Sticky casing or chamber

AR/M4 AR Technical Discussion
1

So, just yesterday I was issued a new rifle as part of our team’s Intermediate Sniper program, an Armalite M15 (.223). The program is intended to bridge the gap between the perimeter team and the snipers, in order to provide closer range or interior precision fire to the entry team. The barrel isn’t chrome lined, so I was directed to do a break in to start off. During the 100 round shoot and clean period, I noticed that on several (probably 10) relays, I would get a stuck cartridge when I went to initially load a round. The bolt would go forward, and I could pull the trigger and drop the hammer, with a click and no bang. I would then have a ridiculously difficult time pulling the CH and extracting the round (which had no primer indentations). Rounds that had to be extracted had some scrapes on the sides, and fed fine manually. Other times, the bolt would slam almost all the way forward, except for the last 1/8" or so, and the FA wouldn’t help. This would affect only the first round loaded off the top of the magazine, and not the others; they would feed fine. This stopped occurring around the last 20 of the 100 rounds of the break in Shots were good; no keyhole-ing or true flyers that couldn’t be blamed on the nut at the end of the stock, and at the end of the break in I was able to sight in and qualify with no difficulty. My partner had a similar experience on his gun.
So, WHAT WAS CAUSING THIS? My thoughts immediately ran to these options:

  1. chamber dimension issues. Not sure if the chamber is chrome lined or not, or if the chamber needed break in as well.
  2. Magazine feeding issues.
  3. moisture freezing in the chamber or on the bolt face. I had heard about this somewhere, maybe here, and given the variables, this is what I’m leaning towards.

HERE are the variables:
-Brand New Armalite M15A4-T Upper mated to an older Armalite lower. Chambered to .223
-Barrels (according to bosses) are not chrome lined, though I can’t find anything from Armalite that says so. The older barrels that they had weren’t though.
-Magazine fed from a PMAG 20 rounded, and I only loaded the exact amount of rounds for any particular string of fire during the break in (1 round, 2 rounds, 3 rounds, 5 rounds, or 10 rounds). As noted above the 10 round strings went fine, and a 20 round string shot later, as well as the qualifier, went fine.
-Ammo is Hornady 75 Gr TAP, straight out of the box. This is both our practice and duty load, and per the bosses this is the only ammo that will touch the chamber.
-Break in procedure: shoot 1, clean 1 for 10 rounds. Shoot 2 clean 1 for 20 rounds. Shoot 3 clean 1 for 30 rounds. Shoot 5 clean 1 for 20 rounds. Shoot 10 clean 1 for 20 rounds. RC=100 rounds.
-Shooting was done on an outdoor range, and the cleaning was done in an unheated tent right at the range. We used a light cleaning solution occasionally.
-25 degrees and random light flurries. Hence my belief that weather is a factor.
Thinking forward, regardless of whether or not the break in worked out the problem, the charging handle got quite a work out. I’m probably going to upgrade to a Gunfighter handle so I can get a better grip, so I don’t worry about torquing the handle.
So, what say this qualified membership? Am I right in thinking that the weather is a likely culprit, or could something be out of spec with the Armalite chamber?

2

Armalite chambers are known to be tight last time I checked. Were you shooting 5.56 8126N TAP ammo or the .223 version? The barrels should at least be chrome moly, but I would call Armalite directly and ask them.

It could very well be a break in issue, though I haven’t had that problem with anything that I have assembled or purchased that was within spec.

3

It was .223 TAP.
I’m wondering now if it was the sh**ty cleaner that I was patching through the gun from time to time. If I didn’t run enough dry patches through, i suppose its possible that the solution could have frozen or gummed up a bit in the chamber.

Good point on the tight chamber. I noticed that I couldn’t push a Dewey cleaning rod with a patch down my barrel. Rod only, OK. Rod and brush, OK. But for patches, I had to use a collapsible field rod. We’ll try to call Armalite very soon.

Thanks for the heads up.
BTW I did a search for this and didn’t come up with anything specific to my problem. There was one from about a year ago, but the guy refused to accept that his reloads were out of spec and causing the jam. I figured that since we’re using Hornady, we should be good on the ammo QC. Just didn’t want to be That Guy.

4

The bolt locks forward find on an empty chamber correct? Only when loading ammo?

25 degrees should not affect weapon performance.

What lube are you using?

Definitely clean the gun well, and get all the cleaning solutions out of the receiver. I personally use brake cleaner to blast out all the loose crud, old lube, and fouling AFTER scrubbing everything down with a dedicated cleaner such as Hoppes or Slip Carbon Cutter. Brake cleaner evaporates off very quickly so it doesn’t leave anything behind. If you try this you will need to relube the weapon as brake cleaner will take everything off. It works the same as “Powder Blast” but is about half the price. Don’t let it get in your eyes or sit on your skin. I recommend Slip EWL oil. Stay away from grease on an AR. Lube the BCG well including down the cam pin hole, down the gas key, shiny spots, and in the gas ports on the side of the BCG.

Use a USGI chamber brush.

What size patches are you using? Often times patches come too large for a 223 barrel, and have to be cut down.

Check the feed ramp area and chamber for burrs that the round could be getting caught up on. Are the marks on the brass just light surface scratches or are they deep gouges? Light scratching is fairly normal. Anything beyond that would likely indicate something is messed up with the feed ramps and/or chamber.

Check the bolt face, bolt lugs, extractor, and ejector for burrs and proper function. Specifically check the extractor to make sure it can latch onto the round. Use a tool to push the ejector in. There might be a burr catching on the ejector so the round cannot seat on the bolt face correctly, and then causes the jam where it wont chamber all the way.

Fully assembled rack the BCG slowly and see if its getting caught up on anything.

Check to make sure the gas tube is aligned properly. Just do a visual inspection and see if its parallel to the upper. Check the gas key on the BCG to see if the “opening” is marred, and do the same on the end of the gas tube. If the two are not aligned well they will hit each other causing marks you should be able to see easily.

Check the recoil spring to see if its adequate in length. Maybe its too weak to push the BCG home reliability. You said its an older lower so it might we worn out. Minimum length is 10 1/4". A new spring will be closer to 11". I personally replace them 10 1/2" and below.

Make sure you are shooting ONLY .223 spec ammo out of that weapon. 5.56 pressure ammo is not designed to work in a .223 chambered rifle and can be a safety risk.

BCM Gunfighter is a good mod. I have them on all my weapons now…:wink:

5

Wonder if the ogive of the bullet is engaging the lands?

Look at an extracted round and see if you see evidence of the rifling contacting the bullet.

If so, a visit from Ned C’s Reamer would be proscribed.

6

Phew! Will do.
Bingo on the grease; I noticed that when we unpacked these things there was a decent layer of grease on the bolt. I’m thinking now that some of whatever they packed the receiver with got burned up during the shooting, and might have gummed up the chamber. As noted, after about 80-90 rounds it went away. Then when cleaning, the stuff was coming off in chunks. Chunks I tells ya, not flakes.
The bolt functions fine with no round loaded. The gas key and tube look good. Patches and dewey rods oddly enough ran through fine after the day was done and I broke it down to clean.
Lube is whatever crap the county puts in the cleaning room. Currently CLP I believe. I have Militec at home, and I’ll probably get some Slip 2000 products to clean these guns.
Good call looking at the recoil spring. I hadn’t thought of that.:slight_smile:
The ogive isn’t connecting, and the gun’s shooting straight. The ejected rounds had their scrapes on the casing, not the bullet. Once it started shooting, the gun would cycle fine.
I guess I’ll just have to take it back out and shoot it more. Darn.

7

Those heavy and tacky preservative greases they coat weapons with should be cleaned off before shooting the weapon. Its there to prevent rust…nothing else.

Slip EWL is very good lube and will not burn off as quickly as CLP. CLP works ok but better stuff is on the market. Militec failed many of the military tests JFYI.

Carbon cutter is a good non-toxic cleaner that works well. I scrub everything down with it using a USGI brush, and then spray everything off with brake cleaner. Wipe everything down with an oily rag, and then lube the BCG as noted above. Wipe down exterior with a dry cloth, and it will leave behind a protective film to prevent rust.

Everyone has their own cleaning methods, and some take offense to using an automotive cleaner to clean a weapon. Powder Blast does the same thing but costs twice as much.

Id also be careful about cleaning that bore. USGI rods are very harsh on the bore. Id always use a coated rod like the Dewey. Shame they didn’t come chrome lined. They figured out non-chrome lined barrels suck in the AR system back in the 60’s when the M16 was first issued. Chrome is far harder than steel, and makes for a longer lasting barrel that is easier to clean and keep rust out of.

8

Here is a post on a similar subject I made a few days ago.

"What Im talking about is the lightly marked ring around the fat part of the bullet before it starts its taper to a point just in front of the cartridge case neck in the “after” pic.Also looks to me like there might be individual rifling marks spaced evenly on the bullet right in front of the ring I mention.Again could just be my eye balls and OCD since nobody else has commented on it.

But it caught my eye due to the fact I had this same indicator on some short leade Armalites years ago with some different brands of ammo.The primers will usually be very flat from the increased pressure if the bullet is forced into or touching the leade due to lack of jump.

A simple redneck test I used to determine the condition with different brands of loaded ammo was to remove the upper from the lower,remove the BCG and clean the chamber very well with a chamber brush and solvent.Patch dry,inspect for spotless clean,and then take one of the cartridges in question and drop it in the chamber,give it a light push with a finger tip on the case head to make sure the round is firmly seated in the chamber.Tip the muzzle up and if the round drops out of the chamber/receiver o.k…if it sticks in the chamber,lightly tap the round out with your cleaning rod from the muzzle and check the bullet to see if its marked by the rifling on the ogive.If its marked it could lead to pressure issues.

Only issues I ever really had with the tight leade chambers was with the longer heavy bullets above 60gr…for the most part.Although some Q3131A and particularly Wolf 55gr. loaded to the long side,or that used bullets with a more foward placed ogive,typical of some soviet ball ammo…which would force the bullets ogive into the leade of the chamber and cause some pressure issues."

As for the Armalite or Eagle Arms non-chrome barrel uppers,I can say for a fact that Armalite installs the CRANE type o-ring under the extractor of all their BCG’s no matter carbine,mid or rifle length.The o-rings they use are not the proper composition and are exceptionally stiff IMHO,with excessive tension applied to the extractor.The Armalite BCG’s had such extractor tension that I would say to the point of binding and would loudly clank on the cartridge when going into battery and cartridge case rims chewed as a result.The excessive extractor tension also seemed to cause the cam pin to bear/peen the upper a bit more than usual adding to the friction of the action…
At first I suspected that there may have been a tolerance issue within the extractor channel of the bolt,or possibly the extractor.It was so excessive that the extractor was very difficult to move even with a screw driver.
On my rifle uppers I saw the same type issues you describe and was what I would almost call bolt bounce.After a couple hundred rounds the feeding improved but the extractor claw had already started showing excessive wear.Removed the o-rings(per the members here) and the rifles ran better.Shortly after that the extractor springs went flat and the inserts deformed.
I installed a BCM SOPMOD bolt upgrade kit and all was well.Shortly after that I upgraded the BCG’s to LMT and have not seen an issue since.

To further add the action/buffer springs that Armalite uses should be changed as well as Ive found that some tend to take a huge amount of set in short order and its a shot in the dark of when…
HTH

9

Wow another outstanding thread here. You guys are just amazing, I swear every day I learn something on this site. After reading Blankwaffe’s post above I’m very impressed with the level of expertice on this forum…

10

A tip I got from 6.8forums is to rack the heck out of a new gun as part of the “breaking in” process. Make sure there’s no ammo around, pop in a Netflix, hold the buttstock against a hard surface, and pull and release until your arm hurts. Like 500-1,000 times. Make sure it’s lubed up, and pull the BCG out, wipe down, re-lube and keep racking. It helps get those edges mated and saves ammo/frustration at the range.

11

Thanks for the help everyone!
I’m going to try out some of these ideas in a couple of days at the range. I’ll keep you all posted.
Ranchman, that’s why I hang around here.

12

I doubt this is the “case,” but ya never know…

I had a run of oversized factory ammo which gave me that same problem. I put a mic on the remaining rounds (5 boxes) and all the necks were 0.002 over spec. I returned them, and the company made it right.

13

In a .223 chamered weapon the case dimensions are more critical because its a tighter chamber.

A 5.56 chamber is meant more for reliability than accuracy do to it’s “looser” dimensions.

The “fix” for this has been tried a few times most notably the Noveske chamber, and the Wylde which LaRue uses.

Also on a non-chrome lined chamber its naturally more “sticky” than a chrome lined chamber due to the softer material (bare steel). Same reason a chrome BCG is easier to clean than a plain USGI steel BCG.

Personally I think any non-SS barrel on an AR that is not chrome lined is just cheap, and can add problems that need not exist. As I noted before it was one of the problems our troops had in the initial fielding of the M16…