DDM4V7P FTF

[ReCh5048]

Hey guys,

I just purchased a DDM4V7P in 300 blk. My first 120 rounds had about 10 FTF with both sub and sonics while shooting suppressed. The casings eject fine but the next bullet gets wedged nose up by the BCG.

The gun was properly lubed 😉 and I was using 300 blk Pmags.

My guess is I’m over gassed but wanted to see if anyone could point me in the right direction. I currently have a law tactical folder, sb3a brace and H1 buffer. SBR tax stamp on the way (maybe i should have waited). I’ve researched the A5 system, JP SCS, and H2/3 buffers but the information is overwhelming. Any ideas so I get it right the first time?57078570795708057081

[mark5pt56]

Try one round at a time to check gas and full function(travel) of BCG, you should get lock back-insure it's the mag follower pushing the bolt catch up engaging the bolt itself. You are either getting either to much or not enough gas. Not enough if not locking, if you are then you have to much and will need bandaids. Something to look at also is if not locking, put a standard buffer in as the LAW connecter adds weight. For reference with a BCM .300 pistol I had no issues with a LAW and an H2 but I have no knowledge of the DD's. I used either Lancers or 20 round MP's. If that mag is full, it may not be pushing the next round up fast enough and if over gassed, will do this also.

[ReCh5048]

Thanks Mark!

It’s my first AR so everything is new to me. With the amount of gas hitting my face it’s hard for me to believe I’m under gassed. Also, the BCG has always locked back on the last round. I really don’t want to invest hundreds of more dollars on bandaids that might work. I’m really hoping to get the bandaid right the first time.

[1168]

Does it function properly unsuppressed?

[ReCh5048]

[QUOTE=1168;2731524]Does it function properly unsuppressed?[/QUOTE

I’ve shot 20 rounds unsuppressed and it ran fine.

[ReCh5048]

I called DD today and they’re bringing the rifle back in for inspection. Although, the issue has been a PITA the Daniel Defense customer service has been top notch. I’ll let you guys know what they find.

[everready73]

They have good service and should get you fixed up.

You could always talk to Clint at Black River Tactical if you determine it is over gassed. They offer gas block inserts to reduce the port size and it is a fix not a band-aid like a heavier buffer

[ReCh5048]

They have good service and should get you fixed up.

You could always talk to Clint at Black River Tactical if you determine it is over gassed. They offer gas block inserts to reduce the port size and it is a fix not a band-aid like a heavier buffer

Thanks. That seems like a good route if I can’t get it fixed. I’ll let y’all know.

[Iraqgunz]

No, in actuality he took the right course of action and DD should make it right.


They have good service and should get you fixed up.

You could always talk to Clint at Black River Tactical if you determine it is over gassed. They offer gas block inserts to reduce the port size and it is a fix not a band-aid like a heavier buffer

[Iraqgunz]

So just to be clear here. You are getting malfunctions with subs and supersonic ammo? What brand of .300 Blackout ammo are you using?

You should actually be conducting a lock back test as first mentioned by Mark5pt56.

Internet/Long Range diagnosis is hard. I would allow DD to thoroughly check the weapon and make sure they know what ammo is being used, etc...

[Caduceus]

Also, same magazine, or multiple?

Mods, plan on locking this until it's resolved by DD?

[ReCh5048]

So just to be clear here. You are getting malfunctions with subs and supersonic ammo? What brand of .300 Blackout ammo are you using?

You should actually be conducting a lock back test as first mentioned by Mark5pt56.

Internet/Long Range diagnosis is hard. I would allow DD to thoroughly check the weapon and make sure they know what ammo is being used, etc...

I was getting malfunctions while using both Hornady Black Amax 110g and Winchester 200g. Rifle was sent off this morning. Hopefully I hear something back next week.

[ReCh5048]

When I first contacted DD with the problem they suspected a magazine issue. They shipped me a magazine specific for a 300BLK. When the problem occurred with that mag they had me ship it back to be inspected.

[ReCh5048]

Gun as been fixed and is in the mail. Here’s the DD response.

“Inspected. Replaced the SB3 brace/tube with a DD pistol tube. Replaced the BCG (gas key leaks) and polished the feed ramps and chamber. Using the supplied mags, test fired 80 rounds on 125gr. and 220gr. Remington. Half suppressed. Had zero issues.”

Seems like it had a leaky BCG. Now my question is, would the SB3 brace/tube cause a FTF over a DD pistol tube? Or was that more for the legality reason for an SB3/Law tactical combo?

Excited to get my rifle back!

[thegreyman]

Interesting. I have a DD M4 V7 - no problems whatsoever.; I replaced my SB3 brace pistol tube with a DD Factory tube because SB3 Tubes had smaller diameter than DD tubes, and
I like DD parts.

[everready73]

No, in actuality he took the right course of action and DD should make it right.

I acknowledged him sending it back. That's what I would do first too.

It could still be over gassed even if fixed and an insert would be a good idea if so imo

[MistWolf]

This type of malfunction is not directly caused by over gassing. It's caused by weak extractor and/or ejector springs. The dents on the case mouths are from catching on something because they are not being properly rotated out during ejection. The empty impedes the BCG as it's is trying to feed the next round in the chamber. This causes the bolt to override the base of the new round. Over gassing places extra stresses on the springs, exposing those springs which are only marginally functioning. But if the springs are good, the AR would need to be extremely over gassed to start malfunctioning like this.