Magazine questions

[bubbas4570]

I picked up a couple of used mags from a LGS. The 308AR mag is a DPMS metal mag, I assume from the stamping on the baseplate. And my question, any answers as to why it doesn't lock in without the bolt being locked back AND ejects upon the bolt riding forward. It feed correctly with A-zoom dummies.  I have ZERO problems with Magpul mags in this receiver, and have never tried anything else,  just to give past info.

Do DPMS mags need some fitting to work once in a while? Or is this a mutt?

 

[bubbas4570]

And I also have questions on a AR15 mag for ID purposes,  if this works here also. Unless I need to go to the black rifle section for that.

[bubbas4570]

And FWIW, the mag does not lock into place. I can pull it out, but it does not fall out.

 

Early generation APF receiver. And they used to make parts for DPMS......

3 digit serial number receiver.

[washguy]

Sometimes you get mutts as you stated....tolerences on these suk sometimes....sometimes they can be fixed...and then again sometimes not  .....Wash

[bubbas4570]

Cool. I am not against doing a bit of filing on the mag latch hole if that fixes it.

[bubbas4570]

$15 .....makes for a worthwhile challenge then.

[Sisco]

Old DPMS mags did not have a great reputation if I remember correctly.

[98Z5V]

bubba, can you lock that mag into place with the bolt locked to the rear?  LOCK it in there?  If not, can you lock it into the lower, with the upper removed from the lower?  Those answers are gonna tell you where the issues are.  

[survivalshop]

I can tell you from experience , not every brand of Mag will fit in all brands of Receivers . I had a CMMG Billet 308AR Lower that would only work with Steel Mags or Lancer L7's , none of the New at the time ( first Gen) LR PMags would work , I would get FTF with them on a regular basis . When they came out with the Gen 3 PMags , they worked fine . Tolerance Stacking from different manufactures is what's going on .

As posted from 98 above , see how they fit & they will hopefully just need some tweaking to work . The main issues with the early DPMS Mags was Feed lip issues .

[98Z5V]

2 hours ago, survivalshop said:

The main issues with the early DPMS Mags was Feed lip issues .

Yep.   I have one 19-rounder that needed the feed lips tweaked.

[bubbas4570]

98, nope it will not lock in with bolt locked back. And I haven't tried fit with upper removed.

There is no contact between bolt and feed lips, as no scratches present from moving bolt across mag/nor can I detect bolt drag while eh and cycling bolt.

 

I think I just found ano the project.....and something I will mess with until I get it to work.....??? one of these 3 outcomes at the end for me.

[98Z5V]

17 hours ago, bubbas4570 said:

98, nope it will not lock in with bolt locked back. And I haven't tried fit with upper removed.

If it locks in with the upper removed, that means the mag feedlips are contacting the upper receiver cuts, and the upper receiver is keeping it from locking in.  If it doesn't lock with the upper removed, that will mean you need to check the cutout on the left side of the mag - something there is stopping it from locking.  Or the pad on the mag catch is Yuge...  Things to look for...

Just pivot the upper forward on the pivot pin, and try to lock the mag.  If it goes, then try to close the lower and pin it with the takedown pin...  SOMETHING is gonna happen...  

Edited December 4, 2018 by 98Z5V

[bubbas4570]

7 hours ago, 98Z5V said:

If it locks in with the upper removed, that means the mag feedlips are contacting the upper receiver cuts, and the upper receiver is keeping it from locking in.  If it doesn't lock with the upper removed, that will mean you need to check the cutout on the left side of the mag - something there is stopping it from locking.  Or the pad on the mag catch is Yuge...  Things to look for...

Just pivot the upper forward on the pivot pin, and try to lock the mag.  If it goes, then try to close the lower and pin it with the takedown pin...  SOMETHING is gonna happen...  

98, no it doesn't lock even with the upper pivoted forward. I guess I'm going to have to pay a little more attention to exactly what's going on. This just turned into a real project.

It tries real hard to lock in like a grownup magazine, but still isn't quite there..... ??

[Lane]

I went through this with a magazine that looks very similar to that one. Mine is marked as made by ACS, and not DPMS; but the construction appears the same.

This magazine wouldn't latch no matter what I did; so I removed the magazine catch from the lower. Holding the magazine in tight and looking through the hole in the mag-well, it was clear that the catch hole in the magazine needed to be opened up on the top side. Yours could be left, right, or top of course; maybe even all of the above. I did all this with the upper installed and the bolt closed. Once I figured out what was going on; I slid out the floor plate and ground the catch hole in the magazine taller with a small flat file. Then I tested, cleaned the shavings, and put it back together. 

Even after that; the feed lips took some wear from the bolt carrier, so I cycled it with oil repeatedly. It is likely you could modify the feed lips to the same end, but I personally assumed it better to do that as a last resort. I don't think it took my more than ten minutes all told, but I did have the punch (to remove floor plate which was very tight) and flat file close at hand. I only removed the guts of the magazine to make sure it was clean inside when I was done.