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My case lot of norc has a few more occasion of ftf then any other ammos. Probably has something to do with not enough crimp. Same gun running mfs and i dont have that problem
 
Problem solved.
Bolt's gas rings were in sequence. Came like that from the factory. Mixed them up and problem solved.
 
Short stroking.
If the bolt does not fully get behind the round in the mag it will still eject the casing and can still catch the round in a less than ideal way and jam it forward in a way less constructive than intended.

Some rifles will start catching the front edge of the BCG (instead of the bolt) on the bolt catch and will then jam the first round from a new mag following a "locked" to the rear reload.
 
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There is no such thing as a barrel sleeve.

The "feed ramps" or bullet guides are machined into a barrel extension that has the locking lugs that is threaded over the rear portion of the barrel. This contributes to headspace along with the .330" dis of the shoulder and the bolt. The front of the locking recess is the barrel. The chamber is part of the barrel.

That damage is on your therefore on your barrel. Seems odd that a copper gilded bullet would dent a 4150 chrome moly steel, or even a stainless barrel.

Gunnerlove is most likely correct that it is short stroking.

Staggering gas rings does nothing. They rotate with every shot and a compete seal is never achieved nor required. There are three for wear and adverse conditions. The gap all but disappears when assembled. The gaps allows expansion of temperature and to conform to surface irregularity. Try this if you don't believe it. Place just one new gas ring on a serviceable rifle and fire a few hundred rounds. Your rifle should fire just fine at normal temperatures with one gas ring only.

Unfortunately insufficient gas is hard to diagnose because gas tubes also wear (at the ferrule). Loose keys or worn or scraped bolt tails also leak gas and a tilted or misaligned gas block will also create insufficient gas. Magazines can cause similar stoppages. Fortunately gas rings are cheap and easy to replace. There is also a gas tube gauge.

Riflechair said:
Howdy folks
I'm getting a FTF once in 50-150 rounds with several STAG metal and one P-Mag Magazine
Skipping over the M4 feed ramp and slamming hard onto the barrel sleeve and the bullet usually gets pushed into the case.

I've been mostly running Norinco 223 but it's also happened with two other brands of ammo.

Ever seen something like this?
It's like the ammo isn't sitting proud enough in the mag to feed reliably?

Another chap just ran 100 rounds down the barrel with different mags.
He ran pmags, AT15 mags, a beat up and mutilated metal 30 rounder, metal 5 rounder…
No FTF's....

Opinions?

http://rodandgun.netfirms.com/FTF/M4ramps.JPG
In this pic you can see the feed ramp on the right.
Look to the upper left corner - you can see where the bullet impacts have dimpled the barrel sleeve.

http://rodandgun.netfirms.com/FTF/Case.JPG
Here is what invariable happens to the case.
Click to expand...
 
Gunnerlove said:
Short stroking.
If the bolt does not fully get behind the round in the mag it will still eject the casing and can still catch the round in a less than ideal way and jam it forward in a way less constructive than intended.

Some rifles will start catching the front edge of the BCG (instead of the bolt) on the bolt catch and will then jam the first round from a new mag following a "locked" to the rear reload.
Click to expand...

What I meant is that it makes no sense that the gun short strokes with certain mags but not others.

And as Matt K says, gas rings needing to be staggered is a myth
 
If he was going 50-150 rnds between stoppages, going 100 rnds without a stoppage really means nothing.

In all honesty pulling the bolt and lubing everything up probably did more than staggering gas rings.
 
Ive had similar expierience with yellow box 93 or 95 headstamp Norinco ammo.

Its the ammo. Maybe it has to do with powder...or compromise during storage. But i dont think that many mags can give you a headache. Swap ammo and tell us what brand of rifle you are using.

Ive had the same double feeds and crushed bullets into the brass case. Id say maybe one in 2-300. You bought dirt cheap ammo, its going to be finicky. If the mags have any slight issues (spring strength, stretched mag lips) then its going to magnify the issue.

Keep shooting and working on your clearing drills.
 
Done this with multiple ammo brands including M885 62gr with a heavy crimp.
Not happy is an under statement but I'm going to see if the gas rings thing has fixed it (or not)
PS I. Always run the bolt wet...
 
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Riflechair said:
Problem solved.
Bolt's gas rings were in sequence. Came like that from the factory. Mixed them up and problem solved.
Click to expand...

lol, no thats not a solution lots of proven facts about this not having any impact.
if it "fixed" the problem thats a case of correlation, not causation
 
Gunnerlove said:
Short stroking.
If the bolt does not fully get behind the round in the mag it will still eject the casing and can still catch the round in a less than ideal way and jam it forward in a way less constructive than intended.

Some rifles will start catching the front edge of the BCG (instead of the bolt) on the bolt catch and will then jam the first round from a new mag following a "locked" to the rear reload.
Click to expand...

or it just marginally caught the round by clearing it just past due to a short stroke or it being very dirty, therefore when it comes back it is without enough inertia to slam it through

ive noticed that happening when i run an ar way too dirty
 
1)Thoroughly clean and inspect the rifle or carbine.
Does it have a carbine or rifle receiver extension?
Does it have the proper length spring?
Does it have the proper length and weight of buffer?
What length of barrel and gas system?
2)Function check the rifle.
3)Lubricate the rifle.
4) Mark all your mags so that each is identifiable.
Go out and shoot the rifle.
Don't mix ammo in the same magazine.
Mark every stoppage. which mag, which round in the mag, type of ammo, type of stoppage.
Every mag that has a stoppage should be taken out of the rotation till all of your mags have experienced stoppages.
If all your mags experience stoppages then maybe it isn't a mag problem.


From:
TECHNICAL MANUAL
ARMY NO. 9-1005-319-23&P
AIR FORCE TO 11W3-5-5-42

RIFLE: 11 3/4 Inches (29 85 cm)
minimum to 13 1./2 inches (34 29 cm)
maximum

CARBINE: 10 1/16 inches (25.56 cm)
minimum to 11 1/4 inches (28.58 cm)
maximum.
 
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Riflechair said:
Problem solved.
Bolt's gas rings were in sequence. Came like that from the factory. Mixed them up and problem solved.
Click to expand...

This is unusual to short cycling as the gas rings will spin and never remain timed correctly. An AR will run with only one good ring installed so yours maybe showing its time for new ones.
 
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