Side Charging Upper Comparison

[robertg5322]

Wanted a side charging upper for my AR9, and after comparing what was out there, I initially bought a Matrix Arms side charging upper over the NFA. Main differences were the NFA is 6061 aluminum, Matrix is 7075-T6. Probably not a huge deal. Also the NFA has a larger ejection port. And the Matrix Arms charging handle rides on a steel rod, the NFA is a flat plate in a groove on the upper.

Main reasons were the fact that when charging the Matrix Arms, the side charging handle rod did not protrude from the rear. I couldn't tell from the pics on the NFA web site, but it looked as if the bar (it's a steel rod on the Matrix Arms upper, an aluminum plate on the NFA) stuck out the back of the upper when the unit was pulled back.

Matrix Arms website said their unit had the LRBHO feature (it does not when used with Glock mag compliant lowers). That was kind of disappointing, but not a huge deal.

Unit worked well, no issues. But I live in California, and come July, we're limited to 10 round magazines, so I kind of need a LRBHO. So I bit the bullet and bought the NFA unit. 

As I thought, the bar sticks out the rear of the unit when the bolt is racked. Not a huge deal, but I like the clean look of the Matrix Arms unit better. 

So I figure I'll build an Colt magazine compatible upper with the Matrix Arms upper. Ran into an issue; the mags seem too wide for the upper. The upper rear corners of the mag rub against the upper receiver. Anyone know if this is common? The mags go into a RRA magwell block with no issues, but get wedged in the upper. Hate to take a Dremel to it, but may have to.

See pics.

Matrix left side:

New Frontier left side;

 

Close up of NFA slide protruding; 

Edited January 21, 2017 by robertg5322
Added pics.

[robertg5322]

Mag pics, see wear mark at upper rear corner. This is where it rubs the inside of the upper. 

[1tcgc]

I have one that I has the same problem. Last time I had it out I was checking mags dropping free. I had to smack them to seat them and they would not drop. I tried it with just the lower and they went in easily and would drop free. I inserted the mag into the bottom of the upper and they would stick. I tried mags from more than 1 manufacturer. I have not taken the time to take any measurements yet. I do expect to find the opening undersized. I have not contacted NFA about this yet. I wanted to have measurements first.


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[Aircooled6racer]

Hello: I would try some Metalform mags and see if they work better. They seem to have a larger radius on the feed lips and are narrow also. I wish the Matrix upper had a wider slot for the bolt catch but like the look of them. I will try one as soon as I can get my hands on one. Keep us posted on what you find with the Metalform mags. 10 round PCC doesn't sound like fun to me but you will get very good at reloads. Thanks, Eric

[robertg5322]

Thanks for the info Eric.

I'll look for some Metalform mags, those were AR Stoner models, which were reasonably priced, and with the Stoner name, I hoped were good cquality. They're strong, they do not oil-can when you squeeze them, not even a little.

Also going to try them with the NFA upper to see if they're too big for it. They do slide easily into the magwell adapter, so If I have to take a Dremel to the upper or a sander to the mags, I will. 

Oh, one last point of comparison, when I bought the Matrix upper it was $200.00 at joeboboutfitters.com. The NFA is $239.00 anywhere I could find it.

Of the two, I think I prefer the Matrix, too bad it didn't have a LRBHO. Cause you're right, 10 round PCC isn't as much fun as 45 round PCC is.

[Aircooled6racer]

Hello: The AR Stoner mags I tried would not even go into the Hahn insert. They were too wide. I sent them back. I think the AR Stoner/ASC and C-products are all the same mags. The only other one are the Promag. I think for your 10 round limit the 20 round Metalform may be perfect since they will be easier to reload. I may try to find some cheap 10 round Metalforms for bench rest practice or going prone. Thanks, Eric

[bluesman2a]

I'm interested in the solution here as well. I had intended to build a side charging upper that would be using Colt mags.

 

Another side-bar as well, is anybody running modified Uzi mags? I'm running a couple of PCC uppers I've had built for years and the uzi mags work fairly well. The only downside is they don't operate the BHO, but for $7 a piece it's kind of nice to just have a pile of them around. Modding them is pretty simple if you have access to a mill. 

[Aircooled6racer]

Hello: The Metalform 32 round mags can be bought at Palmetto Armory for around $20-$25 when they go on sale. They lock the bolt back perfectly. Thanks, Eric

[bluesman2a]

24 minutes ago, Aircooled6racer said:

Hello: The Metalform 32 round mags can be bought at Palmetto Armory for around $20-$25 when they go on sale. They lock the bolt back perfectly. Thanks, Eric

Good point, currently they are MUCH cheaper than they had been when I built my stash of uzi mags. Back in the day, the colt mags were running in the $40-50 range and nothing else ran well.

[robertg5322]

Update: I squeezed the top of the AR Stoner mags in a vise to make them fit. Then filed the lips parallel. They now seem to work ok. One does not reliably activate the bolt catch, but the feed and cycle well.

 

Midway USA offered to refund my money but since they work, I figure I'll keep thwm. 

 

Both uppers still work well. Either is a good choice, depending on how important LRBHO and magazine choice is to you.

Edited March 14, 2017 by robertg5322

[Aircooled6racer]

Hello: I bought two of the AR Stoner 10 round mags for bench sighting in and they fit perfectly in the Hahn insert and the Quarter Circle 10 lower. They do lock the bolt back as well. The Metalform mags are stronger material but the 10 round mags cost 3 times as much as the AR Stoner ones. I like the looks of the Matrix upper as well. I am using the Quarter Circle 10 Vltor upper and like it with the Raptor charging handle. Thanks, Eric

[JMontie]

Hello: I bought two of the AR Stoner 10 round mags for bench sighting in and they fit perfectly in the Hahn insert and the Quarter Circle 10 lower. They do lock the bolt back as well. The Metalform mags are stronger material but the 10 round mags cost 3 times as much as the AR Stoner ones. I like the looks of the Matrix upper as well. I am using the Quarter Circle 10 Vltor upper and like it with the Raptor charging handle. Thanks, Eric

Here is my issue I have a quarter circle 10 lower. I had a blotter upper with raptor charging handle. Functioned fine. I changed to the matrix side charging and jamming about every 4th or 5th round. Running 147gr @139pf. Ran a few 115gr @ 160pf it ran great. Not sure if it's the upper or the load, will adjust the load and try it again.



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[Aircooled6racer]

Hello: I would try it with some different magazines and see what happens. Could it be rubbing on something slowing the bolt down? Thanks, Eric