I have a DD m4a1 block II upper from brownells. I read that these have a 0.062 gas port size which is the same as Colt’s socom barrels. My colt socom barrels have always functioned fine with every ammo ive used in them

I took my DD socom carbine out today and with wolf 223, it is a single shot gun. The bolt wont go far enough back to strip another round from the mag. The casings eject at 3-4 o’clock, but not quite as far as brass cases do. My colts eat steel ammo fine

I also had multiples of the same issue with some old remington fmj ammo that I got from my grandpa

No issues with federal m193, m855 (pmc and imi), hornady 75gr hp, federal 69gr hp, old reminton 50gr hp, and 1993 manufactured Norinco 223 55gr fmj. All of these ejected almost identicle to one another at about 4-4:30

the pmc x-tac M855 groups extremely well if you take your time and do your part.

I knew going into it that my DD 10.3 wasnt going to feed steel ammo atleast not un-suppressed, but the carbine that should be gassed the same as my colts not working with steel or the old remington fmj for some reason, is concerning.

Does this sound like an under sized gas port issue, or is this the norm for a daniel defense upper?

DD upper, toolcraft c158 bcg, gas buster charging handle, h2 buffer, standard carbine spring

I love my DD cqbr block II, but I am questioning if something is wrong with the 14.5”. I had this upper pinned by RAW (excellent work) before having ever fired it as well. i suppose if the port needs to be opened, the gas block can just be slid forward and the port enlarged.

Also, shooting steel isnt the norm. i shoot steel just to make sure my firearms function with it but otherwise i shoot brass 556/223. I have an rc2 in jail so some day, these block IIs will be supressed as well

Obviously something isn't right.  Feel free to contact our warranty team at 866-554-4867.  More than happy to bring it in for inspection/repair.

thanks for the reply

Is it going to be an issue that it has a surefire 4 prong flash hider pinned and welded to the barrel? I assume that if the gas port is undersized, it could be enlarged by sliding the gas block forward some and drilling the port larger

We need to get it to the factory to see what we're working with.  Could be the barrel.  Could be the BCG.  We won't be able to tell until we can dive into it.

So the 14.5 should have no issues running any 223 or 5.56 ammo and needs to be sent in to be checked out.

My DD Mk18 upper will not function on steel cased 223 either. It has the same ejection patterns as the carbine does with brass at 4-4:30 and ejecting steel at 3-4 but not powerfull enough to cycle the next round. does the mk18 upper need to be sent in as well?

I read awhile back that DD used to use a 0.082 port of the 10.3 barrels and they would feed steel but were far over gassed so they switched to the 0.070 port which requires quality brass ammo, but runs fine on brass both suppressed and unsupressed

We recommend high quality, factory loaded brass cased ammunition in all of our platforms.  We do not recommend refurbished ammunition or handloads.  We also do not recommend the use of steel cased ammunition.  While it might function, it wears out extractors much faster and can lead to chambering/extraction issues dependent on external coatings that may be applied to prevent rust.  Also with steel casings, the casings don't expand against the chamber walls like brass cases do.  This allows expanding gasses to leak back into the action and not down the barrel where they're supposed to.  This is a cause of short stroking.  

Hope this helps.

In your personal opinion, would you send a rifle in for short stroking on tula (wolf wpa/tcw) ammo? It fed all factory brass ammo fine and ejected all of it regardless of bullet weight into the same 4-4:30 area with an h2 buffer. The only brass ammo that had issues was a plastic ammo carton of what was labeled “remington” and was fmj.

federal m193, pmc and imi m855, remington 50gr hp, hornady 75gr, federal 69gr, 1993 dated norinco 223 all functioned fine

When I get a suppressor, it will further add to the back pressure in the system anyway and being over gassed wouldnt be good either.

Personally, I wouldn't send it in.  If it's working with everything other than Tula, I just wouldn't shoot Tula any more.  Sounds like the rifle is shooting as it should with the types of ammo we recommend.

thanks for the replies! the barrel seems to really like m855 so that’s good

Tula and some of the other ammo like that often doesn’t run an AR.

It’s not just that it’s light loaded, the power used creates a pressure curve that drops off too fast and there’s just not enough gas to function.

Personally, I don't shoot Wolf in any of my 14.5" ARs with carbine-length gas systems (i.e., all but one of the guns I own).

I have a DD M4A1 with a SOCOM barrel from the Brownell's upper, and it has functioned flawlessly with everything else I've run through it. I mostly run M855 from a GOV contract overrun that is in pretty good condition (bought thousands of rounds from AIMSurplus in 2020 and I have yet to exhaust the supply).

Don’t shoot steel cased ammo.

99% of people who buy the block II 14.5 and the Mk18 want a gun that’s perfectly gassed.  In order to run .223 steel you need most of what the commercial market offers; gas ports opened far too much.

Curious if you ever ended up sending it in? I have a Mk18 pistol-turned-SBR that had no issues with Tula or Wolf from day one. It's also not over-gassed with M193 or IMI 77gr OTM.

But something that may be helpful or relatable: when I built up my 12.5" using a Criterion Core, Badger Ordnance TDX gas block, carbine RE, Sprinco Blue, and H-3 buffer, I really didn't think that it would cycle Tula. And it didn't. I had to swap to a standard carbine spring and carbine buffer.

But after about 150 rounds or so it started cycling Tula just fine with the Sprinco Blue and H-3 buffer. So maybe you just need a little break in period for it to run steel?