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ritterbruder
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Posted: 3/27/2012 3:17:59 AM

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I was at the range the other day shooting my AR which I had just cleaned. I shot about 200 rounds of Wolf before shooting M855. The Wolf ran flawlessly, but when I switched to M855, I had like 8 jams out of 10 rounds. It was crazy. All of them were failures to feed. The round would basically get stuck on the feed ramp. After that, I just called it a day and went home to clean my gun thoroughly.

I've shot almost 1500 rounds of Wolf through my gun with zero malfunctions. Does anyone know what might have happened with the M855?
Gamma762
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Posted: 3/27/2012 3:35:16 AM
[Last Edit: 3/27/2012 3:36:02 AM by Gamma762]
There's a known common issue with shooting brass cased after steel, but it manifests itself as extraction or sometimes chambering troubles. If your M855 wasn't making it past the feed ramp then something else is going on... as a SWAG I'd think magazine first.

Did you try going back to steel to see if it worked?

More details about the rifle configuration might be helpful.
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ritterbruder
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Posted: 3/27/2012 5:13:56 PM
I've heard about the same issue too where the expanding brass cases will stick in a chamber that has been gunked up by steel-cased ammo. I'm positive I didn't have any issues with stuck cases. One thing I did afterwards was to fire single-shots of M855 by port-loading. No malfunctions then, so maybe it is a magazine issue.

The magazine I used was a 20-round PMag. That particular magazine was kept loaded with 20-rounds of TAP for home-defense (and yes, I used the top cover). I unloaded it prior to going to the range and that was my first time shooting that particular magazine. Do you think keeping the magazine loaded caused the spring to get weak? I know it's debated but I think the general consensus is that it's okay to do that.

My AR is a 16" Spike's that I assembled, carbine-length gas system.

chewbacca
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Posted: 3/27/2012 5:26:02 PM
[Last Edit: 3/27/2012 9:53:03 PM by chewbacca]
Are you using a standard carbine buffer? What configuration is your AR, rifle, carbine, midlength...?

Did you try another mag?

Did you try shooting the wolf again after the brass?
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Gatorhunt
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Posted: 3/27/2012 5:36:35 PM
I don't think keeping the mag loaded would hurt anything, springs don't wear out like that, they wear out from being compressed and uncompressed over and over.

That said, I have heard of some people having issues with those 20 rounders before, I would try some other mags.
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Blankwaffe98
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Posted: 3/27/2012 5:55:20 PM
Originally Posted By ritterbruder:
I've heard about the same issue too where the expanding brass cases will stick in a chamber that has been gunked up by steel-cased ammo. I'm positive I didn't have any issues with stuck cases. One thing I did afterwards was to fire single-shots of M855 by port-loading. No malfunctions then, so maybe it is a magazine issue.

The magazine I used was a 20-round PMag. That particular magazine was kept loaded with 20-rounds of TAP for home-defense (and yes, I used the top cover). I unloaded it prior to going to the range and that was my first time shooting that particular magazine. Do you think keeping the magazine loaded caused the spring to get weak? I know it's debated but I think the general consensus is that it's okay to do that.

My AR is a 16" Spike's that I assembled, carbine-length gas system.



Cases could have been sticking enough to cause the rifle to border on short stroking causing the return stroke of the BCG on battery stroke to be short/slower.

The reason that shooting steel and then brass causes issues is the fact the steel cases do not expand like brass.This lack of expansion in the steel cases causes less seal between the case and the chamber walls,ultimately causing more blowby and fouling build up.

Once the brass is fired in this chamber condition its effectively fire forming to the uneven carbon build up which undersized the chamber,especially in the shoulder/neck/throat.
Best advice is to shoot brass before steel,and if absolutely possible clean the chamber with a chamber brush and CLP before switching between the two different types of cases/ammo.
458winmag
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Posted: 3/27/2012 8:57:30 PM
Originally Posted By Blankwaffe98:
Originally Posted By ritterbruder:
I've heard about the same issue too where the expanding brass cases will stick in a chamber that has been gunked up by steel-cased ammo. I'm positive I didn't have any issues with stuck cases. One thing I did afterwards was to fire single-shots of M855 by port-loading. No malfunctions then, so maybe it is a magazine issue.

The magazine I used was a 20-round PMag. That particular magazine was kept loaded with 20-rounds of TAP for home-defense (and yes, I used the top cover). I unloaded it prior to going to the range and that was my first time shooting that particular magazine. Do you think keeping the magazine loaded caused the spring to get weak? I know it's debated but I think the general consensus is that it's okay to do that.

My AR is a 16" Spike's that I assembled, carbine-length gas system.



Cases could have been sticking enough to cause the rifle to border on short stroking causing the return stroke of the BCG on battery stroke to be short/slower.

The reason that shooting steel and then brass causes issues is the fact the steel cases do not expand like brass.This lack of expansion in the steel cases causes less seal between the case and the chamber walls,ultimately causing more blowby and fouling build up.

Once the brass is fired in this chamber condition its effectively fire forming to the uneven carbon build up which undersized the chamber,especially in the shoulder/neck/throat.
Best advice is to shoot brass before steel,and if absolutely possible clean the chamber with a chamber brush and CLP before switching between the two different types of cases/ammo.


Damn.
Finally a reasonable answer as to 'why ?'
urbanpi
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Posted: 3/27/2012 11:28:23 PM

Originally Posted By Blankwaffe98:
Originally Posted By ritterbruder:
I've heard about the same issue too where the expanding brass cases will stick in a chamber that has been gunked up by steel-cased ammo. I'm positive I didn't have any issues with stuck cases. One thing I did afterwards was to fire single-shots of M855 by port-loading. No malfunctions then, so maybe it is a magazine issue.

The magazine I used was a 20-round PMag. That particular magazine was kept loaded with 20-rounds of TAP for home-defense (and yes, I used the top cover). I unloaded it prior to going to the range and that was my first time shooting that particular magazine. Do you think keeping the magazine loaded caused the spring to get weak? I know it's debated but I think the general consensus is that it's okay to do that.

My AR is a 16" Spike's that I assembled, carbine-length gas system.



Cases could have been sticking enough to cause the rifle to border on short stroking causing the return stroke of the BCG on battery stroke to be short/slower.

The reason that shooting steel and then brass causes issues is the fact the steel cases do not expand like brass.This lack of expansion in the steel cases causes less seal between the case and the chamber walls,ultimately causing more blowby and fouling build up.

Once the brass is fired in this chamber condition its effectively fire forming to the uneven carbon build up which undersized the chamber,especially in the shoulder/neck/throat.
Best advice is to shoot brass before steel,and if absolutely possible clean the chamber with a chamber brush and CLP before switching between the two different types of cases/ammo.

I'll only add to this that the steel ammo is usually .223, and OP did exactly what I did when this happened, I switched from steel .223 over to Gov't contract 5.56 FMJ. I had my first stuck case in about 800 rounds. The tighter fit of the 5.56 becomes more apparent when chamber is fouled.
ritterbruder
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Posted: 3/28/2012 12:02:38 AM
Originally Posted By Blankwaffe98:
Originally Posted By ritterbruder:
I've heard about the same issue too where the expanding brass cases will stick in a chamber that has been gunked up by steel-cased ammo. I'm positive I didn't have any issues with stuck cases. One thing I did afterwards was to fire single-shots of M855 by port-loading. No malfunctions then, so maybe it is a magazine issue.

The magazine I used was a 20-round PMag. That particular magazine was kept loaded with 20-rounds of TAP for home-defense (and yes, I used the top cover). I unloaded it prior to going to the range and that was my first time shooting that particular magazine. Do you think keeping the magazine loaded caused the spring to get weak? I know it's debated but I think the general consensus is that it's okay to do that.

My AR is a 16" Spike's that I assembled, carbine-length gas system.



Cases could have been sticking enough to cause the rifle to border on short stroking causing the return stroke of the BCG on battery stroke to be short/slower.

The reason that shooting steel and then brass causes issues is the fact the steel cases do not expand like brass.This lack of expansion in the steel cases causes less seal between the case and the chamber walls,ultimately causing more blowby and fouling build up.

Once the brass is fired in this chamber condition its effectively fire forming to the uneven carbon build up which undersized the chamber,especially in the shoulder/neck/throat.
Best advice is to shoot brass before steel,and if absolutely possible clean the chamber with a chamber brush and CLP before switching between the two different types of cases/ammo.


It wasn't apparent to me that the cases were sticking since they ejected fine, but that makes a lot of sense to me since a stuck case could throw the timing off
Gamma762
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Posted: 3/28/2012 12:54:52 AM
Again, if they weren't getting past the feedramp/barrel extension, the chamber fouling isn't the problem.

You might have a cyclic rate issue with the higher power ammo manifesting itself as feeding issues. Heavier buffer might help if you had one to test. PMag 20s are also not an "anti tilt" magazine, they can't be because of the nature of a straight magazine, so I'd also try some alternative magazines if available.
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RGIFFOUR
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Posted: 3/28/2012 4:55:31 PM
[Last Edit: 3/28/2012 4:57:02 PM by RGIFFOUR]
I do brass then steel.. never steel than brass..

and if I did.. I'd do only enough steel cased ammo to empty the mag so I could load brass..

I did a session of steel than brass and back and forth.. but that was after 800+ rounds of both thru the chamber and the rifle was broke in..

I agree the blow-by from the steel 1st is more than likely gunking up the chamber.. then you try brass and get your issues..

Run the 855 1st.. then try the steel.. should be GTG then..

**Keep in mind I too run mainly Wolf WPA (mil-classic) in both my AR's as its cheaper than brass currently..
chewbacca
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Posted: 3/28/2012 6:52:29 PM
Originally Posted By Gamma762:
Again, if they weren't getting past the feedramp/barrel extension, the chamber fouling isn't the problem.

You might have a cyclic rate issue with the higher power ammo manifesting itself as feeding issues. Heavier buffer might help if you had one to test. PMag 20s are also not an "anti tilt" magazine, they can't be because of the nature of a straight magazine, so I'd also try some alternative magazines if available.


Exactly. That's why I originally asked what buffer weight, but then edited that because we don't even know the configuration of his rifle.
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