Sig M400 pistol buffer ?

[svh]

I have a Sig M400 pistol. Have an AAC 9" 300 BLK upper on the way. I also have a can in jail till June or July. AAC says use H2 buffer with receiver extension. There is no markings on stock Sig buffer. Anyone know which buffer they ship with ?

Also any advice on other buffer systems I might need ? I will be shooting supers and subs, suppressed in the future.

NOOB QUESTION : Receiver extension ? Do I have one ? Do I need one ? Is that just the length of the buffer tube ? Any info on this will be greatly appreciated.

Thanks for your patience and help.

[Bullz]

Receiver extension = buffer tube. Take out the sig buffer and get the H2 buffer. Anything marked H2 will work fine.

One example: http://www.bravocompanyusa.com/H2-Ca...rbine%20h2.htm

The standard M400 comes with a buffer of near equal weight to a carbine buffer. No idea about the pistol but don't mess with it. Just put the H2 in and you're good to go.

[svh]

Thanks again, and sorry for the green question. I should have read more, and asked less.

[Bullz]

One other thing... once you get that H2 Buffer in there, put the sig upper back on and check for function. Sig was (and may still be) using a funny bolt carrier that's not a full auto and isn't quite a "standard" semi auto... it's some kind of hybrid. Check to see what you have. I don't have a lot of info on it, but I would suggest you throughly check things out with your standard 5.56 pistol upper if you plan on swapping uppers and not buffers.

Someone else may be able to offer more info on the nuances of Sig...