DD 14.5" Midlength FTF

AR/M4 AR Technical Discussion
1

Today I was able to get my new DD 14.5" upper to the range and had a FTF on every 8th round with my PMAG 10round/20 bodies. Specifications below. I thought it was a magazine issue, but I had my buddy who was running a STAG 16" carbine use my magazine with the same ammo and he had no problems. Therefore, back to the gun. Is it my H buffer should I go to a regular buffer? Did I not clean the BCG enough before taking it out to the range for the first time? When I received the new Upper and DD M16 BCG from DD it was covered in packing/shipping oil which was very thick. I am shooting my normal range ammo which is Fiocchi .223 55gr. The gun is very accurate, zero’d at 25 yards and I was hitting steel at 200 yards with ease. Just want my gun to cycle with out any Failures. Any recommendations appreciated. With the Failure to Feed I was seeing the bolt getting stuck half way closed with the next round halfway out of the mag and half way starting to go into the chamber. Once cleared, the round would have a noticeable dent in the casing. Details below.

Upper from Smartgunner/Daniel Defense
14.5" DD 1:7 Lightweight Profile Mid Length Gas System
DD Low Profile Gas Block
VTAC Troy 11" TRX Extreme
BattleComp 1.5 Black Oxide
DD M16 Bolt Carrier Group
Troy Flip up front and rear battle sights
BCM Gunfighter CH MOD5

DD lower built by Grant:
LMT LPK
BCM 6position Reciever Ext
Colt Castle Nut
G&R Tactical SS Buffer Spring
H Buffer
SOPMOD buttstock
Hogue Grip
Magpul Trigger Guard
Magpul ASAP

2

I find it hilarious that in almost every thread I see where someone complains about their gun not working, they list the mag of choice as PMAGS. I just deleted a bunch of text because I don’t want to derail this topic and turn it into a PMag bashing thread. I’ll just suggest you try some different mags.

3

If it was the mag, why did my buddies Stag 16" who used my same mag not have the problem?

4

If it is the mag, it could be the gun/mag combination.

Not that I believe that it’s the mag, as I simply don’t know.

5

as an SME, if you have uncommon information about pmags, i think we’d all find it very interesting and relevant.

6

So as to not derail this thread, let’s look at what is going on. It doesn’t sound like an issue with the workings of the gun, since other than the 8th round, it supposedly cycles just fine. If the issues were occurring all the time, I’d be more inclined to think it was an issue with the gun itself. I’m a visual person, so it would be easier with a picture, but I’m wondering if there is an issue with the tension of spring getting weaker as the mag empties and not pushing the round up fast enough as the tension decreases. I’m guessing these are modified mags for a Kommie state? I’d suggest calling the company that modified them.

I have seen a DD gun that malf’d a good bit. I don’t recall what it was doing, but I recall the mag variable being eliminated. Also, the malfunctions were sporadic, not consistent like your every-8th-round issue. Being a new factory rifle, I think the owner was going to just send it back to DD.

I get what you’re saying about the mag working in your friend’s gun. When I had PMags, most of them would work great in one of my guns, and work like shit in other guns. The idea of having certain mags that will only work with certain guns of mine was not satisfactory, so I moved on to other mags. If you try some other mags, you can eliminate your PMags as the issue. To clarify, you said, “bodies” implying more than one, but you spoke of your friend shooting a singular mag. Is this your one an only mag? Did you shoot any of your friend’s mags? The magazine is the easiest variable to eliminate.

7

I would agree. Many SMEs and IEs swear by them, and literally protect their lives with them. What are your findings?

What do you recommend instead? Plain ol’ USGI? USGI with magpul follower? Lancers?

8

I say you clean the gun and BCG properly and remove all the factory gunk. Lube with the proper gun oil of choice and take it back to the range. I’ll bet it will be spot on without another FTF.

9

I would take it a step farther. It usually seems to be 20 round PMAGs.

Only Failures I have had on 2 guns have been because of a 20 round PMAG. I just tossed the mag and my 30s work great.

10

You’re correct these are CA modified mags. I have two of them. But only one was consistently giving me the problem on the 8th round. They are not new mags as I have had them for a while and have used them on my own Stag 16" with out any problem. I did give the one I was consistently having a problem with to my buddy to see if he would have the same issue. As earlier indicated he did not.

With that said, I’ll get some new mags and go back to the range. I did give the BCG a good cleaning as well.

11

I have a 14.5" midlength gun that was doing something similar. I swapped the H2 buffer with a standard buffer and it works fine now. One more variable to eliminate.

12

I think you just figured out the cause of your problem all by yourself.

Cameron

13

The other mag did give me the same problem just not nearly as consistent as the “bad one.”

14

I’ve had the same problem with both of my 20rnd PMags, typically when there are only 2 or 3 rounds remaining; which tells me weak magazine spring tension. No problems with the 30 rounders that I’ve been running for a couple years now.

15

At any point did you try your buddy’s mags in your gun? You said that your mags ran alright in his gun, but you didn’t mention whether you tried his mags in your gun.

16

Great question. I did not. He only had one mag and I didn’t even think to try it. For some reason while at the range I was caught up thinking it was the H buffer. I think new mags are definitely my first step.

17

Might it have something to do with the popularity of PMAGS?

18

My buddy has a problem with the CA modified 20 round PMAGS. Personally, I don’t have a problem with them, but he says his LWRC A2 doesn’t seem to like them.

I believe this has something to do with the spring in the CA compliant PMAGS being overly compressed with the 10 round block. The vendors of the CA compliant PMAGS have to make sure that LEO cannot fit 11 rounds into a 10 round magazine. This causes PMAG dust covers to not fit, making it very hard to insert a loaded mag into a rifle with the BCG foward, having to insert 9 rounds instead of 10, etc.

I believe these issues with 3rd party modified PMAGS are the reason that Magpul is looking into making official CA legal magazines.

19

We make A LOT of magazines (different colors, round capacity, and magazine types). While we test in as many different platforms, type of ammo, shooting schedule, etc. it is impossible to try everything. If anyone is having issues with our product please feel free to contact Tech Support and we will do everything possible to make it right.

Unfortunately it is not possible to verify a third party’s manufacturing process and therefore we cannot guarantee that our product will work after they (the third party) modify it.

On a personal note,
I take my job very seriously because I know what it is like to trust your life to your weapon. If anyone has any questions or concerns please feel free to contact me and I will do everything I can to help or run it up the chain to make sure it gets fixed.

  • And before anyone asks, I cannot discuss the particulars of when any new products are coming out so please don’t ask.
20

Thanks for the reply Jimmy. But its definitely a third party who adjusted the mag to meet the CA laws. With that said, any chance you will be making 10 round PMAG’s in the future for sale to the public?