As some of you know, I acquired a pair of Norincos to call my own a while back. One had some mileage and one was pretty much ANIB. Both are pretty typical of the average Norinco... A bit rough around the edges, but completely serviceable. One had a sear that I wasn't comfortable with, so I replaced that right off the bat. Both guns were dead reliable and gave what I consider to be acceptable UTYAIA accuracy... in the neighborhood of fist-sized groups at 25 yards from the bags with good ammo... though dispersion got wider as ammunition quality fell off. An old lot of 230 Hydra-Shok produced the best groups thus far. Okay...but nothin' to write home about. While I'm not overly concerned with ragged, one-holers from a "Boondocks Pistol" I do like to see a bit better results if it's doable without sacrificing reliability. Headspacing on typical Norincos tends to be a bit more than I like, and fore/aft play within the slide runs to as much as .010 inch... which accelerates wear and battering of the lugs when the gun is fired due to slap-seating repeatedly.
So... I decided to upgrade the guns as easily as possible without getting wrapped up in hard fitting a match-grade barrel. Time is at a premium these days for me... so I opted to go with Springfield's excellent stainless drop-in "service" barrels. I discovered some time back that these barrels (Part number PI3501) were a near-perfect drop-in fit for not only Springfield ordnance-spec guns, but Colts as well, including genuine USGI pistols that had long ago lost any collectibility. Lockup was tight and horizontal play in the slide was minimal. Headspacing in these guns has been acceptable, if a litle more than I like to see. They wouldn't go to battery on a NO GO, but usually would on my homemade .910 "Field" gauge. Okay, but...
I ordered a pair of the barrels... 85 bucks a copy plus shipping. They come with a correct link, and have nicely done throats and crowns, though most are a little sharp at the top of the throat and require lightly breaking the corners. They're capable of producing very good accuracy with lead and jacketed bullets without reliability issues... or at least nothing that a little tweak can't resolve quickly.
When I went to install them for the cursory timing and initial function check... they wouldn't enter the slide on either gun. The hood was too long.
A quick-check with the caliper revealed that they came with a slightly longer hood than specs called for... and the GO gauge sat below flush with the hood face by .012 inch average for the two. The width was also slightly wider than the average factory barrel, and the clearance in both guns was fairly tight... for a drop-in barrel mated with a rough Norinco slide. The clearance was about .002 inch per side.
I had a few of MGW's excellent drop-in bushings on hand, and they were so tight in the slide bores that they had to be lapped in order to get'em to turn.
The barrels also have a slightly larger than typical flare at the muzzle, and had .001-inch clearance between barrel OD and bushing ID, and the bushings had to be clearanced a little to allow free link-down, though there was no springing evident when pressed into the slide.
I filed the hood to fit within the slide to the point of just allowing vertical lockup, and set my typical (initial) hood to breechface clearance so that the gun would just barely allow the slide to go to battery on the barrel. At this point, the working headspace was checked with the .898 GO gauge, and a .003 feeler gauge between the GO gauge and breechface wouldn't quite allow the guns to go into battery without some force. I'd judge the working headspace to be dead on at .900 inch... Perfect... and there was no discernible horizontal barrel play in the slide with the gauge removed.
Marking the locking lugs showed that all the lugs' thrust faces were engaging to some degree, and I decided to see if they would equalize with some low-end proof rounds.
I assembled 10 rounds with 250-grain SWCs loaded to about 850 fps, and fired one round at a time, checking with feeler gauges on the GO gauge after each round. Both guns equalized the lug engagement after three or four rounds to allow the return to battery easily without forcing. A check with the shims allowed the guns to go into battery on a .001 gauge with a little force... but not on the .002 gauge. An additional 50 rounds of hardball equivalent per gun was fired, and the clearances rechecked. Nothing had changed, and the lugs were fully equalized and bearing their share of the thrust load.
The guns were cleaned and three 5-shot groups were fired from the bags at 25 yards... throwing away the first shot to eliminate the flyer. The difference was astounding. Both guns shot groups with PMC ball that were hovering just above the 2-inch mark... or about twice as good as they previously did with Hydra-Shok. (4.5 inch average) Interestingly enough, Hydra-Shok didn't better the PMC groups by a lot, coming in at a tick under 2 inches. Re-testing to allow the first shot flyer didn't make a lot of difference, with the flyer opening the groups up only a quarter-inch on average with both types of ammo... and always high.
This little discovery has been evident in three different Norincos with a fairly wide space between serial numbers... though only two have been test- fired. The third belongs to one of the forum moderators, and as soon as I get a go-ahead from him, I'll order another barrel and see if the results are the same. If they are, I plan to call back a dozen or so of the Norincos that I've checked out and see if another virgin Springfield barrel fits the slides in like fashion... or won't without light fitting, as the case may be.
So, keep your fingers crossed Norinco fans... This may prove to be the hot fix for a pistol with a sloppy barrel fit and mediocre accuracy... AND... one that can be done with a smooth mill file, a gauge set, and a set of small automotive feeler gauges.
Don't forget the headspace guages John.
Just thought you may want to clarify your last sentence
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one that can be done with a smooth mill file and a set of small automotive
feeler gauges.
You know, for the safety of the children.
Ahhhh... I see now. Sometimes I get in a rush... but you're correct sir. I will edit it so that it'll be clear for all to see.
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Ahhhh... I see now. Sometimes I get in a rush... but you're correct sir. I
will edit it so that it'll be clear for all to see.
Great, I sure would hate to see this get all blown up out of proportion for no good reason, start a never ending debate and cause an entire thread to be stickied about it, that would be just wrong.
Bill... mah fren... I'm sure you can try to understand that I've got a lot goin' on here right now, and I'm tryin' to keep track of the forum too. My 83 year-old stepfather walked in just as I was finishing up that post, and why he elected to drive all the way up here alone was a concern to me at that minute.
Now... if you're tryin' to pick a fight over Dave's banning, please don't. I had nothing to do with it, and it wasn't my call. I was out for the day. I appreciate your calling my attention to something that I missed because it is an important point... but beyond that, the barbs and snide remarks from that corner are getting to be a real bore.
By now, everyone here knows that I use headspace gauges not only to fit barrels, but for routine checks on any unknown pistol that I put my hands on. It's one of the first things that I do whenever I examine one.
Another point that I neglected to post was that the barrels not only had a tight vertical lockup... the firing pins hit the primers dead center. While I don't expect that this ideal will be noted with all barrels and all Norinco slides... it shows promise, and I hope to be able to call a few back in that the owners were good enough to let me look at over the last several months.
I've got two more barrels on the way, and will report as I get more data. This could turn out to be the kitchen-table tinkerer's easier E-Z Fit barrel.
I have hopes.
FWIW... Anybody who wants a gauge set, and can't justify the cost for one or two jobs can have a set made at any community college with a machine shop... probably for free. All you need are the specs and about a quarter's worth of cold-rolled steel. They'll hold up well enough for several jobs... just keep an eye on the overall lengths. The students in these programs are usually anxious for machine time and it may earn them a few extra points on their final scores. I made my .910 "Field Gauge" in about 10 minutes on a lathe, and hardened the skin with a propane torch and Kasenit.
Tuner- glad you're back! I'm a little confused by the fact that the SA drop in barrels aren't. I was planning on getting one for my SA GI, but I can't figure why the hoods would be oversized. If I wanted the possible fitting work I would get one from ED Brown, Wilson or Storm Lake.
I may be out of my head,but assuming I could only have one 1911 and had to keep it the rest of my life,can't sell or trade.
I would rather have a good Norinco that had been Tunerized than any other 1911 on the market including all the custom ones!
Good materials,fitted the proper way, beats all the BLING in the world.
That's the thing about it... Springfield's drop-in barrels only need light fitting on the hood length... in the Norinco slides... and they do drop right into Colt, Springfeld, and *most* USGI slides that I've tried'em in, including a couple of cast Essex slides. It was the Norincos that they had to be fitted to, and it was a 30-minute job as opposed to the time involved in a hard-fit barrel or even a Kart EZ-Fit. Got my fingers crossed that it works out the same in as many Norinco slides as I can check over the next few weeks. I've got a lotta phone calls to make in the meantime. Maybe I can get a dozen or so looked at soon.
LOL Ken. I appreciate it... but you haven't had your hands on a Yost 1911 yet. I handled an Ithaca that he did several years ago... and as much as I wanted to strangle him for blingin' up a USGI warhorse, I had to admit that it was beautiful... and as slick as a spoonfulla of goose grease on an icicle.
Hi Tuner. The Norinco upgrade seems to be both cost and time efficient. Based upon your experience, would a tighter bushing fitted to the Norinco slide and barrel, and/or maybe a bit more link help accuracy as much as the Springfield barrel? In your experienced estimation would fitting a Kart EZ fit barrel or a Nowlin standard non-ramp pre-fit barrel be considerably more time consuming than fitting the Springfield barrel? And again in your experienced estimation, would the resulting accuracy be significantly improved over the Springfield fix?
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I assembled 10 rounds with 250-grain SWCs loaded to about 850 FPS
Heck, I'm still tryin' to figure out if Tuner is squeezin' Long Colt into this barrel or if this is a Tuner Testing Turbo load.
2XS wanted to know:
Based upon your experience, would a tighter bushing fitted to the Norinco
slide and barrel, and/or maybe a bit more link help accuracy as much as the
Springfield barrel?
The problem with a tighter bushing and the stock Norinco barrel is that the barrels are the same diameter from muzzle to lug instead of the slightly smaller diameter behind the muzzle that we're used to seeing on other barrels.
That diameter reduction is necessary for linkdown clearance and without it, the barrel may not go completely to bed, or... in some instances... it may not fully unlock from the slide. The hard chrome prevents reducing the diameter in a lathe with a barrel fixture, since conventional tooling won't even scratch it... making it necessary to set up an OD grinding attachment on the lathe.
That's a lot of trouble and expense to go through for a barrel that either has excessive headspace... or right on the line... and a lot of horizontal play when it's in battery and a 64th + inch of clearance between the hood and breechface. You'd have to create the clearance in the bushing... which defeats the whole purpose of a fitted bushing.
An EZ-Fit barrel would probably enhance the accuracy a little over the Springfield barrel... but probably not a lot, because it essentially accomplishes the same thing. and any further enhancement would come from the closer hood fit at the sides. A hard-fit, match-grade barrel... correctly fitted... would be the ultimate, but would be both costly and time consuming.
LOL Kruzr... That load is done with a Speer swaged 250-grain SWC and Unique and is my boondocks/camping carry load. We have a big ol' black bear wander through from time to time. Most of'em are just as anxious to stay away from us as we are from them... but once in a while we get a bold one.
My camp gun is a M-58 loaded with hard 240-grain SWCs... but that thing is too heavy for my old back when I take a long nature hike. Plus, when I'm on state park property, it's a lot harder to hide than Old Slabsides, and since the park service has decided that guns are bad things... and I've decided to be a scofflaw in bear and cougar country and to hell with the rules...
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An EZ-Fit barrel would probably enhance the accuracy a little over the
Springfield barrel... but probably not a lot, because it essentially
accomplishes the same thing. and any further enhancement would come from the
closer hood fit at the sides. A hard-fit, match-grade barrel... correctly
fitted... would be the ultimate, but would be both costly and time
consuming.
Need to get Conrad or Fred to send you the phamplet on the Easy Fit Barrel and Bushing. I still wish there was a better name for it than that, but there is a lot more to that barrel than most people realize. It's a lot more than the hood sides, it actually has pads that will fit into the upper locking lugs giving you three points at the back, feet and two pads, for fit and stability, plus the bushing is alreaady fitted to the barrel properly. You still have to do your part in fitting. The key word in the Easy Fit name is still 'fit.' I've got a few extra books sitting around I can mail one to you if you like. It's a totally different system that if you have never seen/installed one, or at the very least read the book, it's an unfair statement. Not trying to be contentuious, just thourough. Kart has come up with one hell of a system here that really deserves a better day in 'court' than most people give it credit for, it's just that name, Easy Fit, that betrays it. Oh, and that 'about one hour' claim to install it, uh-uh, not me, couldn't even get close to it, but I'm kind of picky.
Do I think a match barrel professionally/correctly installed is better? Well, the jury is out on that one with me, but right now I would edge that way, but as far as compared to a drop-in of any sorts, without a doubt.
Could the shooter tell the difference? Well, that depends on how good the shooter and his ammo are.
Bill, I've heard so many good reports on those barrels from several corners, that I think I'm gonna have a go at one soon. There's a possible project in the works, and it might fit the game plan nicely.
Without knowing for sure... having never seen one... The hood has to be filed to fit on the length and width, and occasionally there's a need for some cutting or lapping of the lower lug feet if the barrel doesn't center correctly after the pad is fit. You mentioned that light finish reaming was needed for the leade. Those aspects wouldn't put it too far removed from a hard-fit barrel that comes with a semi-finished chamber and oversized upper and lower lugs, and an oversized hood. Pretty close to the same work... just less of it.
I'm definitely interested in havin' a look as soon as the opportunity offers itself... Just waitin' for the word to proceed.
The lower lugs don't need to be touched, so there is no need for a lug cutter or file there. You do completely fit the hood, but the key is a couple of pads between the upper rear lugs, one on either side, that need to be fitted. It's really hard to explain without the barrel or book in hand. The bushing is also fit to the barrel, it just needs to be fit to the slide itself. Link/pin included and are part of the system. Call Conrad up and see if he'll send a book 910-754-5212 if you don't want me to do it, you'll see it's a far cry from what most people are expecting.
I've gotten a report on two that did need light fitting after bringing the frame rails down. The guy said that he had to take a light cut... no more than a finishing cut... after the pads had been fitted to center the barrel in the slide after the swaging operation. (I even ran into that once using a new in paper GI barrel during a salvage/rebuild on an old Ithaca.) He's into restoring worn-out old warhorses like I do... so I figure that there's probably at least an even chance that's what I'll run into since that's going to be part of the rebuild. I rarely work with new frames and slides, so sometimes things gotta be juggled to make'em work.
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I've gotten a report on two that did need light fitting after bringing the
frame rails down.
If that be the case, go for a gunsmith fit barrel. The only reason he would have to cut the lugs is to bring the center hit on the FP down since swaging the rails doesn't affect the lower demensions, i.e. SS pin, which everything else is measured against and barrel bed/vertical impact surface. If there was a lot necessary to locate the FP hit, then more than a 'finishing' cut, whatever measurement that might be, would be necessary, and this would ruin the whole concept/system the barrel was designed for. He would have had to change the link also. The better option would have been a GS fit with the proper link determined after the lugs were cut. Now, some smiths, two I know of in particular, do put 'pins' in the lugs to create the same effect as the pads, but that's not a real mainstream method and one I wouldn't use or recommend.
Now, using the Easy Fit with the pads would really preclude having to swage the rails down anyways. Sure, the frame and slide might have a little play, but when this system is in battery you have the pads fitted putting a solid lock between the two points in the top of the slide and the one point at the lugs. 95% of your accuracy in slide mounted sights is the barrel and slide fit, and this system carries it a little further. A gun that's so loose a great deal of swaging is necessary wouldn't be a good candidate for frame mounted optics, not out of my shop anyways.
EZ Fit System
Roger that Bill... I understand the concept behind the system, but the guy told me that after the swage-down... and after he got the firing pin centered, that the vertical stacking put the lower lug into a light bind with the crosspin ane kept the gun from going to battery by a tiny amount.
Match-type fits generally require light thumb pressure to push the slide the last bit... and is considered to be a good fit... but he said that it was tighter than that... and he wasn't after a full match fit anyway... so he relieved the lower lug a little from where the tight spot started all the way into battery.
The interference wasn't much, and he didn't use a lug cutter. The adjustment was obtained with a 3/16ths drill rod and 600-grit lapping compound with the slide under a load from the recoil spring... turned by hand. The link required a little massaging to get the crosspin back into contact with the lugs so that the barrel wouldn't stand on it in vertical lockup, and to regain full contact across both sides of the lug and the link.
The disconnect slot in the slide also had to be deepened slightly due to the lowering of the rails and slide. Such things are pretty commonplace when salvaging worn frames and slides. Makes a different approach sometimes necessary when not starting from scratch with new, in-spec frames and slides. Such are the headaches that I've had to deal with, since I usually work with old USGI and well-worn commercial Colts, etc. Each one becomes a law unto itself.
He also said that one gun required a little work at the barrel bed in the frame bridge to let the barrel fall low enough to allow the slide to pass over the top without hitting the locking lugs. Another operation that I've had to do on occasion, sometimes requiring so much that I took part from the lower radius of the barrel and part from the frame.
I ran into much the same situation last year when I tightened up the slide to frame fit on a nearly new NRM Colt Government Model with the factory barrel. It removed all the vertical play at the rear of the barrel and since the link was the correct length, no adjustment was needed on that. A fitted bushing capped it off, and the accuracy was improved quite a bit.
I fully intend to give the Kart EZ-Fit a try on a future project... Already got it in the planning stages... and I'll do a report on it when it's finished.
I work with old stuff too John, we all do. He would have been better off polishing the hood of that barrel down a little instead of altering the lugs and the barrel bed. The hoods on these barrels don't come polished anyways, and even on a new frame and slide it is necessary to polish the hoods all the way around. This would have kept the lower in spec and the barrel in spec and sounds like it would have had just the slightest off center hit which really isn't that big of a deal. I guess it's six of one and half dozen of the other, but I'm betting that his hood is still in the rough like it was sent from Shallotte, NC in the first place.
The point I'm trying to make is that the barrel is designed from the lower lugs up. The lower lugs carry the load at the top radius and lower tip of the lugs with a free space in the arc of the lugs. This gives a wedge lock on the pin that is always repeatable. Lapping this area in too much or altering the link will give the barrel an opportunity to lock up anywhere in the arc and at varying degrees. Now we are only talking thousanths here, but that relates to half an inch at 50 yards, per .001 of difference, of mechanical accuracy this one action alone eliminated, or possibly eliminated. How many times have we both agreed that .001 is the difference between right and wrong in a lot of instances, or that it looks like a mile long?
If all of the alterations your buddy had to make were necessary for everything to work he could have saved about 50.00 on the barrel and another 40.00 on the installation kit and went with a gunsmith fit barrel. If he would have left them alone and just polished the hood down that 'finishing cut' amount instead of altering the frame, lugs and link, he would have recieved the full potential out of the barrel and not taken a chance of altering the linkdown timing by putting an eccentric round on the link, besides, it would have been a lot easier to do a little shoe shining then all of the hassel he went through. Actually, depending on the amount of play, he could have avoided the entire swaging process that will eventually loosen up anyways.
Bill Z said:
but I'm betting that his hood is still in the rough like it was sent from
Shallotte, NC in the first place.
Howdy Bill... You'd lose that bet. This wasn't exactly his first trip to the county fair.
I understand perfectly what you're saying. He'd much prefer to work with a "Hard Fit" barrel too... but he got a deal on the pair and had a project in the works for his two grandsons, and figured "What the hell." I spent nearly an hour on the phone with him... on my dime... listening to him describe the virtues of the Kart system as opposed to the virtues of the Scheumann hard-fit barrels. He likes the system, but says that it does have a few drawbacks when working with worn, salvaged pistols.
Getting the firing pin hit centered is a big deal for him, and once that was done... the only option that he had open was to go to the lower lug, since he had already gone to a .195 diameter slidestop pin. He wouldn't remove any more of the hood and tops of the locking lugs than necessary to clean'em up because he believes in as much veritcal lug engagement as he can get, especially on that first lug at the front of the hood. So do I, because that's the main one. Unless a full hard fit barrel is used... complete with oversized hood and short, semi-finished chamber... often the two forward lugs don't hit at all, and cutting back on the first lug sometimes still only allows for one more, and increases headspace by the amount of adjustment on the first lug. Once in a while, you get lucky and get them to equalize... but with a low-pressure round like the .45 ACP, it's not really that critical for the lugs to equalize.
Anyway... He only ran into the problem with one of the pistols. The other one worked out just fine. It was just a matter of how the tolerances stacked up after the swage-down. Like I said... I'm gonna try one of the Kart barrels for an upcoming project. I'll know more about how it works at that time.
Meanwhile... I've got a third Norinco (with a BAD headspace problem) on the bench and two more Springfield barrels on the way. I'll check both and see how things look when they come in. Hopefully, I'll have another half-dozen pistols lined up to check against the barrels byt then too... This does look promising for those who have Norincos with sloppy barrel fit or bad headspace and don't want to go the full route to upgrade their guns and make them safe and happy.
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I understand perfectly what you're saying. He'd much prefer to work with a
"Hard Fit" barrel too... but he got a deal on the pair and had a project in
the works for his two grandsons, and figured "What the hell."
The Kart Easy Fit is hard fit, more so than a gunsmith fit and for the little you are talking he removed, it would be impercievable on the FP hit and polishing the hood a little more would have cured the woes, unless of course he took more off of the lugs than he is admitting too. I still wouldn'y cut an eccentric in the link either way, and then replacing it is just like installing a GS fit, but then he would need the correct link, if he knew how to determine it, so that was just extra value/money spent/wasted. His dollars, not mine.
Both of you are missing the entire point of the Kart system. I'm sure you will be enlightened when you finally get around to ordering one and reading the manual, I seem not be able to get my point across, but I blame that on Fred calling it an Easy Fit and not coming up with a better name for it, but I cannot think of one either, oh well. Hopefully the preconcieved perceptions of this barrel will disappear in time and people will understand it's function before they keep assuming what it is. BTW, the quality and materials of the barrels is the same, they are both NM barrels, it's the lock-up and fitting part that is different and the bushing is correct for the barrel to boot. You'll see.
So these barrels would be considered true drop in for SA production models?
I have one 1911 and is my only handgun so I plan to get a few spare parts. One barrel and one extractor and so forth.
I would get those parts from SA that would fit drop in and fix all that do not.
txgho1911 asked:
So these barrels would be considered true drop in for SA production
models?
Now that's the 64-dollar question. While a Springfield barrel... or one made to Springfield's set of specs... would afford the best CHANCE of a simple, drop-in fit, it's best not to count on it. Years ago, it was a government requirement for the guns from all contractors to provide complete interchangeability of parts, but since the guns aren't destined for life and death in faraway places any more... there's really no such thing as the promise of a drop-in fit on anything.
The situation that I stumbled on with the Norincos may simply be a stroke of good fortune on those particular barrels and those particular guns... and they did require some light fitting. Both barrels that worked nicely in the two pistols also seemed to bear out in a third gun that I don't own. I've got two more on the way, and I plan to try them in a few Norincos that belong to several friends... just to see if it was a fluke, or if it's a common occurence.
Time will tell.
I do know that those same barrels didn't have the overlength hood just three years ago... and that they did drop into a pair of old GI Colts and work pretty well, though there was also a little fitting required... it was very little.
Headspace was well within spec for both guns, and they've both done hard range duty ever since, with over 30,000 rounds logged between the pair before the slides cracked. I replaced them with Essex castings... with the same results as with the original slides. After fitting the Essex slides with new bushings, the barrels were drop-in and go. Another 20,000 or so rounds and they're still on the line... though they're starting to loosen up a bit.
I will have to agree with Bill the Kart "easy fit" is not for the faint of heart nor will an hour install one.
The more I hear about those barrels, the more anxious I am to try one. I'm curious as to how readily the lugs will equalize horizontally, and how much finishing the chambers need... I'll probably have the opportunity to do one early this coming summer. Still waitin' for word to start.
Update:
Two more barrels arrived the other day. They both checked out pretty closely to the same way that the first two did in the same two Norincos.
Two more pistols that were brought in for the check produced the same results. A fifth one didn't. There were a few issues with the slide dimensions that required more work to get one of the barrels installed correctly, and I could only get two of the lugs to engage horizontally after setting the load- bearing face of the first lug back .005 inch and firing the gun 50 times. The lug locations on all 4 barrels were within .002 inch of each other... so the issue was in the slide itself. In all others, the lugs equalized nicely.
Vertical lockup produced a lot of interference in that one gun... much more than in any of the others... requiring more material removal in the slots between the barrel lugs. Once the barrel centered in the slide, a little scraping and lapping of the lower lug was needed to relieve the remaining tightness. in vertical lockup.
This pistol also required .003 inch of reduction on the bottom radius of the barrel behind the lug in order to obtain correct linkdown clearance with the slide... and to keep the barrel from stopping hard on the frame bridge and stretching the link, I removed an additional small amount from the frame bridge itself. Also, the #1 lug required light dressing in order to obtain clearance for the slide. There was no hard contact with the corner, but there was light contact along the top of the lug. Likely would have worn in with use, but it was dressed lightly with a smooth mill file and polished with emery cloth via the "Shoe Shine" method anyway.
Total headspace for the barrel in this particular gun is a bit more than I like, but still within acceptable ordnance specs at .008 inch above minimum as measured with a GO gauge and feeler gauges... for a total breechface to stop shoulder dimension of .906 inch, with .002 inch clearance between the slide and hood as measured with shim stock.
I expect that additional firing will allow a little more horizontal equalization between the #1 and 2 lugs, which may allow light contact on #3. This will likely produce a total hood to slide clearance of around .005 inch, which is also acceptable in an ordnance-spec, service grade pistol, and MUCH better than the OEM barrel fit... which had excessive headspace and unacceptable fore/aft play within the slide.
So far... the Springfield/Norinco match seems to stand at an 80% chance of a quick and easy upgrade. I'll know more as more pistols come in for examination. 4 of the owners contacted have ordered the barrels for the upgrade on their guns, which will provide more in-depth information as they are installed and fitted.
On an additional note... The barrels come from Springfield with slightly raised material in the slots between the lugs. The slots, rather than being machined flat and square with the lugs, are slightly raised in the middle, which seems to work a little like the Kart EZ-Fit system. Not sure whether this is intentional and specifically FOR that purpose, or if it was the result of the EDM machining process... but it works well. Note that the Hammer Squaring file with two safe sides from Brownells fits between the slots, and is perfect for the job. The safe sides allow the slots to be cut deeper without removing material from the lug faces, and vice versa.
That's all for now. I'll report more as I learn more.
The Norinco barrel issues seem to be fairly hit and miss, but not rare by any stretch. Near as I can determine...a bout 1 in 10 could stand a new barrel.
The Springfield service barrels worked out nicely, but weren't drop-in. They needed light fitting in the Norincos that I used'em in. The Kart EZ-Fit would have been better overall, but the Springer tubes were almost 50 bucks a copy cheaper, and yielded completely satisfactory results with complete feed reliability with little tweakin' involved, and accuracy on a par with the average Gold Cup. Not match-grade, but good enough to bounce oil cans at 50 yards if I don't drink that third cuppa Turbocoffee before headin' for the range.
My goal wasn't accuracy so much as it was a slop-free fit and a little tighter headspace. The ones that were OEM were very close to SAAMI maximum at .918 inch... well past my self-imposed max of .910 for a hard-use shooter... so I decided to rebarrel the guns and put'em to work.
Johnny, hoping the sights will fit the Norinco pretty well. Got them from Brownell's with rear dovetail supposed to fit "Colt" with front being a narrow tenon... which I think is what the Norinco is.