ARMSCOR barrel in a Norinco

[batoy1911]

Been lurking around and have learned a lot from the smiths and THE mechanic in this wonderful forum.

My Norinco’s barrel lower lugs are too far forward. It failed the swinging slide stop arm test and there are no impact marks on the backside of the lug (link stopping the barrel?). I tried a longer link but started to have feed problems. It still failed the swinging arm test with the longer link (Wilson #5).

I gave up on the Nork barrel (it is soft anyway, right?) and bought a blued ARMSCOR for $50. The ARMSCOR barrel seems to fit the Nork pretty well without any smithin’. It passed the swinging slide stop arm test with the Nork bushing and link (.278). It even passed the test with a Wilson #5 link (is that possible? Or might I have done the test incorrectly?).
The gap between ramp and throat seems correct also. Barrel hood can’t be pressed down when the gun is in battery. The lower barrel lug rides the pin at the front convex radius and into the straighter portion of the lug. The pin is snug at the concave lug radius in lock-up (link hole is slightly below flush).

The gun functions smoothly and is VERY accurate - I can consistently make three holes touch each other at 7 yards. 12 rounds would go into a 3-inch group at 14 yards, consistently. But the POI is about 4 inches high of POA and it’s about an inch to the left.
Reliability with ball seems ok (not much shooting yet). I did try 100 rounds of LSWC – lots of FTF/failure to go to battery with standard 7 rounds Nork mag, CMC Power10, Novaks Mag and Cobramag. Polished the barrel ramp shiny with 1000 grit sandpaper. No improvement in feeding LSWC. All test shooting were done with the .278 link.

I measured the slide lugs and barrel lugs. Differences are (from lug 1 to 3) .009, .0098 and .019. There are shiny impact marks on lug 1. It’s corner is sharp but there’s a little shiny portion on top. After another 100 rounds some shiny impact marks are visible at the upper part of the front face of lug#2.

Barrel lug#1 measured .0386 high (short?). I did the lock-up measurement. Using .0386 lug height as the divisor, I’m getting 85% engagement at lug#1 with the Nork link. Since my lug height is shorter than the usual .050 I must strive for a deeper engagement right?

Can I go to .281 or .283 link to get a little more vertical lock-up and bring the POI down? Or is it best to ask a smith to bring the slide a little lower since I’m already getting good accuracy with the .278 link? Is there anything I can do to make my gun feed LSWC reliably?

Thanks all

 

[1911Tuner]

Engaged

If the first lug is indeed bearing the horizontal brunt of lockup, you're probably okay for standard hardball-spec ammo with .038 inch vertical,
provided that the headspace is mid-spec. I wouldn't shoot a lot of hot-rod +p ammo in it. Also, if the #2 lug is within kissin' distance...about a thou or two...it'll likely start to come into play within a couple thousand rounds, and help #1 out. Due to the barrel tilt, you won't have quite as much engagement on #2, but anything that it does give helps.

I'm fairly anal over maximum vertical and equalized engagement...but that's probably because I shoot so many rounds annually. Barrels are expensive.
Replacing one per pistol every 16-18 months just ain't my idea of a whoopin' good time.

 

[1911Tuner]

re:

Almost forgot! Although you can get the lugs a little deeper into the slide with a long link, it's best not to go that route. Usually causes more problems than it solves. Possibly expensive problems...

 

[batoy1911]

How to feed LSWC

Hi Tuner

Thank you for the quick reply. I'm not getting the entire .0386 height of barrel lug #1 to engage, just ~ 85% of that (~.032). I almost exclusively shoot reloads (~170 power factor) so I guess the barrel would make it through a few years of shooting?

What would be the consequence if I tried shooting the Nork with .281 link (Marvel +3)?

Been struggling to post some pict. 'Might be able to add them later.

The 3 Wolff SS 7-rounders with the 11# springs that I ordered direct (sold my 3 CobraMag 10-rounders to finance the purchase) came the other day (do they perform as well as the similar metalform?). Got them instead because they're cheaper and already came with the recommended spring and I can't seem to find the Metalform 7 rounder with flat dimpled follower on their website nor at Brownells. Now the Wolff mags in the configuration that you favor are also no longer available in their website, I must have been lucky enough to get their last few units . Tried some LSWC, they fed ok. 'Will try to shoot some more to test them thoroughly. I really want to make this gun work with LSWC. I also came across an [URL="http://hometown.aol.com/cargun12/mags.html"]article[/URL] 'bout the Pachmayr follower (#692-702-000) being reliable and feeding LSWC smoothly. Do you have any experience with them? They don't look dimpled but the configuration of the follower seems to achieve the same "braking" benefit that the dimple provides.

Thanks Tuner, it's an honor to be talking to you...

 

[batoy1911]

Feeding LSWC

BTW do all new production 1911 have difficulty feeding LSWC or is it just my Nork?

 

[HSMITH]

Set your seating die with a round of factory ball ammo. After that a gun that is decently set up should function with SWC ammo, if it doesn't try to get some pictures or a really good description of the failure.

My last couple guns run SWC flawlessly, but I set my seating die a LONG time ago and left it alone since.

 

[1911Tuner]

Lugs

batoy wrote:

>Thank you for the quick reply. I'm not getting the entire .0386 height of barrel lug #1 to engage, just ~ 85% of that (~.032). I almost exclusively shoot reloads (~170 power factor) so I guess the barrel would make it through a few years of shooting?<
************************

The answer is...it depends. .032 vertical is only 64% of what it should be, assuming that the first lug is bearing the brunt horizontally, it'll last longer than it would if it was engaged at 64% of just one of the others. The first lug is the strongest. The other two aren't as well supported in the rear because of the slots behind them.

If you have 64% of the first lug bearing the load AND one of the others is also taking a share, it'll last longer still...but still not to its full potential.

.032 inch is what you have on the first lug, since that's all you can measure without using other methods. The barrel tilts up into battery, which means that you'll get a little less on the second lug, and a little less than that on the third, assuming equal lug dimensions. When you get into the 60% range, you're treading on thin ice, especially if the barrel has very much fore and aft play in the slide. Of course, the lighter your ammo, the longer it'll remain serviceable.

What happens is...As the front faces of the barrel lugs start to deform, the headspace increases by the amount of deformation. Simply put...If the lugs
set back by .010 inch over the course of time, the breech will open by that amount when the gun fires because the slide and barrel are going in opposite directions until the lugs engage and lock them together. Whatever slack is there before the lugs stop the separation is the distance that the case will back out of the chamber under pressure. As the case backs out, case head support is lost.

Keep an eye on the barrel lugs for any sign of setback and flanging at the top front. Keep a close check on your fired brass. If you start to see bulges just ahead of the web area, or even feel more resistance as they're almost all the way into a sizer die...you've got a problem that...if allowed to continue...will likely cause a case rupture sooner rather than later.

 

[batoy1911]

FTF but no bulged brass

Thanks Tuner. I'll keep an eye on those lugs and those fired brass.

For now, brass don't look bulged near the base. Lug#1 has some shiny part on top just at the corner. But the lug edge is sharp to touch and looks square (no rounding off).
Barrel doesn't seem to have much fore and aft movement. With the slide and barrel/bushing off the frame, I held them in the locked position in front of the PC monitor and looked for a gap between the hood and breech face. Pushing the barrel back, the barrel hood very lightly touches the breech face. Barrel pushed forward, I could see the gap become wider but still could not insert the corner of a dollar bill thru. Since rounds are flush with the hood, my headspace is probably on the safe side?

If I used the .281 link (sorry, Tuner, I know you said it’s best not to use them long links… I just have to ask) what danger signs should I look for?

HSMITH,
I'll try to get pictures of the hang-up next range session. It's basically a failure to feed. The leading edge of the round seems to bypass the frame feed ramp, hits the barrel ramp/throat low and gets wedged on the sharp bottom part of the throat. Deep gorge mark on the lead is visible on rounds that failed to chamber. This appears to happen more frequently with the mags that have a high feed angle (CobraMag and CMC Power10). I also have Novaks mags, FTF also happen with them. The least number of failures are when I'm using the mags that came with the Nork. I just recently received Wolff 7-rounders. I'm yet to experience the hiccup with it. Not much rounds have been fired using the Wolff though.

I don't load my own ammo. I get them from a local gun store. The LSWC average 1.261 in length. I think it's the slim profile of the leading edge of the bullet that's causing the problem. I believe LRN rounds are deflected up a little by the frame feed ramp because of its rounded shape and approach the chamber at a more acute angle missing the sharp bottom edge of the throat. Never get any FTF nor any other jams with those. A buddy loaded me 100 rounds of his LSWC. All 100 went bang with no trouble. 'Buddy's SWC have a little 'fatter' nose. Hope I can get those pictures soon.…

Thanks to both you and Tuner...

 

[1911Tuner]

Headspace

Quote:

> Since rounds are flush with the hood, my headspace is probably on the safe side?<
***********

Has not one thing to do with it. You can have a dead flush condition there and still have excessive headspace...or non-flush and have good headspace. The only way to know is to gauge it.
Read the sticky at the top to understand it better.

Long-linking a barrel will increase vertical engagement, but it can also bring on other problems...sometimes expensive ones. For one thing, it delays linkdown and drop timing. That, in itself isn't necessarily a bad thing unless it's delayed enough to let the back of the lower lug hit the frame's vertical impact surface before the barrel lugs are clear of the slide's. It also very often places added stresses on the link's pin and the hole that it's pressed into. Generally, not a good idea.

 

[batoy1911]

Tuner, the flush round and the minimal fore aft barrel movement. Does it mean anything good?

I'll leave the .278 link alone and just watch the lugs...

 

[1911Tuner]

Good Things

"Tuner, the flush round and the minimal fore aft barrel movement. Does it mean anything good?"
*******************

Probably...but it's not a guarantee. As a wise man once said...can't remember who offhand, but I think it was Ned Christiansen...

"I only know what I can measure."

You can use strips of paper of a known thickness and get a close idea of the endshake by placing them between slide and hood and letting the gun go to battery. When you get to a thickness that won't let you pull it out without tearing it...measure that and subtract .001 inch, and you'll be close.

Measure the length of a fired case and slip it under the extractor and into the barrel...slide off the frame. Let the barrel drop slightly and slip the paper strips between the rim and the breechface. Push the barrel back into the slide. When you feel a good amount of resistance in getting the barrel all the way up...measure the strip and add it to the length of the case. Again...not precise, but it'll get close. If the total is more than .920 inch, headspace is excessive. If it's below .898 inch, the headspace is below minimum...which you probably won't find in your gun.

Excessive doesn't automatically mean that it's dangerous...only that the length of the chamber from breechface to shoulder is beyond ordnance allowable spec.

 

[batoy1911]

paper strips

Thanks for the instruction on how to measure the headspace using only a fired brass and some paper strips. I might get myself some feeler gauges though to make things easier and a little bit more accurate… I need to check the headspace every now and then anyway, right?

Tuner, can I remove the extractor while doing the measurements? Thought it would make putting in the fired brass in the chamber during the exercise easier.

Just got a package from EGW the other day. The OS FPS with square bottom is now in the Nork. Took awhile to file it down to where it would just snap into place with finger pressure.

 

[batoy1911]

Static Headspace

Finally got those feeler gauges, brought them to a local machine shop to have them tapered down to around ¼ inch at the tips.

So with the ARMSCOR "drop-in" barrel in the Nork slide;
End shake = .009
My fired brass = .888
I could get the .023 gauge (but not the .024) in between the brass head and breech face with the brass in the chamber and the barrel pushed forward in the in-battery position in the slide …the rounds were not flush with the hood after all (my eyes are getting tired after years of hard use it seems and your friend Ned was right).

.888 + .023 = .911 static headspace. Correct?
That gives me ‘bout .009 allowable setback before the max .920, IF my measurements were accurate.

When the barrel was new (unfired) the differences between front faces of barrel lugs to hood AND backside of slide lugs to breechface from 1 thru 3 were .009, .010 and .019.
I got the chance to measure the headspace after a few hundred rounds. At that time the 2nd lug was already in contact with the slide meaning the 1st lug has seated about .001 inch back (barrel lugs 1 and 2 equalized). So, at this time that the static headspace is .911 the 3rd lug is ~.009 shy of touching the slide lug. Now, I only need to watch the face of the 3rd barrel lug for signs of contact with the slide before I would again seriously measure the static headspace - because by then headspace would have grown to .920 or thereabout.
Tuner, am I good to go?

 

[1911Tuner]

re:

Batoy wrote:

>.911 static headspace. Correct?
That gives me ‘bout .009 allowable setback before the max .920, IF my measurements were accurate.<
**********************

.911 is close enough for government work, I'd say. You may have more allowable setback than that. "Headspace" is defined as the difference between the case length and the static dimension. The static dimension only tells you the length of the chamber from breechface to stop shoulder...not which direction the extra headspace comes from. For instance, if your gauged dimension was exact, you have .013 inch over the .898 minimum.
That excess amount can come from the chamber being cut too deep or from the amount of breech opening allowed when the gun fires...when the barrel and slide are pushed in opposite directions, before horizontal lug engagement.

If that .013 inch is evenly divided between the two...which is probably isn't. you have .0155 inch (.009+.0065) of setback allowable before headspace becomes potentially dangerous...which would also put it a little over the .920 inch maximum.

So...go back to the ordnance NO GO gauge to tell you when things have gotten excessive. If the gun goes to battery on a .920 NO GO gauge...it's out of spec.

 

[batoy1911]

It’ll take me a little more time to digest the numbers you just sent. Tuner.

I think I’ll go out and shoot some more… comfortable in the fact that I have a safe 1911 in my hands that will not send hot gases and pieces of brass down the mag chute anytime soon…

Since I’m still trying to understand this headspace thing: does wear on the shoulder of the chamber and wear on the breech face contribute significantly to the increase in static dimension with use or is it insignificant compared to the wear on the locking lugs?

 

[1911Tuner]

Wear

Batoy asked:

>Since I’m still trying to understand this headspace thing: does wear on the shoulder of the chamber and wear on the breech face contribute significantly to the increase in static dimension with use or is it insignificant compared to the wear on the locking lugs?<
***********************

I wouldn't say that it would be a signifigant contribution, but anything that can wear will wear sooner or later...and any wear that contributes to increasing the static dimension will increase the working headspace.

To help you digest the numbers a little easier...

If you start with theoretically "perfect" minimum headspace, in which not only the static dimension is minimum, but also the barrel and slide specs combine to create a case that is located in the chamber so as to provide the maximum case head support. This theoretical perfect barrel to slide fit has
zero endshake, and all lugs are bearing equally in the horizontal engagement.
This is also known as "Zero Headspace."

We also assume a theoretical case length of .898 inch.

If you remove .005 inch from the face of each lug, you have .005 inch of headspace and .005 inch breech opening under pressure. This is an increase in headspace in the dangerous direction. Equate it to lug setback/deformation.

If you simply reamed the chamber deeper by .005 inch, you'd still have .005 inch of headspace...but you don't lose case head support. This is an increase in the "safe" direction. Equate this with short case length.

If you ream the chamber AND remove material from the lugs, you have .010 inch of headspace...half of which is in the dangerous direction and half in the safe direction.

Remember...Static headspace only changes with wear, and lug setback and deformation. Working headspace varies with case dimension. In your theoretically perfect gun, one round may have zero headspace, and the next one may have .010 inch...such as with your .888 inch test case. With the short case/deep chamber, the potential negative result is mainly erratic primer ignition...or misfire if it's excessive.

So...Headspace comes from two directions, and most factory guns provide it with a little of each. The GO and NO GO gauges only tell you that the chamber length from breechface to chamber shoulder is within allowable tolerances. Into battery on the GO gauge means that the gun will chamber the longest case that is within SAAMI spec. Into battery on the NO GO means that the static chamber dimension is outside of acceptable parameters.
It doesn't necessarily mean that it's dangerous...only that it's not within allowable tolerance.

 

[batoy1911]

trying to understand

Tuner, the theoretical part was easy enough to understand. It was the numbers that got me all confused. So please be patient with the following d_mb questions/assumptions...

"If that .013 inch is evenly divided between the two...which is probably isn't."
------------------------------------
In my barrel/slide setup, the .013 departure from the minimum .898 would be .009 of breech opening (endshake?) and .004 deeper chamber over the minimum .898 = .902 distance from chamber shoulder to end of hood (or .888 brass + .023 feeler gauge = .911 - .009 of breech opening = .902 - .898 SAAMI minimum = .004 inch deeper chamber than minimum).

I have a tendency to over analyze, so if this is the case, please don't hit my hands...

the ".0155 inch (.009+.0065)"
------------------------------------
is based on the assumption "if the .013 inch is evenly divided..."? Which .009 is this?
In my actual barrel/slide, this line would be... .018 inch (.009+.009) since my chamber is deeper by .004 and not .0065?

So, my total allowable setback would be .018?

This is giving me a headache:banghead: ...but hey, no pain no gain, right?

 

[1911Tuner]

Specs

Without havin' the gun on the bench with all attendant gauges and measuring tools...I'd say that the endshake is making up the bulk of your .013 inch of headspace...which would make it in the bad direction...with the remainder being in the chamber depth. Again...this is no more than a guestimate...but it'll getcha pretty close.

Other factors that would change the bottom line would be chamber diameter...Barrel ramp geometry...(Over-throated)...operating pressures of the ammunition lot...and brass thickness and/or hardness.

Strong brass that is thick in the area forward of the web won't pose as much danger of case bulge/blowout with standard pressure ammo as would +p loaded in thinner brass. I've seen barrels that were grossly over-throated that didn't bulge thick brass...and seen a few that appeared to be okay, but with just a little too much headspace in the wrong direction that bulged it to the point of rupture. The clasic "Guppy Belly" appearance.

Final analysis...Keep an eye on the fired brass and listen to what it's telling you. Don't ignore even a slightly bulged case.

 

[batoy1911]

Thank you so much for all the info, Tuner.

Now I feel a lot more comfortable with this set-up. I know it's not perfect but feels that it's much better than with the original Nork barrel. Armed with all the new knowledge, I'll keep an eye on those brass...

Stay healthy, all of you...

 

[batoy1911]

Photos

Sorry for getting back to this old thread. I recently got a PM from one forum member who was interested to know about how the Nork with the ARMSCOR barrel is doing so far. I promised him some pictures. Here they are.

 

[batoy1911]

VIS

Just one more.

 

[1911Tuner]

Uh-Oh

Batoy...Unless the light is playin' a trick on my agin' eyes...you've still got a problem. Take another shot of those lugs from the side for me.

 

[HSMITH]

They look rolled to me too Tuner.........

 

[1911Tuner]

Rolled Lugs

Dangit! There's either a linkdown/drop timing problem or not enough clearance between the barrel and the slide when the barrel goes to bed.
Sorry batoy...This pistol's been a real pain for ya.

 

[batoy1911]

More picts of Lug#1

Hi Tuner, HSMITH,

Here are some older pictures of the barrel. The last in the series was taken today just before I applied some cold blue on it.

Is it the shiny portion at the top of lug#1 just at the front corner? I noticed that earlier on, so I decided to take photos to monitor how bad it will become.

Some more info on the gun;
The shiny wear mark on top of lug#1 started to appear after only a few rounds. I was using Link#3 then.
Some time ago, I decided to replace the Nork slidestop with an EGW OS slidestop. With the .278 link, there was a noticeable lower lug/slidestop pin binding. The slide would not totally close if it was allowed to go to battery slowly. I slight push at the back of the slide and the slide would snap shut. I replaced the link pin with the Marvel +3 (.281). It made the gun function smoothly. Gun was reliable with hardball.

Tuner, with you (and HSMITH) around it becomes less of a pain and more of a learning opportunity.