Just wondering if its possible to silver solder steel shimstock to the sides of the under-barrel lug frame slot to tighten barrel lug to frame fit. I happen to have a frame that is about 0.010 wider than the barrel under-lugs... just wondering if I can tighten it up without having to have the frame rewelded and machined.
On the other hand, if I didn't mind a less accurate gun, would there be any problem with 0.010 of play in this area?
Is the receiver or the barrel more expensive? Change or modify the cheaper part.
Why do you want to tighten the lug to frame fit? It's a clearance that allows the barrel to fall to bed when the gun is out of battery.
Got nothin' to do with accuracy.
Have you measured the barrel lug width?
FWIW, the derived spec for a U.S.G.I. M1911A1's clearance in this area is 0.0075 +/- 0.0045 inch.
The shim stock idea might work to tighten it up, but I think the biggest problem would be getting the shims to leave an equal clearance on both sides. In battery, the lower lugs on your gun may not be centered in the slot. If the gun locks up tight in battery a shim that would tend to move the lugs sideways from their normal position might create additional problems - like only one lug foot contacting the slide stop pin.
Not even sure reducing this clearance successfully would have any measurable effect on the gun's accuracy. Barrels are cheaper than frames, and it probably wouldn't hurt to try - the shims could always be removed if they didn't do any good.
Remember, though, that your 0.010 inch of clearace is only 0.0025 inch above the mid-spec value.
I think you could do it, and such trickery was once a standard way of taking out clearances in accurizing the pistols.
Play it safe with lead solder - lower temperature, less permanency.
Be sure to do equal shimming to each side of the slot or you could make lopsided slidestop contact and/or off center top lug contact in the hood notch of the slide.
Or leave it alone and count your blessings that the pistol functions without a hitch. From tightening the frame notch side clearance you may or may not realize an improvement of accuracy. There are several other factors playing a part in the pistol accuracy, and there is "one man's accuracy is another man's Chevrolet," or somethin' like that.
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Why do you want to tighten the lug to frame fit? It's a clearance that
allows the barrel to fall to bed when the gun is out of battery.
Whassat? That place don't have to do with the rotational barrel chacha when it's crammed up ready to fire? OMG!
I was reading an article about Bullseye modifications to accurize pistols. I guess it sparked my imagination... ;-) Hill is probably right in thinking it had been done before. I guess since the parts are still within tolerance, I'll probably not attempt it. I have soldered hilts onto knife blades, and some other tricky soldering when I was crafting jewelry (silver soldered silver sheet stock using paste solder), also soldered for plumbing, brazed and even welded cast iron. So this seemed like something I could do... I think I will refrain, since It would be a major headache to fix if I screwed it up!
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Whassat? That place don't have to do with the rotational barrel chacha when
it's crammed up ready to fire? OMG!
Why do I think it is the barrel hood extension that has more to do with the rotational positioning of the barrel, than the area AK625 is talking about?
I do this all the time on loose frames.
It is definately necessary for fine accuracy on 50 yd. bullseye guns. It is the reason a properly fitted ramped barrel will many times out perform a standard barrel for fine accuracy. The added support gained by the precision fit more readily transfers the barrel torgue to the frame and prevents the lower lugs from trying to lift off the cross pin under torque.
I tig weld the lower lug sides and surface grind them to the desired clearance.
You are on the right track...
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The added support gained by the precision fit more readily transfers the
barrel torgue to the frame and prevents the lower lugs from trying to lift off
the cross pin under torque.
Hmmmmm... Never had thought about this. Interesting!
Still thinking... Hmmmmm.
I was considering soldering some kind of shim stock, or thin carbon steel razor blade material in place, since I can't tig weld... and I was thinking of working on the frame, since its carbon steel and the barrel is 416 stainless. I'm not sure about soldering to stainless (I've read some stuff about the alloy of the solder etc. It takes more heat, and sounds more like a brazing process). It also seems like it would be easier to solder flat stock to a flat surface, such as the barrel under-lug slot surfaces.
At this point, for me, I've decided to keep this discussion theoretical. Maybe, someday, if I have a wild hair, I might give it a try. The gun I'd be working on is an 1980's model Federal Ord. Its a horribly built, and fit, surplus-parts gun. I've already ditched the original barrel and slide, since they suffered upper lug damage, due to poor lug engagement. It was also riding the link when in battery. The lugs clashed unhappily as it went into battery, and had more fore and aft play than than I could shake a stick at. I believe I could shoot a pie plate sized group at 10 yards...
I'm planning an attempt at fitting an Armscor slide, and the 416 stainless barrel I mentioned earlier. It should be an educational project... maybe not successful. I'll probably be asking more questions as I delve deeper into the project.
Hey, I'm glad this thread has other people thinking too... It's enjoyable to read and consider other's thoughts and experiences.
When installing a Storm Lake "drop-in" barrel in a Caspian frame, I discovered that the lower lugs were quite a bit wider than the opening in the frame. It's the first time I'd found anything but a rattly fit in that particular location.
Confused...
Are you referring to the narrow slot in the very bottom of the lug's recess... or the radiused area that the lug feet drop into?
I was sure that you were thinking of that slot when you answered above.
No, not the narrow slot for the link, the side to side of what you just referred to as the "lug recess".
strange but related: I had said that the new GC has some .009" side clearance at that spot. I'm looking at my 1978 issue GC, never fired, and measure the lug recess at .356" for the barrel foot lug width of .354". Seems like Colt used to attach some importance to that fit, more than they do now.
edit:I mean by "issue" that the pistol was put on the market that year, it was new then. Not that it's any sort of military issue pistol.
BTW, and this one is totally off topic: Tuner, I put a squared FP keeper in the new GC last night and just fired for effect. Beautiful! Definitely a nicer gun with hardball ammo. I'm lefthanded too so a 1911 has always recoiled with a twist toward me, not away. Now it goes straight up.
Stupid me ordered three of them from Brownell last week 'cause they're $12. but failed to notice that there's another one in there for 80 series guns. I burned three cheap mill bits cutting the silly too big one into the 80 series shape, and spent hours practicing my fine filing skills as a result
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No, not the narrow slot for the link, the side to side of what you just
referred to as the "lug recess".
Ahh. Okay. Same page.
I thought he meant the radiused area where the barrel feet clear.
Jerry steered you right. One thing, though...
There's a limit to how tight the side clearance can be until you start to run into barrel drop problems... as in not letting it fall far enough to get clear of the slide unless the link is absolutely perfect. If there's slack in the link, and the barrel isn't linked down far enough to clear the slide...a tight fit there can keep it from dropping to bed after linkdown. If the upper lugs aren't completely clear of the slide's... even just a few thousandths... they'll be damaged, along with the lower lug by its contact with the vertical impact surface.
In other words... If you're going to close up the clearance to keep the barrel from torquing, everything else needs to be on the money... and even at that... if it's a little too tight, it can still cause some problems when the gun gets dirty. That clearance is there for just that reason. Making it tighter means keeping it cleaner.
Tightening up Browning's clearances in the effort to make a target pistol out of it essentially means building the gun out of spec. Wicked accurate they can be... but it comes at a cost, and it brings to mind an old engineering dictum:
"If you change one part of a successful design, you usually have to change three other things to compensate for it." Precision means long hours of making sure that everything is just so. Simply tightening something up without seeing to everything else that's affected is often counterproductive. Such precision means many hours of tedious work. Bullseye pistols are built for that from the ground up... not from the top down.
I'm beginning to wonder if Colt didn't change their priorities when offering us the Gold Cup or other purportedly more accurate versions of their pistols. I'm saying this because in the newer GC the barrel clearances are more or less even lug to hood where in the older version the lug is notably tighter while the hood to slide notch is .020" - .010" each side when in the pistol in battery. It's too well done to have been an accidental manufacturing coincidence, IMO.
None of it matters to me in the sense that I'm looking for a competitive pistol. I know who to call for that. It's just that I have this opportunity to compare two Colts that are the same model but thirty years apart. It interests me because I like the design, history, and use of the old girls.
Have a question about when you build one those tack-driving-at-50yards Bulleye guns with the barrel feet/frame slot clearance minimized.
Do you also fit the sides of the barrel hood for minimized clearance between the breech face guide blocks?
Been thinking a lot about using your method in a build, but suspect it would be very difficult to get simultaneous close fits at the barrel feet/frame slot and the hood/BFGB's.
Especially difficult if the slide/frame lateral fit was quite close.
Thanks 1911Tuner. Your words of wisdom are well taken. I kinda had a feeling that the soldering was just the tip of the iceberg... Thats why I decided to ask about it before launching headlong. Think first, act later if its appropriate. Its a lesson I've had to learn too many times...
I may not think highly of the Fed. Ord. 1911, but its still a 1911... I'm hoping I can make something of it without destroying it. I think I'll shoot for reliability and mechanical soundness before accuracy.