If I were designing it, I'd size it to fit the bigger end (1.25") of the common spectrum.  You can wrap some tape around the tube before putting the brace on to size down, easier than you can reduce the tube O.D. or brace I.D. to size up.

I hadn't planned on adding a brace, but something about the quick removal of the Strongarm system appealed to me this week, and the fact that it's one of the few that fits my narrower Brownells tube...I went ahead and ordered one yesterday.  I'll report back with how good the fit is.  The mounted brace won't fit in my discreet carry bag, but a mere two allens to mount it at the range makes it a non-deterrent.

My Strongarm arrived today.  As promised, here are my initial impressions.



Fit and finish is great, and the side profile blends in perfectly.  The measurements are as I hoped, fitting nicely behind my preferred cheek weld position.

The height of the brace is a bit puzzling, though.  Its contour is presumably meant to cradle the forearm, but it only extends about halfway down the grip's length.  The only way I can get my forearm to fit the brace's curve is with the gun held at hip height, far enough back that my elbow is behind me and the grip is right on my hip.  At that point, you could almost pinch the bare buffer tube just as well...  Held any higher and/or further away from me, I have to angle my wrist down so much I can barely wrap my hand around the grip.  This is my first experience with an AR pistol brace, so maybe that's normal?  I hadn't given it any thought from pictures.



The Brownells pistol buffer tube is roughly in the middle of the Strongarm's O.D. range.  You can see how it clamps on the side of the tubes but has air space at the top and bottom.  I'd like to see Doublestar add some oblong rubber shims in the future to even out the stress.  Probably not a big deal, but better is better.

The velcro strap should be 0.5" longer, IMO.  It's a bit awkward to tuck into place and wrap around the other side, like it arrived.  It's also very crinkly that way, with the hook and loop sides moving about fairly freely.  If it were a little longer, you could fully wrap it under the bottom, around the left side, over the top, and stick to the fuzzy side with no tucking.  It can just reach presently but doesn't get a solid hold unless really stretched tight. I might cut the hook side off and sew a longer piece on, and maybe reverse the hook and loop orientation so the soft loop side is stretched over the brace.  Currently, the scratchy hook side contributes to the noisiness.

I don't plan to use the QD mounts (got one on my endplate), but they're good to have just in case, and the included QD swivel is a nice touch.  I'm a little surprised it didn't come with an allen wrench, but I have plenty of them.

Installation and removal is easy, but I was pleasantly surprised to see that I can still just barely squeeze the gun in my carrying case with the brace on, although it'll require reconfiguring the foam.

Your buffer tube really needs to be 1.190" or less.   I tried a couple of "mil-spec" and they were too large.  Screw that, so I brought the tubes onto work with the brace and chucked one into the lathe.  1.195" was a no go.  1.192" still no go.  I had to hit 1.190" for it to fit. Few have that luxury and I don't see a downside to opening up the bore on the brace.

Got home this morning from Iraq and am trying to stay awake till tonight.  I ordered the SA brace and the other pistol buffer tube that DS offers.  The pistol tube kit with the end plate and foam is on the smaller side of what the brace will do.

Larue lower I got from the UU assembly Video I did.

Larue 2.0 upper with 12" barrel from the BuildAR group that I picked up off the EE.

Gotta find a crush washer for the flash hider I have for it.

Beautiful blaster.  It looks great with that tube and end plate vs. a regular pistol tube.

What's the recommended torque for the bolts