general qustion on barrel lock up???

[hutch1510]

hello, i have won a aregentine colt sistema ser 50,xxx on the auction boards, got her for like $475 shipped, has original finish and not reworked,,,says the barrel is excellent condition heres my question... i have read that pretty much all new production guns, do not lock up on all 3 lugs, but rather just the 1st lug which is strongest... while this may be true today, i would like some opinions on a argentine colt sistema made in 1949, safe to assume that all 3 lugs or atleast 2 will lock up? it has matching numbered frame slide and barrel....i pretty much bought it, because quality steel was used, is original mil spec,,, and was hoping for a gun that would truly lock up on barrel lugs as the original design was intentioned....... also on the refurb'd guns, any opinions as to whether time was taken to truly get posative lock and equalized lugs .... if these guns have good barrel lock up, that would be a real plus to know... thanks much....

[RickB]

Originally, the guns were built with (at least) one lug in longitudinal contact with the slide, then upon proof firing, the other lugs would seat via slight deformation of the slide. If everything was done right, you'd have contact on all three lugs. Today's slides are enough harder that you don't get this "pressure seating", and in .45 ACP, it's probably not critical (YMMV). Kuhnhausen's manuals indicate it is all but imperative that you have equal contact on all three lugs, if the gun is chambered in any of the higher-pressure rounds (Super, 10mm, 9x23), as the a single lug won't handle it.

[1911Tuner]

Very few production guns these days have equalized horizontal lug contact.
In the early production guns, most had at least two...and it was done by proof-firing to slightly deform the barrel lugs...not the slide lugs.

These days, not even all custom builders fit for equalized lugs unless spefically requested. Most fit to the #1 lug only, and if they happen to pick up another lug in the process, so much the better...but few fit for all three
without being asked to.

With standard-pressure and limited +p ammo, the #1 lug is sufficient, provided that there's minimal to zero fore and aft movement between barrel and slide. This eliminates the occurrence of "Slap Seating" which tends to
deform barrel AND slide lugs...Bad JuJu. With high-pressure ammo, such as
.38 Super and 9X23, equalized lugs become more critical. With such hot-rods as .45 Super, et al...it's imperative...at least if you want the gun to last longer than about a hundred rounds. Proof-seating is done with 2 or 3 rounds of proof-level ammo...which is loaded to about 25% over standard.
.45 Super exceeds that level.

These days, it's possible to pressure equalize, but the practice is more tedious
than with the old ordnance steel barrels...because the steel today is harder and deforms less readily...tending to crack or shear instead unless the amount of deformation is limited to about .002 inch or less. Less is better.
Ideally, the lug(s) that are to be pressure equalized should be in light contact in order to hold deformation seating to a bare minimum. Otherwise, it's best left to simply shooting the gun...sometimes refered to as the Break-in Period...in which everything seats more gradually. Lugs that aren't dead square to one another are covered during this period...which is often why a gun's accuracy will improve after a couple thousand rounds. Lugs that aren't engaging squarely tend to whip the barrel and slide laterally when the pressure slams'em together. This is also the reason that builders of high-end bolt-action rifles lap the locking lugs to fit in the receiver. It prevents receiver and barrel deflection when the rifle is fired and reduces lateral shot dispersion.

Understand too, that whatever lug deformation occurs...working headspace increases by a like amount.

Hope this helps...

[hutch1510]

yes it helps much.... i am tdy with the air force now, and i won (2) 1911 pistols at auction, a norinco and the argentine.... i will be back home in about 2 weeks and look forward to recieving them..... i know after reading "nork report" thank you...(1911tuner), as well as everything else i could find the "tuner" commented on and or wrote,,, i print it all out and read it about 100 times before i go to bed,,, i find myself obsessed with the 1911 now, and really dont even want my other handguns and will sell em once i get home to feed this obsession.... anyway i know i am eventually going to try to hard fit the norinco with a barrel that will have atleast 2 lugs locking, as i want to shoot it a ton..... as for the argentine, i was curious as to whether it would be atleast reasonable for me to expect atleast 2 lugs lock up.... seeing as it is "old style" armory production???

[1911Tuner]

Hutch wrote:

As for the argentine, i was curious as to whether it would be atleast reasonable for me to expect atleast 2 lugs lock up.... seeing as it is "old style" armory production???
***********************

Answer...Possibly. Though the majority of post 1911 pistols were assembled via select-fitting rather than hand-fitting, based on gauged GO and NO GO specs...and the Argentines were working with Colt equipment and blueprints...many of the A1 military pistols did indeed have more than one lug bearing/sharing the load. Of the ones that didn't do so from day one, the lug fit in the slides was usually close enough that a few thousand rounds would bring them into the game...if only lightly. If one happens to be the #1 lug...the wall without a slot behind it/closest to the chamber...Plus! #1 is the strongest and most supported lug.

Hard-fitting for two lug isn't really hard. It's when you go for all three that it can get a little tedious. If you can get #1 and either one of the others into play, you're way ahead of the pack on 98% of the production guns available today, and many of the full customs...and if you get the third one to within a thousandths or two, it'll come in time. All it takes a lotta rounds downrange. Dirty job, but somebody's gotta do it...Right? :cool:

[John]

If anyone wants to equalize your lugs in the way Johnny suggested, let me know, I'll do the ... dirty work for you, as long as you provide the ammo, food for the family, and a bedroom to sleep.

I am sure you can't resist the offer. :)

[1911Tuner]

We have a volunteer! :D

[hutch1510]

so i believe 2 lugs locking will be fine... i am going to order AGI video on the 1911, as well as eventually get the manuals 1 and 2 that is always talked about begins with a "K" anyway.... i really do plan on ordering a barrel, that can be worked for atleast 2 lug engagement... i also have a good digital camera, so maybe we can to a thread on barrel fit,,,, i'll look into getting a kart hard fit, or other that will need fitting... and take lots of high quality pic's of my progress and hopefully get some help from you guys,,, i just want to make atleast one 1911 almost perfect for my carry gun,,, i already think i'm gonna sell my SIG GSR just because it does'nt appeal to me anymore... i have always been into the older style guns, have mauser k98's and m1 garands and such... i dont like new guns they are mostly junk... i like the new norinco's though they are an exception to the rule.... anyway..look forward to posting my progress whan i get home... in the meantime i think i will research what parts to buy.

[stans]

i dont like new guns they are mostly junk
I wouldn't say new guns are mostly junk, just severely lacking in character. :D

And never assume a semi-auto has proper, good, or even acceptable lock up. Always check, you may be pleasantly surprised or you may get the fecal matter scared out of you.

[mike h. buness]

Tuner, Stans & John! Without pressue equalizing the lugs. how whould you fit a new slide/barrel with all 3 lugs in contact? Is there a way to cut the slide/barrel lugs after the hood/breach face fitting that does'nt require the break-in step? Mike.

[John]

Tuner, Stans & John! Without pressue equalizing the lugs. how whould you fit a new slide/barrel with all 3 lugs in contact? Is there a way to cut the slide/barrel lugs after the hood/breach face fitting that does'nt require the break-in step? Mike.
Take my name out of that list, I am not that experienced in these issues. Tuner or Stans should answer it.

[stans]

You will need a gunsmith fitted type barrel, not a drop in or semi-drop in job. You will also need the tools and instruments for cutting and measuring. If you are only going to fit one barrel, let a qualified gunsmith do it for you. If you plan of fitting several barrels, invest in the all the right equipment, but be warned, it is not cheap and it is not easy if you are going to do it right. I'm just a shade tree gunsmith, one step above the kitchen table gunsmiths (aka: Bubba) and I only work on my own guns.