first time taking AR out . Jamming issues, Advice ?

Kondor

Kondor

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I finally got to take my new to me used Nea 7.5" Ar15 chambered in 5.56.

I had several jams. I was using PPu 5.56 brass case ammo.

The gun would fail to extract thankfully a spent round and tried to chamber a live one and would jam the projectile into the cartridge costing me ammo aswell

upon talking with the previous owner he experienced similar situation using 5.56 but .223 worked

I am going to buy some .223 and sell my remaining 5.56 but before i do just checking to see other people's thoughts

mine is that the 5.56 has too much pressure for the 7.5" Barrel ? and .223 should fix this ?

or is there somthing potentially wrong with the extractor or lacking proper lubrication ?

Thanks for your input !
 
Lube it well they like to run wet. I had the same problem and I put some oil on top of the first round in the mag and ran it. This cleared up my problem. Good luck.
 
Any damage to the rim of the spent cases? Could be undergassed from a misaligned or loose gas block, could be dull/weak extractor, could be bad magazines, could be too heavy a buffer or buffer spring or a combination of a few of them. The ammo with the bullets pushed into the case, could be a result of the spent case still being present.
 
Before you start selling stuff or swapping parts check the simple things...

1) properly lubed?
2j Magazines...specific mag or different brands / types?
3) Ammo...try a couple different brands (and some .223)

Once those are eliminated you can start with the bigger stuff...extractor, gas system, buffer, etc. But my bet is that one of the first 3 is the culprit.
 
Make sure it has a carbine length buffer spring. I had a similar problem with a 14.5 length barrel. Shortened the spring by 2 coils. Works fine now.
 
GunCrazy762 said:
Lube it well they like to run wet. I had the same problem and I put some oil on top of the first round in the mag and ran it. This cleared up my problem. Good luck.
Click to expand...

This is not a lube issue.

Trinimon said:
Any damage to the rim of the spent cases? Could be undergassed from a misaligned or loose gas block, could be dull/weak extractor, could be bad magazines, could be too heavy a buffer or buffer spring or a combination of a few of them. The ammo with the bullets pushed into the case, could be a result of the spent case still being present.
Click to expand...

There is no way a 7.5" AR is undergassed, port pressure is over 48K PSI and a stock 20" AR has a port pressure of around 20K PSI. The OP's rifle is quite the opposite and is grossly over gassed. The bolt is cycling as it's creating a double feed. If the spent case is still in the chamber then I guarantee there are slip marks from the extractor coming off due to premature extraction. There's a good chance the primers are very flat or even slightly proud(dislodged) from the case.

Innavedaw said:
Before you start selling stuff or swapping parts check the simple things...

1) properly lubed?
2j Magazines...specific mag or different brands / types?
3) Ammo...try a couple different brands (and some .223)

Once those are eliminated you can start with the bigger stuff...extractor, gas system, buffer, etc. But my bet is that one of the first 3 is the culprit.
Click to expand...

1. Not a lube issue
2. Magazines have NOTHING to do with this issue
3. True 5.56 spec ammo will produce a significant increase in pressures which aren't helping.

palwait said:
Make sure it has a carbine length buffer spring. I had a similar problem with a 14.5 length barrel. Shortened the spring by 2 coils. Works fine now.
Click to expand...

If you're clipping springs then your gun is a lemon. If you're clipping springs then you don't understand what the problem above is as reducing spring pressure is the wrong answer.

OP,

I'm betting your ultra short AR has a standard 0.060"-0.075" gas port which is way way too big for such a short barrel. With an ultra short gas tube you are again adding to the problem by reducing volume and thus shortening the time it takes the gas to reach the BCG and attempt to unlock the action. Your rifle is getting too much gas and trying to cycle before the chamber pressure has dropped to a safe level and a level where the brass can contract enough for propper extraction. The extractor is either failing(jumping the rim) due to the high pressure or it is damaging the rim(s)(gouging or tearing) of the spent case during it's rearward travel. The fact your rifle is then feeding another live round creating a double feed is indicative of a rifle that is not under gassed but grossly over gassed.

Solutions: Heavier recoil spring and/or a heavier buffer. Feeding it lower pressure .223rem ammo will help as well. There's nothing you can do about the gas port size unfortunately, short of changing the barrel.
 
Kidd X said:
This is not a lube issue.



There is no way a 7.5" AR is undergassed, port pressure is over 48K PSI and a stock 20" AR has a port pressure of around 20K PSI. The OP's rifle is quite the opposite and is grossly over gassed. The bolt is cycling as it's creating a double feed. If the spent case is still in the chamber then I guarantee there are slip marks from the extractor coming off due to premature extraction. There's a good chance the primers are very flat or even slightly proud(dislodged) from the case.



1. Not a lube issue
2. Magazines have NOTHING to do with this issue
3. True 5.56 spec ammo will produce a significant increase in pressures which aren't helping.



If you're clipping springs then your gun is a lemon. If you're clipping springs then you don't understand what the problem above is as reducing spring pressure is the wrong answer.

OP,

I'm betting your ultra short AR has a standard 0.060"-0.075" gas port which is way way too big for such a short barrel. With an ultra short gas tube you are again adding to the problem by reducing volume and thus shortening the time it takes the gas to reach the BCG and attempt to unlock the action. Your rifle is getting too much gas and trying to cycle before the chamber pressure has dropped to a safe level and a level where the brass can contract enough for propper extraction. The extractor is either failing(jumping the rim) due to the high pressure or it is damaging the rim(s)(gouging or tearing) of the spent case during it's rearward travel. The fact your rifle is then feeding another live round creating a double feed is indicative of a rifle that is not under gassed but grossly over gassed.

Solutions: Heavier recoil spring and/or a heavier buffer. Feeding it lower pressure .223rem ammo will help as well. There's nothing you can do about the gas port size unfortunately, short of changing the barrel.
Click to expand...

^This, with one comment: Adjustable gas block works wonders for short ARs, once tuned in.
 
Thank you Kidd, Nice response ! Definitely plan on trying some .223 once i can afford to pick some up! Bought too much 5.56 lol

and definitely will look into an adjustable gas block1
 
Kjm1971 said:
^This, with one comment: Adjustable gas block works wonders for short ARs, once tuned in.
Click to expand...
Good point, I'm not a fan but it would provide more options for tuning an ultra short gas system.

Kondor said:
Thank you Kidd, Nice response ! Definitely plan on trying some .223 once i can afford to pick some up! Bought too much 5.56 lol

and definitely will look into an adjustable gas block1
Click to expand...

Hope the info helps.
 
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I had the exact problem with mine. I bought a pigtail gas tube from True North Arms and it worked great after that.
 
Kidd X said:
This is not a lube issue.



There is no way a 7.5" AR is undergassed, port pressure is over 48K PSI and a stock 20" AR has a port pressure of around 20K PSI. The OP's rifle is quite the opposite and is grossly over gassed. The bolt is cycling as it's creating a double feed. If the spent case is still in the chamber then I guarantee there are slip marks from the extractor coming off due to premature extraction. There's a good chance the primers are very flat or even slightly proud(dislodged) from the case.



1. Not a lube issue
2. Magazines have NOTHING to do with this issue
3. True 5.56 spec ammo will produce a significant increase in pressures which aren't helping.



If you're clipping springs then your gun is a lemon. If you're clipping springs then you don't understand what the problem above is as reducing spring pressure is the wrong answer.

OP,

I'm betting your ultra short AR has a standard 0.060"-0.075" gas port which is way way too big for such a short barrel. With an ultra short gas tube you are again adding to the problem by reducing volume and thus shortening the time it takes the gas to reach the BCG and attempt to unlock the action. Your rifle is getting too much gas and trying to cycle before the chamber pressure has dropped to a safe level and a level where the brass can contract enough for propper extraction. The extractor is either failing(jumping the rim) due to the high pressure or it is damaging the rim(s)(gouging or tearing) of the spent case during it's rearward travel. The fact your rifle is then feeding another live round creating a double feed is indicative of a rifle that is not under gassed but grossly over gassed.

Solutions: Heavier recoil spring and/or a heavier buffer. Feeding it lower pressure .223rem ammo will help as well. There's nothing you can do about the gas port size unfortunately, short of changing the barrel.
Click to expand...

^^^ this ^^^
 
lavino said:
I am kinda new to AR too so plz forgive me if I am not making sense ;) I heard some people suggested switching to a slightly heavier buffer in case of overgas situation. Would this be another viable approach too or is there any advantages or disadvantages to this?
Click to expand...

A heavier buffer, heavier spring or heavier buffer and spring all work to keep the action closed longer, so that pressures drop and cases contract before the BCG tries to extract and cycle. A heavier buffer or spring in a longer barreled rifle isn't unusual either and for the same reasons. I personally run T2 buffers in my AR's from 11.5" to 16". Gives a very smooth feeling action when it cycles.

The goal is to try and achieve the same "cycling" energy as the classic 20" rifle length gas system guns. The old traditional has a comparatively low port pressure of about 19K PSI which is why the 20" guns cycle very smooth and don't have an aggressive recoil impulse. The added weight and length also helps but we're talking gas systems here. The shorter carbine gas system of the M4 is a compromise and was partially designed to be gassed as a reliability feature. The M4 or any carbine gas AR is still over gassed(33K PSI), just not as much as some of the shorter guns like 11.5"/10.5"/and shorter(depending on maker the gas ports on the short guns can be crazy large causing insane pressures). Add in the gas port variances between manufacturers and pressure differences between ammo(5.56 vs .223) and you can end up with a very over gassed gun or an under gassed gun. Both of which won't run properly. The mid length gas system was introduced as a mechanical(and fixed) method of trying to achieve the golden 20" AR "cycling" energy/pressures. With a 14.5" or 16" barrel there's no need to have the gas port so far back from the muzzle. Moving the port forward reduces dwell time, the time in which the BCG is receiving gas pressure before the bullet exits the barrel and breaks the seal. By reducing dwell time you are also reducing PSI. We know that the carbine gas system is already over gassed. So we can play with the amount of gas and the amount of time the BCG gets that gas in an attempt to find that "low" pressure sweet spot that still provides reliable cycling without beating the life out of the gun or shooter.

There are manufacturers who offer a mid length gas system on barrels as short as 12.5". That puts the gas port less than two inches from the muzzle! In such a case the gas port would be enlarged to allow a rapid and high volume flow of gas over a very short period of time to ensure reliable cycling(short dwell time) as the bullet has almost left the barrel breaking the seal and eliminating all gas pressure. Again there is a sweet spot between gas system length, barrel length, and gas port size. Here's the easy and reliable route/numbers, some barrel lengths are workable with two gas system lengths.

18" and up- Rifle length gas system
18"-14.5" Midlength gas system
14.5"-10.5" carbine gas system
Under 10.5" Pistol length gas system(if the gun is tuned and built properly)
 
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Kidd X said:
This is not a lube issue.



There is no way a 7.5" AR is undergassed, port pressure is over 48K PSI and a stock 20" AR has a port pressure of around 20K PSI. The OP's rifle is quite the opposite and is grossly over gassed. The bolt is cycling as it's creating a double feed. If the spent case is still in the chamber then I guarantee there are slip marks from the extractor coming off due to premature extraction. There's a good chance the primers are very flat or even slightly proud(dislodged) from the case.



1. Not a lube issue
2. Magazines have NOTHING to do with this issue
3. True 5.56 spec ammo will produce a significant increase in pressures which aren't helping.



If you're clipping springs then your gun is a lemon. If you're clipping springs then you don't understand what the problem above is as reducing spring pressure is the wrong answer.

OP,

I'm betting your ultra short AR has a standard 0.060"-0.075" gas port which is way way too big for such a short barrel. With an ultra short gas tube you are again adding to the problem by reducing volume and thus shortening the time it takes the gas to reach the BCG and attempt to unlock the action. Your rifle is getting too much gas and trying to cycle before the chamber pressure has dropped to a safe level and a level where the brass can contract enough for propper extraction. The extractor is either failing(jumping the rim) due to the high pressure or it is damaging the rim(s)(gouging or tearing) of the spent case during it's rearward travel. The fact your rifle is then feeding another live round creating a double feed is indicative of a rifle that is not under gassed but grossly over gassed.

Solutions: Heavier recoil spring and/or a heavier buffer. Feeding it lower pressure .223rem ammo will help as well. There's nothing you can do about the gas port size unfortunately, short of changing the barrel.
Click to expand...
An adjustable gas block can help but I would start with an H3 buffer.
 
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