear the hole out oval much faster then a round pin!!

Anyway, his is not flat on the side that goes in the left side of the frame.

Only the side that sticks through the right side of the frame.

And that would cock the pin sideways in the frame under load, and make the pin hole wear factor even worst!! :banghead:

rc

 

[1911Tuner]

The flat on the pin is on the bottom, farthest away from the barrel and lugs.

It is. Dang. I wasn't lookin' at it right.

 

[Greg528iT]

But it would also wear the hole out oval much faster then a round pin!!

Anyway, his is not flat on the side that goes in the left side of the frame.

Yes the right side frame hole, may wear to an oval faster. As you saw and I the left is fully round.. It should have a full contact pattern.

I guess I should have said.. One reason I can see for the flat is,

 

[Rock185]

critter, I don't have a SR1911, but have owned a bunch of other manufacturer's 1911 type pistols. I wouldn't be surprised to learn that the flat is there to insure the MIM/mold mark is below the level of the rest of the rounded portion of the slide stop surface, to insure the MIM part will fit into the gun. The closest thing to that I have ever seen on any slide stop, factory or aftermarket, was with a new Springfield Loaded I had. The MIM slide stop had what I can only describe as flashing ( like a part out of an old plastic model kit) across the entire length, but on top of the pin. Now that SA MIM part may have been the most durable, precise and all-around wonderful slide stop ever produced, but not to me. I pitched it and replaced it with a Wilson Bullet Proof bar stock slide stop, that was was actually round...ymmv

 

[critter]

Rock, that makes sense as there certainly is a 'mark' of some sort on the little flat.