Jam-o-matic nightmare. UPDATED (thanks)

jcs271

Active member
So I have a .308 10" barrel AR pistol. Has worked fairly reliably using factory Federal Blue Box 150's. The local builder (110 miles away) just changed over the flash hider, tightened the barrel nut and returned it to me. I wanted to get my Eotech sighted in so since I have a bunch of Olin factory 147gr ball I decided to use that. The photos below show what happened on essentially EVERY shot, some were even completely turned aound inside the port. I have a few Ar's but no gunsmithing skills whatsoever. Anybody care to venture a guess on what is going on? Sadly since I am running low on the Federal ammo I did not shoot any of that to see if it behaved the same way. Interestingly, the rounds that do eject literally fly forward at about the "1 o'clock" position. Please offer any thoughts or suggestions. I really hope to not take another road trip
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Originally Posted By: jcs271So I have a .308 10" barrel AR pistol. Has worked fairly reliably using factory Federal Blue Box 150's. The local builder (110 miles away) just changed over the flash hider, tightened the barrel nut and returned it to me. I wanted to get my Eotech sighted in so since I have a bunch of Olin factory 147gr ball I decided to use that. The photos below show what happened on essentially EVERY shot, some were even completely turned aound inside the port. I have a few Ar's but no gunsmithing skills whatsoever. Anybody care to venture a guess on what is going on? Sadly since I am running low on the Federal ammo I did not shoot any of that to see if it behaved the same way. Interestingly, the rounds that do eject literally fly forward at about the "1 o'clock" position. Please offer any thoughts or suggestions. I really hope to not take another road trip
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Easy, your ball ammo is too light to make it cycle completely. Use some factory hunting ammo or use a lighter buffer spring and I bet your problem goes away.
 
In my experience the large frame ARs benefit GREATLY from an adjustable gas block. The best $25 bucks I ever spent on those rifles. I'd bet ya money that it would fix your problems.
 
Did you try loading 1 round, and seeing if the bolt locks back after firing? Usually I think brass landing at 1:00 means overgassed.
 
GREAT NEWS! I got home this evening, went down to the basement stash and found 13 boxes of long forgotten 168gr Federal Match (I really need to get organized). Anyway, loaded up a 20rd mag and it was bang, bang, bang till I ran it dry! Thanks for the input, and I may look into an adjustable gas block.
 
20 round mag. until it ran dry?
Well, that`s great news, but I suggest saving that brass..reloading is sooo much more economical.
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Originally Posted By: jcs271I may look into an adjustable gas block.

If your rifle is short stroking due to lower powered ammo, an adjustable gas block will do you no good
 
Quote: an adjustable gas block will do you no good...Correct..The adjustable gas block will only help if you are shooting over powered ammo as it will let you retard the cycling...

Since it is a 'pistol', is it possible that you were 'limp wristing' a little with that military ball?? That would cause the action to short stroke as well...That ammo, while good in a 'battle rifle', seldom comes close to performance of modern factory ammo for the civilian market..
 
Originally Posted By: MGYSGTOT. "limp wristng". Harsh, very harsh.

Thanks for the support sarge. One of the peculiar rulings coming out of ATF recently was the ability to create a quite useful "pistol" out of an AR. No worry about limp wristing this one. I have several (and an AK version) but this one is a favorite. Kind of the ultimate house gun. When I go out at night to see what is upsetting my animals I am pretty well set up to deal with a wayward bear or a disgruntled "customer" who disagreed with one of my decisions. It normally wears an M3 light on the top rail which can be activated by my fingertips while holding the rifle in a shooting position. Twenty seven inches of .308 fun!



P.S. To answers Steves question about why I have one. BECAUSE I CAN!
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Originally Posted By: Widow maker 223I dont see why limp wristing will cause short stroking when that yas zero to do with the gas system.

Even though it is gas operated, there IS some inertia involved to some degree.
 
True there is a little, but this is not a light recoiling weapon nor is the gun heavy. It should have more recoil than a rifle length .308. This is clearly caused by the ammo.
 
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