That AR Action & Troubleshooting

[Panzercat]

Was finally able to take the AR out to the desert to shoot and the results were... Well, lets just nearly everything that could conspire against me did Wednesday saw inclement weather roll into town and while the day started off fair, it rapidly turned wet and cold. Normally I'd welcome this weather in Phoenix, but on the day of my new toy's first outing it got pretty cold with me dressed a tad to light for the shift in climate



The weather wasn't the only thing out to get me. My semi automatic AR15 decided it wanted to be a single shot, bolt action rifle, consistently short stroking. The charged round would fire, the rifle would short stroke and fail to feed the next round until the bolt was manually cycled. My shooting buddy insists it's a buffer tube break in issue combined with a poor choice of range ammo. Okay, so Tula 55gr steel wasn't the best stuff to buy. Don't judge

He seemed to be right. By the time the weather had forced our retreat, we had managed to coax three rounds strings out of my new acquisition. The diagnosis seemed to be use heavier ammunition to break in the buffer and leave the bolt back when stowed for the same reasons. Hopefully my next range visit will yield better results... And weather :p

[cas]

Brand new gun, with hard extracting steel cases, and often under powered loads could certainly cause it to short stroke.

Lube the snot out of it while it's still new, drown the bolt carrier in oil and see if it helps. I'm not a "run them wet" guy, but it certainly helps when they're new.
You won't know anything till you try some other ammo.

[1894c]

Brand new gun, with hard extracting steel cases, and often under powered loads could certainly cause it to short stroke.

Lube the snot out of it while it's still new, drown the bolt carrier in oil and see if it helps. I'm not a "run them wet" guy, but it certainly helps when they're new.
You won't know anything till you try some other ammo.

OIL is your BCG's best friend... :)

[vancelw]

That's the ONLY misfires I've ever had with an AR

I shot 80-100 rounds of Wolf ammo at the range one day...neglected to clean my rifle like I usually do immediately after.
Next trip, fired another 80 to 100 rounds. The last two would not go off. Replaced the firing pin, still no go.

Cleaned the (filthy) BCG and oiled it up...back to functioning.

When shooting the AR, especially with cheap ammo, I usually spray some degreaser down the chamber and let it run out of the barrel at the range (to get that pesky lacquer washed away), then do a thorough cleaning when I get home. I got busy and didn't do it that ONE time. Never again.

[MrMurphy]

Never seen a buffer tube need "breaking in".....


Cheap, underpowered ammo is the culprit. Possibly a gas port issue as well, depending on who made it (don't remember your brand) and if it's a carbine or midlength gas system. Looks like a mid from the pics.

[fordwannabe]

Tear it down remove the oil grease and other lubricants and then give it a good swabbing with frog lube and you'll be GTG. I had the same issue with my last build and switching to frog lube fixed it in 2 shots. Tom

[OldWin]

I think before I did anything, I would just try different ammo. If it works as it should, you will know what not to shoot in it ever again.
I may be wrong, but I would suspect the ammo more than anything else. While I'm not the biggest AR guy, they usually run better than that, new buffer spring or not. That coated steel cased stuff doesn't extract well in straightish cases. it works fine in AK's because of the taper in the case body of 7.62x39. Also, take a look at the extractor of an AK compared to an AR. Steel case ammo is murder on most US designed rifle extractors. I won't shoot it in my M1A's either.


Just ignore this if I'm full of it.


Oh, and nice TJ. A guy with that kind of taste in vehicles can in no way have a defective rifle.

[Panzercat]

Yeah, the ammo wasn't the best idea. I guess if I wanted to shoot steel I should have gotten an AK :p
She's soaked in lube so next time I'll get some heavier brass to feed and see how we do. It helps not to be a newb too, I imagine

[OldWin]

A lot of the steel cased ammo is polymer coated. When the round is fired, the heat melts it and it makes a sticky mess that inhibits extraction.
Originally, and with some brands still, the steel cased ammo was lacquer coated. This was better than the polymer coating and what the eastern bloc military spec originally called for I think.
I think you will see an improvement with some good NATO spec, brass cased ammo.

[jnyork]

I love your portable bench rest.

Thorough cleaning and ample lubrication, load up some decent ammo, you'll be fine.

[Streetstar]

Just the fact that the ammo is steel isnt the problem. The ammo being Tula though could be --- i have heard numerous reports of it being loaded too weak to cycle the actions in a lot of semi-autos . Even the pistol ammo.

But........ Dont tell anyone--- i was using Tula in my M1A 2 days ago to get it roughly sighted in without a problem --- it was 308 though, not 7.62. A weak batch of 308's is likely still close to 7.62 level in pressure , But it is the opposite with the smaller round-- 5.56 is supposed to develop a bit more pressure than 223

I dont plan to make a habit of shooting steel, but something originally designed as a battle rifle should be able to withstand a few magazines of the stuff. Others run nothing but steel in AR's and Hornady even makes steel training ammo

[7.62 Precision]

Buffer spring is good or it is not, and there are bad ones out there, but they don't need break in.

Here are the things I have seen causing problems with new commercial rifles:

Lack of lube.
This is the number one reason I have seen semi-auto rifles fail to function. Almost any time I hear of a problem, especially with a new rifle, lube will make it go.

Rough internals
Rough finish and machining increase friction until the rifle has a chance to smooth out with use. Pick up a brand-new DPMS and a well used issue M16 and cycle the actions - you will be amazed at the difference. The new rifle will feel very rough and gritty feeling. Lube is your friend.

Out-of spec dimensions
This can cause all sorts of problems, but some will go away with wear. Things like magazine catch locations, interior dimensions in the upper, cam pins that have to be hammered in and pried out, buffer tube threads cut wrong on the receiver or tube, allowing the tube to be misaligned, etc. An out-of-spec firing pin can completely lock an action when the hammer hits it and jams it into the bolt. When people find that some brands of magazines work and some don't, it is usually because the dimensions of the rifle are out of spec to the point that that particular rifle wants an out-of-spec magazine.

Holes drilled in improper locations
This can put things out of whack in the trigger group and cause binding and other more dangerous issues.

Gas port located improperly
This can be because the barrel was drilled in the wrong place, the gas block was drilled in the wrong place, the gas block is installed incorrectly, or a hole is too small. I see this a lot, and very often, it is not enough to stop a rifle from functioning, but to make it function marginally. I saw a factory rifle in New Zealand recently that the gas block was so canted on that when I pulled it off, only a sliver of the port was aligned with the gas block, yet it still functioned. I have seen rifles fail to function with less of the port blocked. The problem is any other less than favorable condition then stops the rifle.
If you pull the gas block off, you can see by the carbon where it aligns with the port.

Chinese-made buffers
These gall against the interior of the buffer tube and the aluminum actually smears. They really create drag and will stop the rifle from cycling.

Improper ammo
Tula ammo is notorious for being underpowered. I have never shot ANY Tula ammo that will cycle either of my vz.58s enough to lock the bolt back on the last round, even though the rifles cycle. Surplus 7.62x39 will lock the bolt back every time. I have seen some lots of the cheaper Winchester and Federal 5.56 ball also fail to cycle ARs that would cycle fine with everything else.

Steel-case 5.56 (not lacquer coated) should cycle fine in a 5.56 AR, but if the chamber is a little tight, you may notice issues with steel case ammo that you would not notice with brass. More importantly, there is a lot more friction with steel-cased ammo, so it does not slide as easily from a magazine, or feed a slickly as brass. This, combined with a new, rough rifle that has not smoothed out yet, could be enough to stop feeding.

In your case, with the short stroking I would look at these three things first:
1. Lube
2. Lube
3. Lube

Next, I would try different ammo.
If you are buying commercial ammo, Black Hill's remanufactured ammo is really good stuff, and priced competitively. They will ship it to you or your dealer if you buy it by the case. They are very consistent in quality control, and I even shoot their reject ammo, most of which looks about the same as other brands' off-the-shelf ammo.

Third, I would check the gas port to make sure it is aligned.

Also, if you think the buffer or spring could be an issue, then try a different one - one you know is right. However, don't try to make adjustments to the buffer or buffer spring (lightening them) in order to compensate for other issues - fix the other issues and leave the buffer and spring alone, if they are good.

[FWiedner]

In your case, with the short stroking I would look at these three things first:
1. Lube
2. Lube
3. Lube

What, exactly, are you trying to say?

[m.wun]

If you were shooting 223 try 556! The extra pressure may help cycle the bolt better.I know of two guns that do that.

[7.62 Precision]

In your case, with the short stroking I would look at these three things first:
1. Lube
2. Lube
3. Lube

What, exactly, are you trying to say?

Let me rephrase that:

OIL!

[7.62 Precision]

If you were shooting 223 try 556! The extra pressure may help cycle the bolt better.I know of two guns that do that.

This could be, but it is a symptom, not a solution. Again, we are talking about guns that are marginally functioning. If it does make the difference, then the next step is to figure out why (though it could just be underpowered .223 ammo).

[ethang]

Give it a good 500 or so cycles while your watching your favorite tv show before your next outing. Then as others have said, give a a really good shot of oil and try some better ammo. See if that doesn't cure the problem.

[Panzercat]

So, um, lube?

Gah, I really hope it's not an out of spec upper. So oil it bunch (already done) and feed it some halfway decent ammo. I thought my inital application was enough, but I might have been too stingy in retrospect. I'll be honest, I was kind of suspect of the buffer tube advice. I mean, I can press in on it just fine with normal thumb pressure... but then I was the newb, so what the heck, can't hurt. I'll try the cycling drills... WITH LUBE.

And if i haven't mentioned it yet, you are all still completely awesome.

[Old Ironsights]

In your case, with the short stroking I would look at these three things first:
1. Lube
2. Lube
3. Lube

What, exactly, are you trying to say?

Let me rephrase that:

OIL!

(Caveat: Unless you are north of Anchorage in the dead of winter... where gun oil turns to glue...

(IMEX, absolutely clean & dry + graphite works best at -70 deg F. ... )

[cas]

Graphite and aluminum together are bad juju chemically. Uncle Sugar says "don't do that!"



On top of all the other things, new AR's have leaks. lol Once all the gaps carbon up a little they tend to run a bit better too.

[AJMD429]

Graphite and aluminum together are bad juju chemically. Uncle Sugar says "don't do that!"

What's bad about that combination...? I always wondered if that 'graphite lock lubricant' would have a firearm application.

[cas]

We had this discussion on another board years ago and the resident chemist explained what actually happens between the two, but basically the graphite eats away at the aluminum. I've heard from a few people about using graphite power as lube in Iraq, without issue, I guess maybe it's a longer term thing and also, if it's not your gun who cares.

The army mentions it in one of the "comic book" publications for the troops, I might still have it somewhere.

[Old Ironsights]

Graphite is just Carbon... And Ball Ammo spits carbon into the action by the bucketful...

[cas]

Go argue with the US Army, not me.



I no longer have the pertinent info, nor the whole "pamphlet" (pdf) but I do what the one page from the pub.

[Old Ironsights]

Army manuals also gave explicit instructions on how to wear single layer "cold weather gear" in such a way as to get a troop just sweaty enough to die of hypothermia... if he didn't die of hyperthermia first.

I wore wool.

[horsesoldier03]

In Desert Storm, we did use graphite. My guess is that pamphlet was created following our return.

[Old Ironsights]

We had this discussion on another board years ago and the resident chemist explained what actually happens between the two, but basically the graphite eats away at the aluminum. I've heard from a few people about using graphite power as lube in Iraq, without issue, I guess maybe it's a longer term thing and also, if it's not your gun who cares.

The army mentions it in one of the "comic book" publications for the troops, I might still have it somewhere.

If and only if you are in a humid environment.

In a Hot but Dry environment, liquid lubes work better.

At sub-zero temperatures liquid lubes aren't - and there simply isn't enough ambient moisture to allow for the galvanic corrosion that is possible with graphite.

Would I run it anywhere but the Arctic? No, but it sure as snot worked better at NWTC than anything else we had available in the late 80s...

[JReed]

7.62 is right
Lube that bad boy up till it is sloppy. That is the number one thing I have learned in 19 years of having to shoot one for a living. Unless it is dust storm conditions that bolt needs to be wet.