AR questions

[sisyphus]

I picked-up a new DSA M4 upper at a gun show early this year and it fits tightly into my Stag lower. I'm having trouble seating mags without a lot of wiggle, and after using the same mags a while I'm getting feed problems. I also have a Bushy 20" heavy upper that has no problems in that area. The distributor salesman says there was a run of Stag lowers that were built out of spec a while back an I might have gotten ahold of one of them. If that were true I'd expect it to have the same problem with any upper, not just the DSA.

Anybody have any input on this? It smells a bit like B.S. to me, but these guys are supposed to be a good outfit to buy from.

[F-16 CHIEF]

Did you build the lower up or was it complete? Either way, I might swap out the mag release. Sounds like that part could be out of spec. Not feeding correctly and loose would all be symptoms of the same piece. Less than 10 bucks so you should be good to go with trying that. I might try Magpul mags and GI mags to see if there's any difference, but I'd really lean towards that mag release.

[sisyphus]

Thanks Chief.

The lower came already built. I thought about the mag release being the problem, but it seems that problem would be there no matter what upper is mounted to the lower, right? It works fine with the Bushmaster upper..........just not with the DSA unit. I might find someone that will let me try their lower with my M4 upper just to see how that fits together.

Have you ever seen a problem with any Stag lowers being built out of spec like this guy told me about? I contacted Stag with the issue and their guy said it was a possibility just like with any manufactured item, but he'd have to see the lower to check it.

The DSA upper shoots real nice when the mags will feed right and it would be great to find a quick fix somewhere rather than sending the thing back. (The only mag problems that happen are with this upper. They all work great with the other one).

[F-16 CHIEF]

How loose is the fit between the upper and lower receivers?

They make an accuwedge that will really tighten that up. I doubt that would cause what you're describing though.

Is your bolt mil spec or some off brand?

Either way, the tightness of the mag should be determined by the lower. The upper should have nothing to do with it.

I don't know all the ends and outs of Stag to know if they've ever had issues.

[sisyphus]

It's very snug. The pins are tight and take a bit of pushing to get them out. The front hings is also pretty tight and you have to use a little pressure to get the upper to rotate upward on the hinge. When I bought the complete upper assembly, the guy told me it was milspec and showed me the mark on the side which indicates that it is(looks like a little embossed keyhole).

What puzzles me is that if it's the lower where this problem originates, how come it works fine with the Bushy 20" heavy barrel upper????

[F-16 CHIEF]

Yeah, that makes no sense.

Try your DSA upper with your Bushy bolt and see if there's a difference. Maybe we can isolate it to one component.

[AKTexas]

http://www.midwayusa.com/viewproduct...pecial80620103

On Sale!

[sisyphus]

http://www.midwayusa.com/viewproduct...pecial80620103

On Sale!

I saw that in their ad earlier. Cheaper than I paid too, but mine has the handle.

Thanks anyway AKT.

[sisyphus]

Yeah, that makes no sense.

Try your DSA upper with your Bushy bolt and see if there's a difference. Maybe we can isolate it to one component.

I never thought of that. Thanks Chief.

[sisyphus]

Neither bolt makes a diff in the DSA either. I tried the lower by itself and every mag clicks home OK. Empty mags do OK with either upper, so the problem is only when they're loaded. (WTH?).

[AKTexas]

I saw that in their ad earlier. Cheaper than I paid too, but mine has the handle.

Thanks anyway AKT.

Yeah I'm kinda miffed about it now since I put down the bills for a complete M4 upper for my daughter.

[F-16 CHIEF]

I'm hurting for answers here.

Maybe that DSA uppper is just out of spec. Check many different mags?

Check the keys on the DSA bolt and make sure they are tightend and it's not hanging down by a hair.

[sisyphus]

I'm stumped too. Wish I was a little more familiar with AR's. I've never had such a finicky piece of hardware except a couple of tube-fed .22's. I might get in contact with the people I got the upper from and see if they can do something.

[abpt1]

I picked-up a new DSA M4 upper at a gun show early this year and it fits tightly into my Stag lower. I'm having trouble seating mags without a lot of wiggle, and after using the same mags a while I'm getting feed problems. I also have a Bushy 20" heavy upper that has no problems in that area. The distributor salesman says there was a run of Stag lowers that were built out of spec a while back an I might have gotten ahold of one of them. If that were true I'd expect it to have the same problem with any upper, not just the DSA.

Anybody have any input on this? It smells a bit like B.S. to me, but these guys are supposed to be a good outfit to buy from.

yes a long time ago stag had some issue since then? I have not heard anything. I stay away from them but Deth has one that works great .. I would sell it and buy another or try and send it back to the mfg.

[Bluedog]

This is perplexing. You have eliminated the lower, the BCG, and magazines. That leaves the upper. Its hard to screw up a machined part, but it sounds to me like the Upper allows the BCG to ride too low and put too much pressure on the feeding rounds. Out of spec uppers are rare, but not unheard of.

The Key hole forge mark means it was forged by Cerro Forge, but that does not tell you who machined it. I have A3 uppers from RRA, DTI, Bushmaster and Spikes, and all are Cerro Forge Keyhole marked.

My guess is that if you are experiencing jams with the first few rounds of a full mag, and the rifle feeds well after the spring pressure is lessened, it's an out of spec upper. It may be out of spec anyway, regardless of what type of jams you are experiencing, because it sounds like you have eliminated all other causes.

I can make just about any military type semi-auto run, but sometimes that requires sending back a bad part. There is no way to fix an out of spec upper.

[TEN-32]

There are two feed ramp cuts. M4 and standard. This may explain a feed issue, but has nothing to do with mag wobble. Here is a thread from another forum with explanation and photos.
http://www.m4carbine.net/showthread.php?t=193

[F-16 CHIEF]

Well, you could always just buy another upper. They're not that expensive.

I switched out my handle upper for a flat top MEGA upper. Only 98 bucks from DDsranch.com

I would check and re-check the bolt, and the keys to make sure.

Check the inside of the upper part of the receiver. Any scoring? Any scoring on the receiver at any points? Check all the parts of the upper and see if anything is rubbing.

[sisyphus]

Well, you could always just buy another upper. They're not that expensive.

I switched out my handle upper for a flat top MEGA upper. Only 98 bucks from DDsranch.com

I would check and re-check the bolt, and the keys to make sure.

Check the inside of the upper part of the receiver. Any scoring? Any scoring on the receiver at any points? Check all the parts of the upper and see if anything is rubbing.

OK Chief. 10-4 and will do but I want to learn a little more than I do right now so I'll know what to look for.,

Thanks again for the advice and help.

[F-16 CHIEF]

One other thing. Do the white grease test.

Use white grease or chalk, or whatever. Mark your mark, fully loaded with it. Then, insert it in the rifle. Take out the mag and see where it's rubbing.

[sisyphus]

One other thing. Do the white grease test.

Use white grease or chalk, or whatever. Mark your mark, fully loaded with it. Then, insert it in the rifle. Take out the mag and see where it's rubbing.

Sorry I didn't answer this one before now. I'll give that method a try. Been busy with a couple of other hardware interests for a couple of weeks but I'll get some white grease if I don't already have it on hand in the plumbing junk pile.

Thanks Chief.