Can the factory OEM muzzle device be removed?  And if so, how long of a muzzle device would have to be added to make this 26"+ long?  Or would a traditional buffer tube and stock get me the length I need?

I've handled / fired this at the range, but couldn't tell, and couldn't really get that great of a look at it.  Trying not to be "that guy" who is staring at the muzzle end of a rifle while in the range area.  

Very interested in SBR'ing one of these, but for my state I believe I need the 26" length.

I removed the muzzle device from mine and don't remember anything special about it.  I believe you can use an ar15 armorers wrench to get the device off.

No idea on the 26 inch OAL other than it won't be easy if you're looking to appease the ever changing opinion of the ATF

Let me guess...are you in MD? (If you don't mind my asking?) I'm about to move there myself (sadly).

If you are in MD, then I really don't see how you're going to satisfy the OAL requirements for SBRs in MD with the DDM4 PDW, unless you put on a very long muzzle device that will negate the entire purpose of buying a .300 Blackout AR pistol in the first place. The shortest SBRs I've seen on MDShooters.com since I joined are 10.5" guns with PW'ed flash hiders (e.g., DD MK18s with PW'ed Surefire 3Ps). The pistol version of the DDM4 PDW is still widely available in MD right now, though once the ATF's new brace rule goes into effect, it will become less useful, too.

No, Illinois.  
I get the real value of having a 300blk gun (to be able to suppress it), which is still not legal here, but I'd still like to build one anyway.  With my 2 current SBR's, I am almost positive the calculation was from the end of a muzzle device (if pinned) to the opposite end of an extended stock.  So if I could eventually pin a Surefire Warcomp, and add a conventional buffer tube and something along the lines of a CTR stock, would I be at or over 26".  That's really the question I'm trying to answer.

A 7 inch barrel should get you over the hump to get to 26 inches. I'm also stuck in Illannoy hell and waiting on a few stamps.

Thanks for this.  Sorry to hear you're stuck here too!

I was stuck in Chicago until I escaped to McHenry county last year. It's not quite the land of freedom but it's a lot better than Crook County.

Congrats on your escape!  I'm in Frankfort (Will Co).  Not as bad as Chicago either, but still in IL.

Just got one of these pistols, and that comp is TIGHT!!!
Wonder if DD used Rockset or something similar? Used a suppressor spanner wrench, it wouldn’t budge?!!

Get a Barska wrench and the brake will come off fine.