I finally bought a mid-length rifle. DDM4. All I’ve had/have is carbine length. I can’t tell a difference in anything so far except it won’t cycle Tula/Herters, some PMC.(short stroking) I knew this going in but was curious, what else won’t your AR cycle?
I know everyone’s setup is a bit different, but just curious, I don’t shoot
Tula much(more like pretty much never) but with ammo a bit tougher to find we are all compromising.
My mid length cycles everything I shoot in it. Make sure you apply a generous amount of lube to the rifle.
If breaking in the rifle and application of lube won’t rectify the issue, you may want to look at buffer/spring combinations.
It’s broken in and lubed. Shoots XM and my reloads fine. Just the lower power stuff won’t cycle. It came with an H buffer, swapped it with a ST-T2 Spikes buffer and no better. Just wondering if there is known ammo I should avoid with this rifle, or any other changes I should try. I know it may be unrealistic, but I would like the rifle to run pretty much anything.
Is it a 16" or 14.5" mid length?
How many rounds of full pressure ammo has been shot through it?
Every BCM mid length upper I own shoots whatever I run through it fine with a H buffer.
16" At least 800 rounds has been through it. Cleaned every 200 rounds so far.
Barring a loose gas key, gas block, the gas port on a mid length gas system is supposed to be .0625".
I wouldn’t be surprised if the Daniel Defense barrel had an undersized gas port.
Are they known for smaller gas ports? I don’t have anything here to measure that small to check.
Thanks for the info.
https://www.m4carbine.net/showthread.php?t=64673
I’ve personally seen this in 2 out of the 3 uppers I’ve used their barrels for.
Though they were all carbine length gas systems.
They shot the Russian stuff fine after several hundred rounds of M193 and M855.
I’ve never ran into this with BCM’s barrels.
It ought to shoot any quality ammo - mine does. My mid-length Noveske (H buffer originally, now with an A5) shoots PMC all day long and always has. It’s virtually the only range ammo I shoot. At least 8000 rounds of the stuff over the last few years. I don’t think it’s unrealistic to expect that a properly designed and properly set-up rifle will shoot “pretty much anything”.
I too would be suspicious of the gas port.
Dumb. I’ll call DD on Monday. I was just curious. Like I said I don’t shoot tula/pmc often but would like it to cycle when/if I do. It has cycled XM193 and PPU 100% from day 1.
Thank you for the info.
Sabre upper/BCM lower, loves everything. Eats a lot of Wolf because I’m cheap.
DD gas ports seem to run a little smaller than most others.
This is good for running the full pressure 5.56 it is intended to use.
The manual may even mention this.
No one should be surprised when Tula short strokes in a middy.
This is what I thought and was told by more than 1 person. I assumed it was an ammo issue by that, but now I’m wondering about the gas port issue.
No need to beat this into the ground anymore, I’ll call DD in the AM and see what they have to say. Thanks again for the responses.
How many rounds have you fired through it? When I bought my first BCM 16" middy upper, it would sometimes short-stroke with PMC Bronze (which is the weakest ammo I own) using a Springco white spring and LMT H buffer. After generous and frequent reapplication of lube and a breaking in period of only about 300 rounds, it just kinda worked itself out. Now it feeds and fires anything 100% trouble free.
I’ve heard of new midlengths needing a breakin period of 3-400 rounds using full powered ammo. I have not had a problem with my two midlengths even using tula during the break in phase. I shoot a lot of Tula as range ammo. Almost exclusively lately because I am hesitant to dip into my reserves of the good stuff until it becomes more readily available/reasonably priced.
I believe there was a thread regarding 14.5 midlengths being susceptible to malfs with weak ammo.
I’d rule out the other variables and put another couple hundred rounds thru the rifle.
Regarding gas port size on a midlength. Is the .0625 a standard set between manufacturers?
MFGs can do what they want with gas port sizes.
.0625" is what Colt uses for the 14.5" CAR gas M4 with H buffer.
That is the “known good” starting point.
Others go bigger and smaller.
There is no published equivalent for mid length gas.
That’s what I thought, potential discrepancies.
I would consider BCM’s 16" midlength a good standard.
The are smooth shooting and cycle most everything.
Their 14.5" midlengths can be finicky.
My barrel is a DD middy. It’s backed by a BCM bolt and VLTOR A5 system. Runs everything I’ve put in it.
That includes alot of Tula and wolf.
My DD 14.5 mid gas has a .071 gas port