Barrel Timing

original: forum.m1911.org
Retrieved: November 26, 2011
Last Post: September 25, 2006

JMB-1911
18th June 2010

I recently purchased a Norinco 1911 and upon disassembling I noticed, what I characterize as flattening on the barrel lugs. I see no visible damage to the slide, so I believe I caught the issue in time before the slide was ruined. I have read that this is a common issue with the Norinco's. My question, for those who have had or seen this issue, what is a good barrel replacement, lug manufacture for this weapon. Were you able to purchase one "off the shelf" or have to have a gun smith fit it.


aedavis
4th July 2010

I bought a Norinco a couple years ago with the same problem. I didn't know anything about 1911s at the time and didn't realize it was an issue. Here's a picture of my original barrel: After some research and barrel swapping, I opted to fit a barrel from a Rock Island Armory Tactical model. I only had to do some minor fitting around the lower lug, but I got it working. After 500 rounds, the lugs still look new:

After some research and barrel swapping, I opted to fit a barrel from a Rock Island Armory Tactical model. I only had to do some minor fitting around the lower lug, but I got it working. After 500 rounds, the lugs still look new:

PICTURE 404


niemi24s
4th July 2010

Your first pic is the best example of barrel locking lug crash I've ever seen! Must be a testament to the strength of the Norinco slide if its lugs didn't suffer a similar fate. [Edit: Or maybe just a mushy-soft barrel?]


Slopoke
4th July 2010

...so what causes this? Is the hood too short?


SoulShade
4th July 2010

The barrels are hard-chromed!


niemi24s
4th July 2010

Its direct cause is the barrel's lower lugs hitting the VIS (and halting the aft component of the barrel's motion) before the link has had a chance to pull the barrel down enough to vertically disengage the barrel's radial locking lugs from the slide's radial locking lugs. As a result, the barrel tries to keep the slide from going back.

All that can be caused by a link that's too long or something out of spec on the barrel, slide or frame.


1911Tuner
4th July 2010

That damage isn't due to a barrel timing problem,and the lugs haven't "crashed" in any abnormal way. They crash every time the gun is fired. How well they stand that crash depends on the vertical lug engagement... which in this gun is insufficient.

The upper barrel lugs are bearing the brunt of the recoil forces at the top of the lug, instead of being evenly distributed, and bearing most of it low, in the corner... where it's stronger.

The damage is called setback deformation, and unless the new barrel has good vertical engagement, the problem is still present. The difference is that with harder steel... instead of straight deformation... the two forward lugs will eventually be ripped off the barrel and the rearmost lug will deform anyway. Headspace increases with this deformation.

I won't argue the point. I especially won't argue with drawings. Instead, I'll simply say that I've seen and corrected this particular problem in about 30 Norinco pistols since around 2002, when I first started seeing it.

Measure the height of the upper lugs. Determine the depth of engagement into the slide. If it's not at least 90% of the lug height... get thee to a smith who understands how to set it right. Be warned that it's fairly labor intensive... read that as expensive... but the results will probably be worth it. The Norincos are tough pistols that'll last a lifetime if all is well within the gun.


niemi24s
4th July 2010

How does your barrel compare to the first photo in Post #3? If it's significantly different, a photo of your barrel may help.

Here's one method for measuring the amount of vertical locking lug engagement recommended by 1911 Tuner...

...but if your barrel's deformation has increased its diameter, this method may give a false indication of engagement.


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