The lower lugs on my RIA barrel are showing wear marks on the corners, apparently from contact with the slide stop pin. I assume this is bad... very bad. The gun has about 2500 rounds through it and never jams.
Is this something that can be fixed by taking material off the corner with my trusty dremel? Should I be concerned that the link / pin may be weakened or damaged??
Assuming the areas you're referring to are those circled in red here...
...just use a file to dress them down until pin contact is just barely eliminated. Don't use a Dremel unless you're really good with one - too easy to take off too much.
Edited: If the web between the holes in the link measures less than 0.097" you should also replace the link with a standard 278 link.
Great! Thats what I was hoping to hear.
I will break out the small file set.
On MY monitor, that link looks very long in the hole. Nice resolution. What do the top lugs of bbl and slide look like?
I inspected the top of the barrel lugs carefully and could not find any signs of wear. The edges of the lugs are clean with no rounding evident. The slide did not have any apparent wear either. I do plan to go ahead and replace the link anyway with a wilson for added insurance.
If Berkbw's observation is correct and the link's big hole is elongated, be sure to replace the link before filing on the lugs. Could be the knees got beat down because the link got worn or was made funny.
Be sure to drive out the link pin and inspect it... you may need to replace the barrel if there is damage to the pin, if not only the pin.
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Be sure to drive out the link pin and inspect it... you may need to replace
the barrel if there is damage to the pin, if not only the pin.
Could you please rephrase this? Maybe it's because it's too close to my bedtime, but I'm not sure what you're saying.
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Could you please rephrase this? Maybe it's because it's too close to my
bedtime, but I'm not sure what you're saying.
Looking at the Kuhnhausen Diagnostic Chart, it indicates that if there is bottom lug damage, to check for a broken link pin, and if it's broken to replace the barrel if needed. Is this not correct?
I thought that "knee bump" was a serious issue. Is this not "knee bump?" I'm sorry if I caused any confusion...
OK, now I see. Good call.
Knee bump is serious, but I'm thinking the "bottom lug damage/broken link pin/replace barrel if needed" sequence would apply if the lug was damaged and the link pin (or link) broke because the barrel didn't hit the VIS first when linking down.
If the lower lugs aren't cracked, I think this situation falls more into the "Bottom lug bind" sequences which follow in Kuhnhausen. And because this binding occurs when the link is in compression with the barrel going into battery, I don't see how the lugs can be cracked this way.
But now that I think of it, the slide stop's pin should be checked to make sure it hasn't gotten bent by the impact with the lower lugs as the barrel is on its way into the battery position.
BTW, I've seen this issue on lots of Philippine-made guns (MetroArms and Armscor both) including my RIA. Not sure what the deal is, but I don't think it likely you'll need a new barrel.
Since this happens on the trip to battery - what kind of springing would this suggest?
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Since this happens on the trip to battery - what kind of springing would
this suggest?
Not sure what you mean by "springing", but the link going from compression (for the first little part of the way to battery) to tension (if the link pulls the slide stop pin against the knees) comes to mind.
But that peening of the knees can occur without the link going into tension if the knees are not too badly mis-shaped in that area. Peened just from the impact when the knees hit the slide stop cross pin. The average 1911 has 0.0075" of total play between the link pin and slide stop cross pin, so knee peening does not necessarily mean the link has gone into tension and bound the slide stop cross pin against the knees.
If that made sense, is that what you were asking about?
FWIW, I showed this to people at school and an instructor, and the consensus was that this is the most serious instance of knee-bump they've ever seen. The dwell time (determined by the flat part on the bottom of the lugs where the lugs ride over the slide stop) may have been decreased which is NO GOOD.
If this were my gun, I'd replace the barrel.
Thanks for the additional insight on this. The slide stop appears to be in good shape. I have my eyes on a new wilson drop in barrel and new link / pin from Midway. I don't need much prodding to buy new parts for my gun!
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I have my eyes on a new wilson drop in barrel and new link / pin from
Midway.
Good deal. Good parts installed properly will last a lifetime. The RIA and other Philippine guns are good value for the money, but they're not without need for better components. Hope your new parts work out much better for you.
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If that made sense, is that what you were asking about?
I was remarking on the incredible damage done to the muzzle side of the lugs. Which, I think, can only come from a crash against the SS whilst in search of battery - probably propelled by a recoil spring.
I can't imagine doing that with a hammer, let alone a flimsy spring. I just assumed ( I KNOW!) that you had not seen something as that before. Sorry.
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Good deal. Good parts installed properly will last a lifetime. The RIA and
other Philippine guns are good value for the money, but they're not without
need for better components.
...I have already installed many Wilson parts in this gun, they all seem to fit with little trouble. Hopefully the drop in barrel will "drop in".
I have run up to an 18.5 lb spring. Now running a 17 lb. The only malfunction I ever have is an occasional last round FTRTB, which I blame on the magazine (follower letting the last round go free), not the gun. When this happens the slide is about about 1/8th inch from being in battery with the extractor jammed against the case rim. Not sure if this is when the impact on the knees may be is happening.
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The gun has about 2500 rounds through it and never jams.
The flat areas on the lug radius are probably not be due to the s.s. pin banging into it, but rather to a crude factory fix to prevent the bumping from happening in the first place. The clue is that the gun never jams, and that the marks do not appear to be shiny in the photo. The way it looks to me is that the lug radius was filed that way to prevent the problem in the first place. If you install the s.s. pin into the link and move it along the lug radius, it should be obvious which of the 2 possibilities is most likely.
To continue, I recall many discussions on the forum about whether the barrel lugs radius actually ride the slide stop pin as the barrel goes into battery. I believe that the answer was that in an ideal world it would happen, but it is rare and requires an experienced barrel fitter to achieve it. Any interference, however, is going to show up right away as misfeeding, failure to RTB and so on, and it seems the gun is not having those problems.
Having said as much, many barrels will show a shiny or even partially flattened spot in this general area, although nowhere near the amount in the photo. Most of the time that shiny spot is not due to lug interference, but rather to too much clearance between s.s. and lug. The slide works up enough speed to cause the s.s. pin to smack the radius as the 2 parts first come into contact, then everything continues on into battery. In that situation, filing the shiny spot on the lugs just widens up that initial gap and the spot will mysteriously keep showing up. Just my opinion.
I agree with you Lazarus on the crude factory fix issue. And that the gun never jams due to the appearance that the front of the lugs are not contacting the SS. And I think niemi24s is right that the radius should be smoothed... if nothing else it will look better. But, I am confused about what you said about the barrel lugs radius riding the SS pin as the barrel goes into battery... don't the barrel's lugs have to ride the SS pin at some point so that the barrel's bottom lugs can push the barrel's top lugs into the slide?
Sorry I am confused?
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...doesn't the barrels lugs have to ride the SS pin at some point so that
the barrels bottom lugs can push the barrels top lugs into the slide?
I thought the link height did that.
Hi RKV, what your refering to is the practice of "link binding" the barrel into the slide. This is not a common practice but it is done regularly. IMO it is not the right way to do things. The links only job is to pull the barrel out of battery as the slide goes to the rear.
I certainly entertain comments from others here. I have built a number of 1911 but I certainly do not consider myself and expert and I always want to learn.
So the little radius at the bottom of the barrel lugs (at top stroke) pushes the barrel up into the upper lugs at the same time as the link itself acts like a chain that prevents the slide from flying off of the gun?
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Sorry I am confused?
No, the lugs do not have to ride SS pin at some point - or at any point, for that matter. The only mandatory contact between the barrel lugs and SS pin occurs at battery when this contact halts the barrel's forward motion. This is how the average (mid-spec) Gov't Model 1911 is in battery, and its lower lugs are above the SS pin by almost 0.010" as shown here:
PICTURE 404
In this gun, the SS pin never comes in contact with the lower lugs until the battery position is reached and in battery the barrel is supported vertically by the link (which is what keeps the lugs up off of the SS pin).
NM barrels (or those with oversized lower lugs) can be fitted two different ways for the trip from linkdown to battery. They can...
* ...ride the link up to the point where the link is vertical. At this point, the vertical support of the barrel is transferred from the link to the lugs SS pin and the barrel lugs slide along the SS pin for the remainder of the trip (about 0.042", IIRC) to battery.
* ...ride the SS pin all the way from linkdown to battery, with the link never going into compression.
And if the NM lugs are properly cut, the SS pin supports the barrel such that the barrel is all the way up into maximum locking lug engagement with the slide.
All that makes for 3 different ways the barrel can get to battery.
Thanks niemi24s, I knew the perfect answer was out there. Do you agree that the link should not push the barrel into the slide? I can't see the link pin taking that kind of service for very long.
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The link's only job is to pull the barrel out of battery as the slide goes
to the rear.
This is a myth that will probably never die.
"A myth?" you ask? "Certainly!", I say. Read what JMB himself says about the link in his patent for the Model of 1911:
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...the link itself acts like a chain that prevents the slide from flying
off of the gun?
No. What keeps the slide on the gun is the barrel. And the barrel is kept on the gun by contact between the SS pin and the two downward projections (aka, feet) on the back of the barrel's lower lugs.
I wonder why the original post didn't include a photo of the ss along with the lower lug image? That would help my less than experienced eyes at least.
I bet Berk was right about the link being stretched or oversized too. I've seen barrel lugs being fitted and the only other idea I had was that the fitting just never happened before the barrel was dropped in.
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Do you agree that the link should not push the barrel into the slide?
I neither agree nor disagree. It all depends on the individual gun and the resources available. In the olden days before it became common practice to weld up lower lugs for fitting (and before NM barrels made with oversized lugs became available), it was common practice to long-link a 1911 so the barrel was held up as high as possible in the slide.
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I can't see the link pin taking that kind of service for very long.
The link's in compression when doing that and I don't know if it's even posssible to cause a link to fail by putting it into compression in a 1911. Tension? - yes, certainly. Compression? I think something else would break before the link even broke a sweat in compression!
Besides, even if the link's in a fair amount of compression when vertical on the way to battery, any compression's relieved during the last 0.042" of the trip.
And that's the major problem with accurizing a 1911 by long-linking. While it can take a lot of the vertical slop out things, it can't reduce it to zero - due to the link rotating past its vertical position. That "relaxation" amounts to nearly 0.003" as shown here:
PICTURE 404
[Edited: And after all that blather I belatedly notice you said "link pin" - not "link". Methinks the SS pin would bend long before the link pin would shear.]
...an informative discussion to be sure. Reams of information will pop up on a search for "riding the link". As it turns out most guns operate that way even if it is not the ideal. Sometimes the lower link hole is enlarged to compensate for other problems. Another variable to keep in mind.
With so many aftermarket parts and widely varying dimensions, it is difficult to predict how close to the ideal you can come even with a lot of hand fitting. As far as what stops what, the above diagram shows how the slide stop stops the barrel. The barrel then stops the slide because the upper lugs are meshed into the slide recesses.