Working on getting my pistol build together.  I have an Aero lower.  I just ordered a Stripped Blem Upper w/ build kit, PSA LPK w/ Umbrella Corp Grip and the PSA six position premium carbine buffer and tube.

I am up in the air about an SB15 brace or the Thordsen Custom Cheek riser or saddle.  That is what I went with the longer buffer tube,

I like the looks of the Phase 5 Tactical Pistol buffer and it has a carbine spring from what I can tell but is it too short to mount an SB15 effectively?

If I get the Phase 5 will I as a big man be able to shoulder mount it with some degree of comfort?

I'm 6'4 and went with the kak tube setup and I am very happy with it, if I were you I wouldn't use a carbine tube too many questions about constructive intent to risk that if you take it out in public

Eh I can see that but If I don't own a stock for it and have only ATF legal mounts on it I am not worried.  

I just want a tube long enough to mount a CAA saddle or cheek riser or the SB15

I am not 100% sold on the SB 15 yet.  But the Phase 5 seems too short.  

If I don't use the carbine tube I'll just use it for another build.

Will the KAK tube work with the Thordsen stuff?

ETA Thordsen has a letter from BATFE saying it is legal to mount their stuff on a carbine tube.

I have no experience with anything other than a bare tube and the sb15, I wouldn't recommend anything other than a sb15 having shot mine and having the success I've had there are people who don't like it but for what I wanted it to do it exceeds expectations and is easy to make almost permanent with some double sided tape and lighter fluid

Eta mine is on page 104 of pic thread if you want to see how kak setup works for big guys with the spacers

I like the look of yours.  

Just trying to decide on the sb15 vs the CAA and whether the pistol tube would be too short to mount.

I have the CAA on a Spikes pistol tube with foam cover and have no issues with shouldering.  I think the KAK tube would be nice being it is a little bit longer.  I am 6'2".

A carbine buffer tube is pretty much same length as most of the normal "pistol" tubes. The SB15 will not fit over adjustable carbine tube anyway.

If you want longer to facilitate the SB15, the KAK models are obvious choice, and they even have spacers now to offset the brace even farther back if you like. A rifle buffer tube is the longest tube you can get.

- OS

This is the kind of info Im looking for.  The Thordsen kit is what I am leaning towards right now and it will work on an adjustable.  Either way I have another lower...so it can be used.

My Sig PM400 11.5" came with the SB15 brace...the buffer tube only extends ~7.5" from the receiver, however you can adjust the SB15 up and down the tube and it will *not* budge (forward/backward/side-to-side)....I moved it back ~3 inches and it still wouldn't budge.  i.e. as long as the buffer tube you get has a large enough diameter, you don't have to worry too much about length.  Agree with the post above about the SB15 doing what it's supposed to do...I took my PM400 to the range a few weeks back, and it works great (I'm 6'1).  My bro has the 16" Sig M400...I shot both back to back and there isn't a noticeable difference in recoil (wasn't shooting rapid fire).  Pic of my setup is on p.105 of the pistol pics thread.

I run both. Here is what I have found.

I love the phase5 kit. I run a cheek weld. And have zero issues. I just hold it in the air and let her rip.
Very comfortable on a 7.5


I also run the KAK supertube with a SB16 and say it performs just as well.
Its not a stock..... meaning the SB15 is lacking the ergonomics that a magpul my offer...  but it works well for what it's purpose it.
The added length of the KAK tube is a def +1.

I like having both.
Not changing either.
Both are castle nut systems too.

As OhShoot said, the SB15 will not fit the 6 position tube.  The SB15 needs a round tube with no adjustment rail.  Don't modify the brace to fit.  There are several tubes out there that the SB15 will fit on.  The SB15 had a snug fit, not tight, on the tube I used.  It was made to fit the SB15.  I used a very small amount of super glue to hold the brace in position.  I'll use nail polish remover (acetone) to remove the brace if I have to.  This way it is very solid.

Well sounds like I have two options....get the Thordsen kit and use the tube I have on the way.

Or get an SB15 and a KAK or other similar tube.  

But the six position I have wont go to waste...I have two lowers.

Negatory. Perfectly fine to use a carbine extension as long as your stocks have a rifle or sbr they can go to.

Yeah I wasn't worried about this at all.