DD MK 18 AR Pistol vs Sig Sauer P556xi

AR/M4 AR General Discussion
1

If you had to choose between the Daniel Defense MK 18 AR Pistol or a Sig Sauer P556xi which one would you choose.

Both are quality manufacturers but the biggest differences of the back for me to consider is:

  • buffer system vs piston system
  • rear charging vs side charging
  • short vs long stroke

So which one and why?

2

Why a pistol?
What are you gonna use it for?
What state do you live in?

3

I have not heard good things about the 556xi. This after all the problems with the introduction of the previous 556R… I wouldn’t touch one. SIG may be a quality manufacturer when it comes to pistols… not so much with their commercial rifles. They are a far cry from a universally well-regarded manufacturer like DD.

4

I’m out in good ol’ California …

I too am concerned about the reliability of the 556xi but figured it would be cool item to add to the safe. I have other ARs so I was also thinking about other platforms

5

If you’re thinking about other platforms you might consider a CZ Bren805 pistol. The DD Mk18 has overgassing issues, and the 556xi is a poor attempt by Sig to make a modular rifle system. I have a feeling with the MCX making a debut on the market the 556xi will fall by the wayside.

6

I have a MK18. The DD is over gassed but I wouldn’t go as far to call it an issue, the gun runs. It won’t cause the gun to stop operating. I have a H2, and a blue springco to slow the cycling. I’ve never had a singe stoppage with that gun.

7

The gassing of the DD MK18 is a non issue on both my uppers.

8

The people have spoken. I didn’t expect a shut out in the polls, but that’s an indicator not many have faith in sig

9

DD makes a great gun and the mk18 is a great sbr platform with proven pedegree.

Hard to not like it.