LMT AR Ejection issues

[emsjeep]

I recently had my bolt and carrier replaced by LMT due to a defective extractor (apparently it was machined incorrectly) that was rubbing the inside of the carrier and was jamming badly. They sent me a new carrier and bolt. Went out to try it tday and got through about 40 rounds of Wolf before it started feeding a new round in before the spent casing was fully ejected...it did this about 6 times in succession and then intermittently thereafter. Any ideas?

[d90king]

Rather than type out all of the fixes or cause its probably best for you to read the info I am linking you to that is written by SME's so that you get a better understanding... My guess is its mag or extractor related.

http://m4carbine.net/showthread.php?...t=double+feeds
http://m4carbine.net/showthread.php?...t=double+feeds

[ithinkimamedic]

Stop using Wolfe in your LMT. I had a similar issue and could not get it to reliably function. I switched to brass cased ammunition in that gun and haven't had a problem sense. I understand the alure of cheep ammunition but sometimes you can't skimp

[d90king]

Stop using Wolfe in your LMT. I had a similar issue and could not get it to reliably function. I switched to brass cased ammunition in that gun and haven't had a problem sense. I understand the alure of cheep ammunition but sometimes you can't skimp

Under powered loads can be a cause. That's why I wanted him to read all the info that I posted for him. The guys talking about it know their shit! Wolf runs in some guns just fine (I don't use it but know guys who do).....

[panther76]

Is it a f/a or s/a bolt carrier group? LMT sells both. Also, what type of upper is it, an LMT? This could matter.

The problem could be several things, depends on exactly what is going on with the spent casing. Is it extracting?

Check out the following reference and try to find something that matches exactly what is happening with your weapon.

Without more info it is hard to correctly diagnose, and could be as simple as a bad magazine, or as serious as a problem with the bolt they sent you.

http://www.globalsecurity.org/milita...3-22-9/c03.htm

[MTechnik]

Clean the chamber nicely.

Get a box or three of brass at wally world, then go shoot it.

Check the brass (won't necessarily show on steel casings) for marks to make sure there isn't anything dragging in the chamber. Also check the rim edge to make sure it's catching cleanly.

Do the more consistently powered rounds fire consistently?

How is it "jamming"? is it not extracting the round? is the new one not going in?

[Legion_Prime]

My money is on short stroking due to underpowered rounds. Insert 1 round in a known good magaine and fire it. If the bolt does not lock back then that's your problem, I would put money on it. LMT gas ports are sized smaller for milspec 5.56 and will sometimes not run underpowered .223 ammunition. Even 5.56 NATO may have issues (though not as likely) as US milspec is different from 5.56 NATO, the British 5.56 I know is slower than ours in order to run in their SA80's properly. Load up some Federal XM193 and you should be GTG.

[mythaeus]

If it fed the first 40 rounds, it sounds like a tight/dirty chamber that expands/squeezes just enough against the spent casing to slow it down.

I am not sure about Wolf being under-powered. Are you shooting 62gr or 55gr Wolf? My 3 AR's and the one I sold ate every Wolf fed to it. I think it's silly that you have to use more costly ammo to have an AR feed reliably. Shooting heavier ammo, 62gr Wolf, may help. If you're using an H or H2 buffer, consider downgrade to standard carbine buffer.

Another possibility is a small gas leak, just enough to reduce the gas impingement so that even a small amount of build up in the chamber can cause the jams.

Al

[emsjeep]

Ok, first, thank you...
The only range where I am now only allows HP or SP rifle ammo, hence the steel cased junk, HP brass is usually specialty ammo and is expensive.

It was 55 gr. JHP Wolf, perhaps I just got a bad box? I was having issues before and the bolt and carrier were replaced. The extractor was machined incorrectly and was catching the inside of the carrier.

The issue is specifically that the spent casing is not fully extracted before the new round is fed in, it looks like a double feed except one round is spent. The rifle was perfectly clean before this, chamber and all.

This is a F/A carrier and "H" buffer. I had short stroking problems initially with the F/A carrier and 2H buffer, this is not the same. Basically, if it goes back far enough to feed a new round it has gone far enough to extract and eject the previous round. Either its hanging up int he chamber or there is an issue with the extractor.

A single round fired always locks the bolt back.

The hardware makeup is as follows: LMT 16" standard flat top upper, EA (pre '94 ban for New York State) Lower, RRA LPK and Geissele DMR trigger, this was a new Magpul 10 round (blocked 30 round) mag that has always functioned perfectly (I'm in NY at the moment).

I'm going to read through some more of your links and see if anything pops out at me...thanks again...

d. Failure to Eject. Ejection of a cartridge is an element in the cycle of functioning of the rifle, regardless of the mode of fire. A malfunction occurs when the cartridge is not ejected through the ejection port and either remains partly in the chamber or becomes jammed in the upper receiver as the bolt closes. When the firer initially clears the rifle, the cartridge could strike an inside surface of the receiver and bounce back into the path of the bolt.

(1) Probable Cause. The cartridge must extract before it can eject. Failures to eject can also be caused by a buildup of carbon or fouling on the ejector spring or extractor, or from short recoil. Short recoil is usually due to a buildup of fouling in the carrier mechanism or gas tube, which could result in many failures to include a failure to eject. Resistance caused by a carbon-coated or corroded chamber can impede the extraction, and then the ejection of a cartridge.

(2) Corrective Action. While retraction of the charging handle usually frees the cartridge and permits removal, the charging handle must not be released until the position of the next live round is determined. If another live round has been sufficiently stripped from the magazine or remains in the chamber, then the magazine and all live rounds could also require removal before the charging handle can be released. If several malfunctions occur and are not corrected by cleaning and lubricating, the ejector spring, extractor spring, and extractor should be replaced.

[synergy]

Ok, first, thank you...
The only range where I am now only allows HP or SP rifle ammo, hence the steel cased junk, HP brass is usually specialty ammo and is expensive.

It was 55 gr. JHP Wolf, perhaps I just got a bad box? I was having issues before and the bolt and carrier were replaced. The extractor was machined incorrectly and was catching the inside of the carrier.

The issue is specifically that the spent casing is not fully extracted before the new round is fed in, it looks like a double feed except one round is spent. The rifle was perfectly clean before this, chamber and all.

This is a F/A carrier and "H" buffer. I had short stroking problems initially with the F/A carrier and 2H buffer, this is not the same. Basically, if it goes back far enough to feed a new round it has gone far enough to extract and eject the previous round. Either its hanging up int he chamber or there is an issue with the extractor.

A single round fired always locks the bolt back.

The hardware makeup is as follows: LMT 16" standard flat top upper, EA (pre '94 ban for New York State) Lower, RRA LPK and Geissele DMR trigger, this was a new Magpul 10 round (blocked 30 round) mag that has always functioned perfectly (I'm in NY at the moment).

I'm going to read through some more of your links and see if anything pops out at me...thanks again...

Is it leaving the empty in the chamber? Or is it loosing hold of it somewhere between the chamber and ejection port?