I know there are a few different manufacturers out there producing buffer tubes with a shoulder for the SB15.  I have had mine jammed on a cheap pistol tube from Amazon and I'm afraid it's a bit stretched out now.  I'd like a tube with a shoulder on it so it doesn't slide forward during firing (which it currently does).  Can any of you tell me which SB15-designed tube has the largest OD?

Here's a photo of my current setup.  You can see how stretched it is on this tube and that the diamater of the current tube steps up to create a very tight fit.  It took baby powder and some heat to get it on the first time.  If I can't find anything I'm thinking of putting some skaterboard tape on the current tube to keep it from slipping any further (just on the underside so it doesn't interfere with the charging handle).
DSC09885A by Chrazy-Chris, on Flickr

The KAC tube is the best imo.  It has a shoulder and you can get spacers if needed

If you're happy with it now...I'd just leave it. Like you said, you may have reamed her out too much and it may just slop on a small OD tube (good god...is it just me or does this seem like the "My wife sat on a 2-liter bottle...will she ever enjoy the company of a man again?!?!" kind of discussion?)

X2^^^^

I put a phase 5 buffer tube on mine. It's not the hexagon but just a plain round tube. It has a super large diameter and I actually had to put gun oil on it to slide the brace all the way on.

Is it this one ?

Exactly

hahaha yeah something like that.  The only thing I'm not happy with is that it slides forward a little bit when shooting.  I think I'll try the skateboard take and if there are issues there look at other options.

I had my brace on the Phase 5 tube like above and decided I wanted a tube with a shoulder. I bought the one from MAS Defense LLC which gives me a 12" LOP (perfect for me). The brace was stretched out and was way too loose on the MAS.

I took 1" wide Gorilla tape and put 2 wraps around the tube in 3 equal sections, far enough from the ends so you can't see it.

It was a BEAR to put on, but it didn't try to roll the tape. I basically screwed it on with downward pressure. No kind of lube other than elbow grease. It's extremely tight now.

Haven't lost any sleep at night knowing there's tape on there either.

MAS Defense

That's exactly what I need to do.  Is there enough shoulder that it for sure won't slip over it?  Does the charging handle interfere with it at all due to the extra material?

I don't see how it could slip over the shoulder just looking at it. If you did wrap tape around the tube, just don't put the tape next to the shoulder. Mines about an inch back.

No interference with my charging handle.

I used Spike's pistol buffer tube on two of my builds - and I had to drench both the outter part of the tube and the inner part of the SIG Brace, and then POUND them onto the tube. Have shots tons of rounds down range with no movement of the SIG Brace.

I chose the Spike's tube because it is the only pistol tube I am aware of that is made from 7075, everyone else makes thiers from 6061 aluminum. 7075 is nearly twice as strong as 6061.

Hope this helps,

cheers

tire iron