AR-10 Problem

[Lodge2004]

Went shooting Sunday with my brother-in-law and he brought his new Armalite AR-10 (.308). It was jamming after every round. It would either stovepipe the empty or try to double feed the next round.

We took it home and I disassembled for him. It was horribly dirty (my in-law hunts but is NOT a gun-guy). He had put a few hundred rounds through it without ever cleaning from the store, so it had some of the original packing grease around bolt carrier.

One thing I noticed was the bolt being very sloppy. On the AR-15, the bolt has a some friction because of the gas rings. There was no friction on the AR-10. Is that normal?

Was thinking there were several possibilities: Underpowered ammo (he was shooting commercial hunting ammo), bad gas rings, bad magazine (although he was using a new Armalite mag), ...

Any ideas?

[The Annoyed Man]

Any ideas?

Give it to me?

I don't know much about AR10's, other than I want one; but I would have thought that it was just a scaled up AR 15 in every way. Are there any other dissimilarities in parts?

[WarHawk-AVG]

AR-10 is just a bigger beefier AR-15

Were the gas rings offset like the rings on a cars piston (to keep blowby to a minimum)

Clean it up really good and try it again, its rare that you get "low powered" .308 that will fail to function an AR-10

How new is this rifle?
What kind of ammo??

Remember it takes upwards of a few hundred to a few thousand rounds thru a brand new AR to break it in properly...some good lube like (gun butter) goes a long way as well!

My older brothers dang near new Bushmaster varminter will jam EVERY ROUND on wolf or steel case ammo, but my buddies AR (generic build) that has approx 4K rounds thru it eats em up for lunch!

[Purplehood]

I recall something about the gas rings being lined-up wrong as a potential cause for jamming. Not sure, it has been years since I heard it or experienced it.

[Excaliber]

Went shooting Sunday with my brother-in-law and he brought his new Armalite AR-10 (.308). It was jamming after every round. It would either stovepipe the empty or try to double feed the next round.

We took it home and I disassembled for him. It was horribly dirty (my in-law hunts but is NOT a gun-guy). He had put a few hundred rounds through it without ever cleaning from the store, so it had some of the original packing grease around bolt carrier.

One thing I noticed was the bolt being very sloppy. On the AR-15, the bolt has a some friction because of the gas rings. There was no friction on the AR-10. Is that normal?

Was thinking there were several possibilities: Underpowered ammo (he was shooting commercial hunting ammo), bad gas rings, bad magazine (although he was using a new Armalite mag), ...

Any ideas?

A highly likely cause would be improper or inadequate lubrication of the bolt and carrier. Especially when combined with a dirty gun this can cause too much friction to allow these parts to move as designed during the ejection / feed cycle.

Many oils lose much of their lubricity after 40 or 50 rounds, especially when rapid firing heats up the gun. I'm not a gunsmith, but my solution (recommended by some very well respected tactical trainers) is high temperature / high pressure wheel bearing grease (available in the auto dept at WalMart for about $4 a tube). In my guns, it does an excellent job of keeping things slippery during extended firing when applied to both the bolt and the bolt carrier after the gun has been thoroughly cleaned. It works equally well on .223 and .308 rifles.

You might give this a try with the same ammo and see if it solves the problem.

[WarHawk-AVG]

Mobil 1 (15W-50) is a GREAT lubrication...its synthetic and will not burn off until the heat get VERY high and retains its lubricity for alot longer

Yes..Molybdenum grease is good..but its a booger to clean up, it attracts dirt like a magnet and when heated can get dirt/carbon mixed with it and then when cooled becomes a rock in the operational mechanism (I tried some regular wheel grease in my AK...after only a mag or two the inside of the rifle looked like the slobber box in a tank...much nasty goo!! I use light lube Mobil 1 now)

Actually those tubs are "low concentration" Molybdenum solution...go to a motorcycle shop and get their moly grease (the stuff they put on the splines of a shaft drive bike) it has a MUCH higher concentration of Molybdenum in it

Its best to keep an AR rifle lightly lubed, too much oil will cause it to poo up quick, plus it has a tendency to blow the excess right out in your good shooting eye (not good when shooting on qual day!)

Here I found this as well

Moly greases with 60% + molybdenum disulfide content:

* Honda Moly 60 paste, $9 for 3oz, pn 08734-0001 at your Honda dealer, or $8 from Kim Leong, STOC 3073, California Sport Touring.

* LocTite Moly paste, 65% molybdenum disulfide. $20 for an 8oz tube from Enco, part #505-1197, 800-873-3626

* TS-70 Moly Paste, 4 oz. ctg. $14 from TSMoly. (800) 508-5545

An alternative to moly is the new poly-flourinated lubricants made by DuPont called Krytox Teflon Bearing Grease. These chemicals are simply magic. They have almost no known solvents, are chemically inert, and don't burn at any temperature, even in a pure oxygen atmosphere. This is pretty clearly the only grease to use
Krytox is compatible with moly - in fact DuPont sells a high pressure Krytox which mixes the two. You may hear some horror story from some mechanic about mixing greases and the result turning radioactive or some such. Don't worry, it won't happen with moly or Krytox.

Krytox greases:

* DuPont XHT-AC extra high temperature anti-corrosive Krytox. $30 for a 2oz tube, pn 10195K25; $113 for an 8oz tube, from McMaster Carr.

* DuPont XHT-BDX extra high temperature extra bonding Krytox. $63 for a 2oz tube pn 10195K22; $230 for an 8oz tube pn10195K24 from McMaster Carr.

* LocTite Krytox HyperLube, pn 29711. about $35 for two ounces.

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[The Annoyed Man]

I use SLiP2000 products on all my ARs. They seem to work very well, except for the copper fouling remover. It doesn't work any better than anyone else's products.

[Excaliber]

Mobil 1 (15W-50) is a GREAT lubrication...its synthetic and will not burn off until the heat get VERY high and retains its lubricity for alot longer

Yes..Molybdenum grease is good..but its a booger to clean up, it attracts dirt like a magnet and when heated can get dirt/carbon mixed with it and then when cooled becomes a rock in the operational mechanism (I tried some regular wheel grease in my AK...after only a mag or two the inside of the rifle looked like the slobber box in a tank...much nasty goo!! I use light lube Mobil 1 now)

Actually those tubs are "low concentration" Molybdenum solution...go to a motorcycle shop and get their moly grease (the stuff they put on the splines of a shaft drive bike) it has a MUCH higher concentration of Molybdenum in it

Its best to keep an AR rifle lightly lubed, too much oil will cause it to poo up quick, plus it has a tendency to blow the excess right out in your good shooting eye (not good when shooting on qual day!)

Here I found this as well

Moly greases with 60% + molybdenum disulfide content:

* Honda Moly 60 paste, $9 for 3oz, pn 08734-0001 at your Honda dealer, or $8 from Kim Leong, STOC 3073, California Sport Touring.

* LocTite Moly paste, 65% molybdenum disulfide. $20 for an 8oz tube from Enco, part #505-1197, 800-873-3626

* TS-70 Moly Paste, 4 oz. ctg. $14 from TSMoly. (800) 508-5545

An alternative to moly is the new poly-flourinated lubricants made by DuPont called Krytox Teflon Bearing Grease. These chemicals are simply magic. They have almost no known solvents, are chemically inert, and don't burn at any temperature, even in a pure oxygen atmosphere. This is pretty clearly the only grease to use
Krytox is compatible with moly - in fact DuPont sells a high pressure Krytox which mixes the two. You may hear some horror story from some mechanic about mixing greases and the result turning radioactive or some such. Don't worry, it won't happen with moly or Krytox.

Krytox greases:

* DuPont XHT-AC extra high temperature anti-corrosive Krytox. $30 for a 2oz tube, pn 10195K25; $113 for an 8oz tube, from McMaster Carr.

* DuPont XHT-BDX extra high temperature extra bonding Krytox. $63 for a 2oz tube pn 10195K22; $230 for an 8oz tube pn10195K24 from McMaster Carr.

* LocTite Krytox HyperLube, pn 29711. about $35 for two ounces.

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The grease I use is SuperTech brand Multi Duty Complex Grease (extreme pressure high temperature) from WalMart. It's not a moly disulfide formula. The package states it is composed of high viscosity oils and a complex lithium soap base. It doesn't liquify and it doesn't harden. At twenty nine cents an ounce ($4 for 14 ounces), it compares pretty favorably to the $16 - $31 per ounce stuff - especially since it works really well.

Thanks for the tip on Mobil1. Regular gun oils are too light, but that might just do the trick too. I may experiment with it for comparison purposes at some point.

[xpur3l0g1cx]

SOLUTION: Buy a Saiga .308 Ak and dont look back

[Chuck TX]

Didn't clean it before he shot it? Yikes. I couldn't bring myself to ever do that. My guess would be it was jamming because it wasn't properly cleaned and lubed. I also use Mobile 1.

I have a DPMS .308 (AR-10) with a couple uppers (carbine and 24" bbl). DPMS recommends shooting and cleaning after every shot for the first 25 rounds to break in the barrel for the best accuracy. I don't know how imperative it is, but I did it and all mine are as accurate as any of my bolt actions so it must have worked.

I've never had any jam problems with any type of ammo. One of my long time friends has an Armalite AR-10 and he does have frequent jams, however. Never figured out why.