Sunday, December 11, 2011

Tuning 5.45mm AR-15 Mags

So far, every C Products and ASC 5.45mm magazine that I've tried has caused jams, straight out of the packaging.  Every one.  Things are okay if I don’t load more than about a dozen rounds, but when I load 20 or 25, I’ll get plenty of stoppages.  Whenever I remember to check, the stoppages have all come when feeding from the right side of the magazine.

This is the typical 5.45mm feed jam. Looks like bolt-over-base.

If you load 5 or 6 rounds (look at both feed lips), you’ll see that the feed lips are holding the case along the full length.  When you get to around 20 rounds in the magazine, you’ll start to see that the lips of the magazine are really only holding the case near the rim.  The left-side feed lips are usually pretty good, but the right-side feed lips have all left the front end of the cases of the rounds without much support.  There seemed to be a logical connection.

You need to be prepared to finish manufacturing the magazine tubes.  In a somewhat rare fashion, I decided that this particular job was better to handle with some finesse, rather than brute force.  Another Spike’s 5.45mm upper owner said he fixed the magazines with a hammer.  I decided to make another magazine lip tool, and I bend the feedlips. . . carefully.  At first, I was just bending the lips to hold the cases of the rounds better when loaded to capacity.  This resulted in about a 50% success rate.  Some of the newly tuned magazines ran fine.  Some still jammed as if I hadn’t done anything.  Some of the magazines would feed up until the 2nd to last round, and then jam.

The problem seems to be related to the angle that the bullets were presented.  With the magazines that worked, the tips of the bullets were only a few millimeters above the front edge of the magazine.  The ones that continued to jam, as if I hadn’t done anything, had the bullets sitting higher.  The ones that didn’t jam until the 2nd to last round, I had bent the feed lips too far, and the tip of the bullet was almost even with the front edge of the magazine.

The modified magazines hold the 5.45mm ammo at the same angle as my D&H aluminum U.S.G.I.-type 5.56mm magazines.  Yeah, I guess maybe I should have checked this earlier.

See how the tip of the bullet in the unmodified mag points skyward.  "There's your problem!"

New strategy.  Take one of the magazines that works, and fix the others to match it.  This seems to be working well.  I think maybe I got this figured out.


Anonymous said...

Are those mags extremely cheap or free?

If not why would you mess around when pmags are available for $11/ea when on sale?

It's still good to make use of material on hand, but I couldn't recommend something that was shipped with that functionality.

Suburban said...

There aren't any 5.45x39mm PMags. There's only one company making 5.45mm AR mags, and they're hit or miss (although all the one's I've gotten have needed work).

5.45mm is the AK-74 round. 5.56mm/.223Remington is what the PMags are made for.

Will I buy another 5.45mm C Products/ASC/AR Stoner mags? I'm not sure.

Anonymous said...

This is the same problem the .308 ar's have. The c-products mags present the bullets too low and as you can see on comparison the pmags are higher in the front. The followers are indicted as well.

Clay said...

I noticed the same issues when I was at the range yesterday with my factory built S&W M&P15r.

The mags for this thing are really leaving a sour taste in my mouth. I really wish someone (Hello Magpul!?) would come out with a pmag follower, or a new mag all together, that would work with 5.45. I would invest heavily!

Anonymous said...

anybody try swapping 5.45 follower into pmag yet? was gonna give it a shot after numerous dbbl feeds lately.

Herk North said...

Following your advice, I bought the Brownells tool and tuned my ASC magazines' feed lips. I took them all out shooting last week and found that all but one of them fed flawlessly, which is by far the best performance that I've yet had with these magazines.

What I found later on was that the angle of presentation of the rounds started "rising" after this outing. Have you found that the feed lips started relaxing or otherwise changing after you tuned them?

I also still need to try some AK74 springs in my magazines.

Thanks for putting this information out there!

Suburban said...

Have not had any problems with magazines reverting to their original state, but perhaps they have changed the material that the magazine tubes are made of. It's been a few years since the last time I bought a 5.45mm AR magazine.