AR-15 short stroking? (Or just not working)

Lol I'm putting a guess that with your avatar image that you were in the Air Force? Did you never do basic weapons training? Only use rifle oil for rifles lol or grease, especially in cold conditions. Using engine oil on your rifle probably won't help at all in cold conditions. It's not destined for rifles lol.

Hope it all works out!

:cheers:
 
I had the same issue with the AE black box 55gr. I switched to another quality brand name and the problem went away. Even MFS would work in the gun but not the black box 55gr.

No issues with the black box in any other guns though just the AR's.
 
alberta tactical rifle said:
Leave the 5w30 in your engine where it is meant to be and use a GUN specific product like G96 spray lube which will NOT freeze or even thicken unless it is 100 below.

Why is that guys always want to use products designed for a car in a gun? Good thing women cook.
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Because "GUN LUBE" is a money grab and total BS. I have been running a combination of Lucas High Temp Wheel bearing Grease and Mobli1 5w20 synthetic on every gun I own for the past 5 years in +40c to -40c with ZERO malfunctions in tens of thousands of rounds. I'm at 12 225 .223 in my Colt Comp HBAR this year with zero malfunctions. Gun oil is total BS. It's the same thing rebottled and sold for 10x the price.
 
Could the buffer spring be too stiff or the buffer weight not right for the type of ammo being used? I read on the Sig forum about Sig AR owners having short stroking issues with off the shelf .223 ammo and the gun worked when shooting higher pressure 556. One guy went as far as cutting an inch off his buffer spring and the problem went away. I'm no gunsmith but I read that on the internet so it's gotta be true... :)
 
Could the buffer spring be too stiff or the buffer weight not right for the type of ammo being used?
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Unlikely. There is only one buffer/spring for an A2 stock (well, that's not entirely true but true enough for this scenario)

One guy went as far as cutting an inch off his buffer spring and the problem went away.
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Don't cut springs. Besides, it's not that 'the problem went away', it just 'cured' the symptom of the main problem.

op - check that your gas key is tight, if it is, remove your gas block and check the gas port diameter. There is a chart on arfcom that has the various sizes for ports according to barrel length and journal diameter. Make sure yours falls in the correct range.
 
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Well, in order to hopefully diagnose the issue, here are the main parts of the build.

ARTS 20" stainless barrel
Armalite clamp on front sight, A2 style
DPMS Titanium nitride BCG
Armalite A2 stockset

That should be everything involved with the cycling.

Unfortunatly, I wont be able to hit the range anytime soon, so this issue won't be resolved for a few months.
 
My friend recently bought a 20" ATRS barrel and it had a slightly undersize gas port. So now I'm definitely leaning towards that being the issue with yours.

lol, I had a hunch that's who made your barrel ;)

He sent them his whole upper and they opened his gas port and now it works fine.

If you are capable you can open it yourself, but seeing as it's a new barrel, I'd let the manufacturer fix it.
 
Stainless and Tit.nit. carries are heavy and require ammo with some b@lls to cycle properly. Try some surplus mil. spec ammo and your problem may go away.
I have even seen piston guns stumble with some less snappy ammo.
 
Ill try some other ammo before I start looking at rifle components. I heard Sellier and Bellot as well as Privi is good ammo and a bit hotter then North American loads.
 
I have found PPU .223 (headstamped 5.56) to be wicked hot. I get 5.56 velocities with it and you (I) can feel the extra jam.

Not sure about S&B

To be honest, your gun should run AE no problem. If it couldn't run MFG or Remington UMC, I'd say "enh, ok *shrugs*", but AE is 'hot' enough that you shouldn't have short stroking issues with it. Especially out of a 20" barrel.

Now, if it works with PPU or S&B and you're fine with only running hotter ammo, then who am I to argue? But you should at least check the port size. If your gas block is a clamp-on, it shouldn't take you more than 5 minutes.
 
This chart may help, courtesy of AR15.com:


Barrel Length (in) Barrel Diameter (in) Distance from Muzzle (in) Min Port Size (in) Max Port Size (in)
11.5 .625 3.850 .081 .089
11.5 .750 3.850 .086 .094
14.5 .625 8.375 .063 .078
14.5 .750 8.375 .070 .086
16 .625 8.375 .063 .078
16 .750 8.375 .070 .086
20 .625 6.875 .086 .093
20 .750 6.875 .093 .096
24 .825 N/A .089 .089
 
.086 is on the low end of the 20" barrel with rifle gas system spectrum, IIRC the M16 port is .091 +.001 (allowable tolerance range).

The TiN bolt carrier group should have a better coefficient of friction that the MagPhospated carrier - so that I would rule that out. However check the bolt carrier and gas key area - ensure their is not bleeding of gasses - specifically at the front 'open' area. AR's are pretty tolerant to minor gas leaks at the block and gas tube (relatively) but the gas key is a deadliner. Speaking of gas leaks -- clamp blocks generally suck ass, as they don't seal well around the barrel at the gas port area.

And despite Heckler's comments to the contrary - piston guns are actually more ammo sensitive - which is why most have gas regulators...
 
Your absolutly correct Kevin...Poor wording on my part.
what I was eluding to was they can be tempermental
I have seen where you need to adjust several times per range sesion with different types of ammo being tested/used. Even Temp. differences can sometimes require some adjustments to be made.
But you know all of this.....you are a valuable source of info on AR's
Once dialed in though....happy shooting
 
What is Rick's spec?

The M16 is overgassed, it does not need that much to function with M193 or M855, it was done that way for a variety of reasons including proper function in different environments and clean/dirty etc.

While not ATRS, I will give you my thoughts
Our (KAC/KMC) first SR-15's where what some feel as undergassed. The gun was designed in FL, and ran fine with M855 even in cold testing. What happened was folks ran weak ammo in the cold (the original SR-15 gas port was opened up a few thou after complaints about errative function with .223Rem ammo).
I prefer a gun not to be overgassed, I loved the early SR-15 as it was smooth as silk --- however I live in Fl and lube my weapon.
I shot a bunch of guns sent in -- with Wolff (about the weakest ammo available) and cold soaked a few with no major issues -- I did need to lube a few, and in one case needed to replace a carrier key upon inspection that it was leaking.

However the decision above my paygrade was made to open the port up to allow folks to take their $2300 rifle and shoot garbage ammo thru it.

The other aspect on this, is regardless of what ATRS's ammo spec is, its a parts gun, and I would say that you have an ammo issue, or a gas leak. That's my personal feeling.

Reaming a gas port is easy anyway - it would probably be cheaper to buy an 0.090 and 0.092 Reamer from MSC Direct and do it yourself.
 
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