10 Rd RRA mags Failure To Feed in AR180B

[boondock saint]

I'm having a problem with my 10 rd RRA mags feeding in my AR180B.

The 30 rd mag that came with the rifle feeds fine so I figure it is unlikely to be a problem such as the feed ramps or a misaligned gas block, as referred to in the AR180B FAQ.

The rounds are partially stripped out of the mag and stop with the tip just past the top of the feed ramp. If I then pull the bolt back and let it slide forward it feeds the round into the chamber. Pull trigger again, same issue...

It may fire on the first, load the second, jam on the third and forth, fire fifth etc. There does not seem to be any pattern to the problem.

Any suggestions would be appreciated.

 

[Greenhorse six]

Could be the ammo,some times hollow points do that in my ar15,What ammo are you using? mine have been working great in my 180 and ar15,I've only been using 55gr FMJ eagle.
Or maybe its the mag springs.

 

[boondock saint]

The Ammo is American Eagle 55gr FMJ.

I just took apart the mags and measured the springs for length. The shortest spring is 6 5/8 and the longest is 7 1/2 inches. This post http://www.canadiangunnutz.com/forum/showpost.php?p=1455819&postcount=141 shows the new springs to be 5 inches. Could this be the problem?

 

[667]

Armalite at one time advised that some ar15 mags may not function 100% in the 180b... They had a page on their WWW. all abouit it.
The fix was to file down the mag lips a hair... The bolt carrier would rub on the standard lips slowing the bolt enough to f*** up feeding. This explains your partially fed rounds
I had a 180b and some standard ar mags of various manufacture... Some worked fine, others needed to be filed a bit... 'Takes 5 minutes.

 

[Armedsask]

This has been covered in the FAQ. There are a few fixes avaible on top of the one mentioned above.

I've noticed the C Products mags with hollowpoint hate my 180B. Every other mag I've owned functions flawlessly.

 

[KiwiMatt]

The fix was to file down the mag lips a hair... The bolt carrier would rub on the standard lips slowing the bolt enough to f*** up feeding. This explains your partially fed rounds
I had a 180b and some standard ar mags of various manufacture... Some worked fine, others needed to be filed a bit... 'Takes 5 minutes.

This has been covered in the FAQ. There are a few fixes avaible on top of the one mentioned above.

Maybe add this fix to the FAQ

 

[boondock saint]

Thanks 667. I inspected my mags and did find evidence of bolt wear on the mag lip. I then inserted a mag and saw and felt the drag. I am hoping that the bolt dragging on the mag lip, combined with the extra pressure exerted by the longer springs is the problem.
I'll file the mag lips and try it again. If I still have a problem, I'll try shortening the springs a little. Hopefully all goes well.

 

[Armedsask]

Maybe add this fix to the FAQ

Nope, it isn't a required fix.

 

[667]

I am hoping that the bolt dragging on the mag lip, combined with the extra pressure exerted by the longer springs is the problem.

The sping is not the problem.... The bolt carrier does not touch the mag follower... Worry only about those mag lips...

 

[boondock saint]

The sping is not the problem.... The bolt carrier does not touch the mag follower... Worry only about those mag lips...

My thinking was the longer springs might be making it a little harder to drag the round out of the mag as there may be more pressure holding the bullet in the mag, combine that with the drag on the mag lip. Like I said I'll try filing the mag lips first. Thanks again for the tip.

 

[lcq]

My 180B had the same problem until the bolt carrier wore down the mag lips enough for smooth feeding. Now it is slick as goose ####.

Brian

 

[Camp Cook]

So Boondock are your mag's working now?