My friend Alex Bosco of SB Tactical sent me his new collapsing arm brace for the SIG MPX pistol. Tim Harmsen got one earlier and posted a video about it which Nathan S. posted about. You can see that post here.

Having used other SB Tactical braces this one is just as good and in fact I find it better than the other braces previously available.  It is minimalistic. There is so little rubber material compared to the original SIg Brace and the other brace designs Alex has.

The new collapsing brace uses the same slider bars as the MPX collapsing stock.

You can see the button to release the bars from their detents.
The small detent below the two holes is for the locking lug to lock the brace to the rear of the MPX receiver.

One thing that I did not like was the sling loop that is on the brace. The same loop can be seen on the MPX collapsing stock. It can interfere with the brace collapsing all the way and it is redundant since the MPX has a QD hole directly behind this sling loop. It was a simple matter of unscrewing the hex set screw. Be careful though, there is a spring that holds the button/locking detent against the slider bars and it is under pressure. Mine flew out when I slid that trapezoidal block out of the way.

Once I found the spring, I just simply pulled the sling loop out and reinstalled everything. As you can see below, the underside of the brace is much cleaner and you can see the QD socket in between the grip and brace. No need for a sling loop if you have a QD sling loop.

One noticeable improvement of this brace is the use of elastic for the forearm strap. It is so much more comfortable than the previous straps used on the SB Tactical braces.

Thanks to my friend Corey I was able to compare the collapsing brace side by side with the regular folding MPX brace.

Fully collapsed, the MPX brace sticks out a bit more it measures 21 inches closed and 25.5 extended OAL.

Fully deployed the collapsing brace is not as long as the traditional MPX brace resulting in a shorter length of pull.

An obvious benefit is how slender the MPX is when the brace is collapsed. You do not have the bulk of the side folder.

But how does it cheek? Some people may have issues with this brace as a cheek rest. I am used to my Troy M7A1 PDW stock on my AR so this feels normal to me. Also I like to run my guns short and keep my nose to the charging handle. I have had a few people complain about how short the Troy M7A1 stock is and this is similar.

There is very little play in the slider bars and they lock up solidly. The slider bars have three positions. Closed, middle, and fully deployed. If you press the release button and hold it down you can pull the brace out all the way in one motion. Now it is not a fault of SB Tactical’s but the slider release button position is in a bad location. It is on top of the brace setup. The MPX collapsing stock uses the same setup. I would have preferred the button to be accessible by the firing hand still on the grip, just like the M7A1 is. However that is solely convenience rather than a detriment. I did get a chance to manipulate my friend Corey’s MPX pistol and the folding brace does take a bit of familiarity to close it. Opening and deploying the brace is a simple fluid action. Closing it is not. This new collapsing brace design is easier to close as you just push the detent button down and slide the brace forward.

This new brace is slated to be available in a month, according to SB Tactical.