DD MK 18 AR Pistol vs Sig Sauer P556xi

**xstrensic** · 09-03-15, 18:43

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?

**JulyAZ** · 09-03-15, 20:35

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

**henschman** · 09-03-15, 21:34

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.

**xstrensic** · 09-05-15, 12:42

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

**Leonidas24** · 09-05-15, 13:20

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.

**JulyAZ** · 09-05-15, 14:46

Originally Posted by Leonidas24

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.

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.