New RIA that may be a little too loose, barrel/slide fit concern...

[uglygun]

Preface, I was posting this in the RIA forum to see if anyone else has has noticed something similar with their RIA gun, though I didn't state it with the original post as my main concern was trying to accurately describe my concerns and plum forgot to state why I was posting and where.

Yes, this has gunsmithing/troubleshooting questions relating to the function of the pistol. However I wasn't about to multiple post the same thread into multiple forums, so thanks to the moderator who moved it. Atleast now there is a link in the RIA forum pointing to this thread which may lead one of the RIA folks here to see this and give their opinion on the issue as well.


Got a new 1911A1 home today from the shop and was going over it with a fine tooth comb.

Checking the slide and barrel it looks like there is zero engagement on the 2nd and 3rd lugs of the barrel, I understand that these parts can come together and mate once the 1st lug wears/mates to the slide a bit. I have no way of accurately measuring the 2nd/3rd lugs but with calipers I'm fairly sure I've managed to measure the 1st lug.

And here is my concern, distance on the slide from the breech to the first lug engagement is right near 1.325-1.326.

Barrel measures from the back of the hood to engagement surface of the first lug at 1.313-1.314.


The area of concern right now is that when the gun is assembled the engagement between the first lug of the barrel and the slide isn't happening... Barrel/slide is in contact at the breech/hood yet there is a visible gap between the front of the first lug and the opposite mating surface of the slide. For these two parts to have any engagement the slide has to travel rearward approx .01 inch.

My concerns are that because the tolerances are opened up to the point they are that eccessive lug battering may take place, it would appear to me that upon firing the slide will come back nearly .010 inches before engaging a lug.

Note, this is a hard thing to see at the shop when the pistol is caked in lube and the lighting is less than ideal. However after getting it home and dried off it's a bit easier to notice(especially in comparison to another 1911 which is tight).


The 1st lug does show signs of engagement but it's a very small amount of wear by comparison to another 1911 I own, understanding that this is a pistol with minor amounts of test firing so the signs should be fairly limited. However, with only the first lug showing signs of engagment as the pistol wears in the tolerances I'm concerned about seem like they'd only grow larger and raises the question of whether the 2nd/3rd lugs will ever wear in(understanding they are of lesser importance).

With the recoil spring removed, holding my thumb on top of the barrel to keep it motionless in it's lock up position, I can get an idea of the amount of play between the slide/barrel. It does appear to have around .01 inch of play from where the spring forces the slide to come in contact with the rear of the barrel's hood and then rearward slide movement to where the lugs engage as tehy would during recoil.

Compared to my Para Ordinance which I've had for nearly 9 years and probably 4k rounds through it, a similar check with it results in maybe .001-.002 total movement.


Basically, waiting to see what people with a couple years of smithing experience have to say on this. I understand that tolerances are expected to be a bit more loose. However I don't have the experience to know if this is excessive to the point that it will compromise safety or durability.

I'd say I have a fair working knowledge of the 1911 but not a mastery of it. Enough to do basic maintenence and maybe even some trouble shooting but not enough to avoid getting myself into trouble if I were to do a complete build from the ground up.

The pistol currently sits unfired, just brought it home today and will possibly take it out tomorrow to run some rounds through it. Now I'm questioning whether I should do that or not.

Thinking I'm gonna need to be giving a call to RIA/Armscor sometime next week.

[pa_guns]

Hi

At least *one* lug must be engaging or you would observe the result :D

A little bit of clay should quickly show you how much distance there is before the second and third lugs engage.

Bob

[uglygun]

Hi

At least *one* lug must be engaging or you would observe the result :D


My concern is this, the contact currently being made is between the breech/hood and the feet of the barrel/slide stop. With what seems to be either an over size tolerance on the slide or undersized tolerance on the barrel.

For engagement to be made between the barrel lugs/slide lugs, the slide must move rearward what appears to be very close to .01 inch while the barrel remains stationary. Once the slide comes rearward the required amount, then you can see the engagement between the first lugs being made.

This relative "slop" is what concerns me as I can imagine it only getting worse, not better, as parts begin to mate together during firing.

Most of the 1911s I have experience with are on the tighter side of tolerances with friends in 3 gun and having generally handled higher dollar 1911s from the popular manufacturers.


Figured out how to measure the tolerances that I'm concerned about.

With the recoil spring removed, pulling slide forward brings the barrel/breech into the relationship that the spring would drive it to. Measuring from the front of the slide to the front of the frame I have a total measurement of 1.603 inches. Then, placing my thumb over the top of the barrel and keeping it locked in this position, allowing the slide to go slack, the slide moves rearward until contacting the 1st lug, this new distance is 1.584 so it's an even larger discrepancy than I originally thought. Total of very close to .019-.020 inches.

This is movement that comes before any apparent unlocking or actual rearward barrel travel, it's all play in the slide in how it relates to mating to the barrel lugs.

[niemi24s]

What model RIA is this? If it's a "mil-spec" model, here's the specifications for those distances based on U.S. Army, Rock Island Arsenal (not your RIA) blueprints for a USGI (non-National Match) M1911A1:

Slide's Breech Face to Lug = 1.319 +/- 0.006 inch
Barrel's Hood to lug = 1.3005 +/- 0.0055 inch
Barrel's Chamber (rear) to log = 1.152 - 0.006 inch
Barrel's Hood length = 0.149 + 0.005 inch

Don't know what spec's your RIA is built to, but compared to these your slide dimension is right at the upper limit of the Army spec and the barrel is above the upper limit of the Army spec. The fore-aft "slop" spec between slide & barrel in battery works out to 0.0125 +/- 0.0075 inch. The hood does not usually contact the breech face - usually, the chamber (just forward of the hood) contacts the breech face guide blocks. Hood contact is OK, however - depends on the individual barrel & slide.

"Mil-spec" models are designed and built loose on purpose, so they'll probably wear themselves out much quicker than a tightly fitted gun. Almost hate to ask, but, what instrument did you use to take these measurements and how confident are you in them? Regards.

[uglygun]

What model RIA is this? If it's a "mil-spec" model, here's the specifications for those distances based on U.S. Army, Rock Island Arsenal (not your RIA) blueprints for a USGI (non-National Match) M1911A1:

Slide's Breech Face to Lug = 1.319 +/- 0.006 inch
Barrel's Hood to lug = 1.3005 +/- 0.0055 inch
Barrel's Chamber (rear) to log = 1.152 - 0.006 inch
Barrel's Hood length = 0.149 + 0.005 inch

Don't know what spec's your RIA is built to, but compared to these your slide dimension is right at the upper limit of the Army spec and the barrel is above the upper limit of the Army spec. The fore-aft "slop" spec between slide & barrel in battery works out to 0.0125 +/- 0.0075 inch. The hood does not usually contact the breech face - usually, the chamber (just forward of the hood) contacts the breech face guide blocks. Hood contact is OK, however - depends on the individual barrel & slide.

"Mil-spec" models are designed and built loose on purpose, so they'll probably wear themselves out much quicker than a tightly fitted gun. Almost hate to ask, but, what instrument did you use to take these measurements and how confident are you in them? Regards.

It's a RIA 1911 A1.

Thank you for posting the dimensional info, assuming it's the same, will give me something to compare to and will be checking.

As for the instrument, don't have access to a micrometer but I do have access to a set of dial calipers. Tried to take multiple readings from various places to get some consistency(have experience with machine tools) in the measurements on the slide/barrel.

Took me a minute to really try to think of a way to measure the perceived slop though, finally I figured I could measure it at the front of the slide against the front of the frame.

As for the hood versus chamber contacting the breech...

Removing the slide/barrel and flipping it over to watch for contact, it would appear that I could use the same thickness shim to slide it between breech & barrel no matter if it was between the hood and slide or the chamber and slide.


Grabbed the calipers again, measurements of

Slide's Breech Face to Lug = 1.325
Barrel's Hood to lug = 1.312
Barrel's Chamber (rear) to lug = 1.152
Barrel's Hood length = .16, not measured but subtracted from hood-lug and chamber-lug measurements

[vikz]

man you guys are really inspecting your 1911s!! i just usually clean mine and start shooting ...i guess i'm not that picky or i just dont pay attention to details..for me aslong as its clean and it shoots well i'm good to go

[uglygun]

man you guys are really inspecting your 1911s!! i just usually clean mine and start shooting ...i guess i'm not that picky or i just dont pay attention to details..for me aslong as its clean and it shoots well i'm good to go

It may come down to that still if what I am seeing is deemed safe which is my first concern.

Durability being the second concern but not as big as the first. Being in California it's impossible for me to buy frames thanks to the silly Ca. safe handgun approval bill. Part of the attraction to these RIAs is that it gives me what appears to be a serviceable gun with the possibility for future work done on it as my experience grows I may take to doing some limited custom work.

As it stands I'm waiting to here from the rep for RIA/Armscor and get his opinion on this gun.

[niemi24s]

I, for one, would be reluctant to decree any gun safe to shoot that somebody's reported a problem with - whether that problem be real or imagined. Doing this sort of thing in cyberspace cannot ever take the place of having the gun in the hands of a competent 1911 gunsmith for a safety check.

On the other hand, if I even suspected the gun was NOT safe to shoot I'd jump right in and say so.

Sounds like you've had previous measurement experience, so I'd recommend waiting to hear what the factory rep says. They'll probably want you to send it back to them (Aaaargghh!), as they may also be reluctant to say it's OK to shoot without eyeballing it themselves. Good luck. Regards.

[southbound]

You need to talk to Ivan Pm or call.

The link is at the top of the page
Welcome to Advanced Tactical Firearms
Please call us at 775-537-1444

Hope you work it out..

[uglygun]

You need to talk to Ivan Pm or call.

The link is at the top of the page
Welcome to Advanced Tactical Firearms
Please call us at 775-537-1444

Hope you work it out..

10-4

I sent him a PM earlier today requesting he see this thread, not knowing his schedule I left my personal contact info so he can call me when his schedule permits.

[John]

I have a question. How can you tell if the 2nd or 3rd lugs are making contact or not? This gun is new, so it has been fired once or maybe twice. Maybe the first lug is not making contact, but the second may be.

[uglygun]

I have a question. How can you tell if the 2nd or 3rd lugs are making contact or not? This gun is new, so it has been fired once or maybe twice. Maybe the first lug is not making contact, but the second may be.

Primarily two reasons..

First, is pulling the barrel only the first lug shows any signs of having made contact with the other lugs. I understand that the other lugs can come into contact with additional firing as the 1st lug sets in and mates with it's corresponding surface on the slide.


2nd, there is distinct front/back play in the slide if I remove the recoil spring.

I tested for this by pushing the slide forward to full lock up as would be done if the recoil spring were installed.

This is where I confirmed that the barrel hood is making direct contact with the breech and where I noticed the gap between the first lug and the slide as well. With the slide fully forward, I place my thumb on top of the barrel holding it in position, I can then move the slide and feel exactly how much the slide can move forwards/backwards. This is movement that exists before any noticeable contact between the lugs of the barrel/slide and occurs before any movement of the barrel.

Whether the slide makes initial contact with the first, second, or third lug I do not know but it appears to be happening with the 1st lug only given that it is the only lug showing wear that likely came from when it was test fired.


Total movement is roughly .019-.020 inches when measuring the play from the front of the slide to the front of the dust cover.

If the 2nd or 3rd lugs were making contact then this play would be nonexistant or would not permit as much play as I have currently. As it stands, the measured difference between my breech/1st lug measurement on the slide and the hood/1st lug measurement on my barrel corresponds very closely to the total measurement of the gun assembled and measuring the play/slop.


Considering all of that, it's almost definitely the 1st lug that is bearing the full force of any firing as the pistol sits in it's present condition. And if I'm wrong the slide still travels .019-.020 of an inch before encountering whatever lug it is contacting.

[John]

Take the slide off the pistol and turn it upside down. Put the barrel in it, with the bushing and push it up so that it locks in the slide lugs. Then move the barrel back and forth while maintaining lugs contact. How much movement do you get?

[bushka]

interesting post,according to Kvol2.,what that gap [dwell] measures matters most when an [loaded /dummy] is chambered ,because it pushes the barrel forward closer to the slide,and yet can still be a .01 to .015" gap in mil-grade gun.
take those calipers and measure some thickness of something to use as a shim gage in there.your numbers dont look bad,just maxed.
I would put fingernail polish over the bbl lugs and fire a few magazines to see whats going on with the lug bearing.

[uglygun]

Take the slide off the pistol and turn it upside down. Put the barrel in it, with the bushing and push it up so that it locks in the slide lugs. Then move the barrel back and forth while maintaining lugs contact. How much movement do you get?

I went to do as you suggest but before disassembly I did something I haven't done yet. I took a reading from the top of the slide to the top of the barrel for a reference point, then with slide removed and barrel installed with bushing I pushed the barrel upwards into the slide and took a new reading. There was a difference of .020 between readings, with the slide removed and pushing the barrel against the lugs the reading is a smaller .125 of an inch while when it's installed on the gun it's a larger .145 inch. Suggesting to me there is less lug engagement with the barrel/slide installed on the gun.


But to answer your question, measuring from the back of the barrel feet to the front of the slide I come up with measurements of 4.471 and 4.485. So it's a slightly smaller .014 inches of play.


Not sure how a new barrel link would effect things or if it would even be preferable after reading the relationship between slide stop and lower radius of the lug/feet of the barrel.

[uglygun]

interesting post,according to Kvol2.,what that gap [dwell] measures matters most when an [loaded /dummy] is chambered ,because it pushes the barrel forward closer to the slide,and yet can still be a .01 to .015" gap in mil-grade gun.
take those calipers and measure some thickness of something to use as a shim gage in there.your numbers dont look bad,just maxed.
I would put fingernail polish over the bbl lugs and fire a few magazines to see whats going on with the lug bearing.

I think I understand where you are coming from with this, however a round in the chamber doesn't appear to make a difference as the hood of the barrel is still contacting the breech face.

I loaded a dummy round to see if it makes any difference and it doesn't appear to draw the slide any more rearwards towards the lug. In order for that to happen I'm fairly sure the barrel would either need to be short chambered or have a round outside recommended OAL case length to stick out past the barrel hood.

To close the gap it appears around .012-.013 inches is needed. A piece of small dense paper measuring .017 inches crushes to .013 inches when put on the barrel hood and crushed between it and the slide(not dropping the slide from full lock, only retracting it about 1/2 inch then releasing it). Still unknown what the extent of lock up is on the first lug and other lugs though.

May wind up giving the finger nail polish idea a try.

[pa_guns]

Hi

If you want to do the engagement measurement, use a little bit of plastic clay. It works very well and will give you a fairly exact measurement.

Bob

[uglygun]

Hi

If you want to do the engagement measurement, use a little bit of plastic clay. It works very well and will give you a fairly exact measurement.

Bob

I was thinking about something like that after seeing the plastic thread they use for measuring the gap on engine bearings after the main caps are torqued to spec.

Just don't have anything like that to do it yet and it will be a few days till I can track it down.

[pa_guns]

Hi

In a pinch just about anything gooey will work. Soft candle wax probably will do the trick.

Bob

[John]

First, if the first lug is not locking, then one of the other two is. Second, the play you measured with the slide off the frame is about normal. Third, a link is not the recommended method to increase vertical locking. The barrel is NOT supposed to use the link to push it up in the slide, that's done by the barrel legs going over the slide stop shaft. The link's role is only to unlock the barrel (move it downwards, to unlock it from the slide).

[niemi24s]

What was said about the link in Post # 20 is true for a gun fitted with a "national match" type barrel with enough extra metal in the feet.

However, a mil-spec USGI 1911 does not have a national match barrel, but has a USGI mil-spec barrel. These barrels have no extra metal in the feet. With no link installed, a mid-spec, mil-spec USGI M1911 will have: about 0.042 inch of vertical engagement/overlap on the first lug; the feet will (of course) rest on the slidestop pin; there will be about 0.087 inch clearance between the barrel link pin and slidestop pin.

But, a mid-spec standard 278 link has a 0.097 inch web between its holes. When installed, this link will lift the barrel's feet up off the slidestop pin (to accomodate the the 0.097" web) by about 0.006 inch vertically.

I think Uglygun's 1911 is a mil-spec model. If so, and it happens to be in the center of the tolerance bands printed on the U.S. Army, Rock Island Arsenal blueprints: the barrel feet will 0.006 inch above the slidestop pin; it'll have about 0.048 inch of vertical engagement/overlap at the first lug; it'll have about 0.012 inch of vertical slop between the barrel and the slide.

There are only three possible ways to get this gun's (or any mid-spec, mil-spec gun's) barrel feet to rest on the slide stop pin in battery: a shorter link; a grossly oversized slidestop pin; a new barrel with more metal in the feet.

All these dimensions are based on what's in the blueprints. I've no idea what any of the actual dimensions on this gun really are - I don't have it here.

P.S. To avoid the deluge of posts about why a short link or really fat slidestop pin are dumb ideas, I hereby advocate a new barrel with more "feet meat" - but then it wouldn't be a mil-spec model, would it? Regards

[John]

I still am not sure what the problem is with this pistol or what we are discussing here.

[vikz]

john me too i'm so confused what the real problem is.. :D :confused: :confused: :confused:

[vikz]

i always try to make life simple, buy a gun,clean it,shoot it...and then clean it and shoot some more.. :lm:

[Iron bottom]

I believe he is talking about end shake.

[ArmscorBA]

I believe I spoke with him today. What he is talking about is the specs on the top lugs. The first lug is loose about 15 K. I recommended that he shoot it and re assess the lugs.
Thanks
Ivan

[uglygun]

I believe I spoke with him today. What he is talking about is the specs on the top lugs. The first lug is loose about 15 K. I recommended that he shoot it and re assess the lugs.
Thanks
Ivan

Aye, you did talk to me.

I will head out this weekend to shoot it though it will probably only be able to put 200 rounds or so through it.

During my lunch break today I went by another store to check out an RIA/Armscor 1911A1 and a Springfield USGI they had sitting next to eachother.

Both those guns exhibit some of what I was trying to describe having seen in my own gun though to a lesser degree.


Will keep you advised.