MPA 930SST SBR Test Fire Review

I finally got a chance to test fire my MasterPiece Arms 930SST very short barrel rifle (vSBR) last weekend. It took a long time to assemble the 930SST due to issues attaching the vz 58 stock.

The 930SST makes a good vSBR, but unless you’re on a tight budget or are the Do It Yourself type you might want to buy the 930DMG instead.

Dimensions and Firing Impressions

The MPA 930SST is about the smallest 9mm SBR you could purchase.

Weight, unloaded 4 pounds, 3.4 ounces
Weight, loaded (15 round magazine) 5 pounds, 2.2 ounces
Length, folded 9 1/4″
Length, unfolded 17 7/8″

It amuses me that the unfolded length of the 930SST is just a bit longer than the folded length of my .300 Blackout AR15 pistol build.

If you are looking for an ultra compact shoulder-fired weapon this form factor might be your best choice. There are some exotics like the TP9 but the MAC10 design is well known and there are inexpensive parts everywhere.

Speaking of inexpensive, the total cost of this vSBR build — including the NFA stamp — was $806. The MPA 930DMG is $679 alone before shipping.

Shooting the 930SST made me laugh. Recoil is very minimal. I was pleased by the accuracy, and with a micro red dot you will not have a problem keeping rounds on target at expected contact distances.

Here’s my target after firing 4-round rapid bursts at 10 yards:


I look forward to shooting the MPA at 100 yards.

The upgraded “no-slap” trigger (top) is much nicer than I expected, and catching the link is easy. The anti-slap trigger is found in current production MPA 30 and 930 pistols. It’s available as an upgrade directly from


Unfortunately I did have some feeding issues with the 930SST. I fired about 200 rounds this weekend and about 300 rounds total through the 930SST so far. I’ve had a consistent feeding problem where a round goes “tip up” at about 45 degrees in the chamber. A tap-rack-ready will solve most of these problems, but sometimes I have to do an extended stoppage clearance. This requires the removal of the magazine and running the charging handle several times. Luckily the 930 is very easy to clear, even with these “type 2” malfunctions.

I’ve used the stock MPA / Tapco magazine and several STEN magazines, including one I cut down to hold 15 rounds. I’ve also fired several different types of ammunition, including Aguila, Wolf, Federal HST, and handloads. There is no discernible combination that is more or less reliable than the other. I think the feed ramp may have something to do with it, and I have a query out to Masterpiece Arms for help.

Conversion Process

Converting the 930SST to what you see here required machining work. I also had to make the unplanned purchase of the US  Machinegun stock bracket, but it did its job well. The bracket attaches underneath the 930SST via a provided bolt. My machinist friend drilled and tapped the bracket, and then ground off a piece of the bracket so the vz 58 stock would sit flush.


The thread pattern for the vz 58 stock is unusual, which required the use of yet another specialized tool. Without my friend this build would have required sending the 930 SST off to a gunsmith, adding time and expense to the build.

I chose the vz 58 stock because it has a very small profile and is made of one piece of steel. It is robust, but also thin. The AR15-style stocks often put on MPA SBRs or pistol builds almost doubles the thickness of the weapon when folded. The vz 58 stock aids in concealment, and makes drawing from the BLACKHAWK! Diversion waxed canvas satchel much easier.



Overall I am impressed with the MasterPiece Arms 930SST vSBR. I think that many of the concerns I have would be addressed with the DMG version: weight, attaching the stock, feeding issues, and magazine consistency. However, if you like to do your own builds or want to build a vSBR for as little as possible, the 930SST is a great candidate.

Build cost

Item Cost
MPA 930SST $360
MPA anti-slap trigger $48
vz 58 stock $58
US Machinegun stock adapter $65
Primary Arms reflex sight $75
NFA stamp $200
Total $806

About the Author:

Short Barrel Shepherd Short Barrel Shepherd is a regular guy and works to make Web sites and mobile apps easier for people to use. He spends his free time attending fight-focused firearm, knife, and combatives training, motorcycling, writing, and playing games. His daily carry is a Glock 19 pistol and an AR15 .300 Blackout pistol in a backpack.
Filed in: Reviews Tags: , ,

10 Comments on "MPA 930SST SBR Test Fire Review"

Trackback | Comments RSS Feed

  1. J Eisenhut says:

    Too small? I totally understand your quest for the best SBR rig. However, I have yet to see the best of both worlds between folded length and fully deployed length. I’m a big guy so maybe that sways my mind a bit because lots of these type firearms are too small for my comfort. I say continue your quest…I’ll continue to read your blog and watch your YouTube videos too.

    • Short Barrel Shepherd Short Barrel Shepherd says:

      Thanks for watching, reading, and commenting! I am slowly (mostly due to financial reasons) building up a multi-part series about how a person’s size makes a huge difference in the firearm and bag they can carry. The She Shepherd is 5′ 2″ , I am 6′ 0″ , and we have some juggernaut friends who make a full-sized pistol look like a pocket blaster.

      Your mind is in the right place — what may be on the small side for me may be micro for you, and what you consider just right may be gargantuan on The She Shepherd.

      Stay tuned 😀

    • CR Williams says:

      IF you’re willing to forgo the easy shoulder mount a stock provides then you might could run a smaller pistol with buffer tube (assuming adapters or attachments can be had for the chosen pistol) and just assuming a cheek weld. Not the full four-point contact but still more than two. I’m going this route for the present.

  2. B R KURTZ B R KURTZ says:

    I love my MasterPiece MAC (the full size version). I also like my VZ61 Skorpion (yes 32acp). Im NOT a small guy but clearly the smaller guns “carry” better. Yes they have some limitations; but I think that is made up by being able to carry them unnoticed where a bigger bag might raise attention. Anything larger requires a back pack at least; but these are purse size guns.

    I also have a side cock version. Yes its nice to be able to use optics, the problem is that the side cocking handle adds width. Im tempted to swop the upper for a top cocking version. It would mean abandoning the optics; but I think the role this is likely to see would benefit more from a smaller package than a red dot.

    Bolt forward / chamber empty / loaded mag makes sense over the slow to reach safety lever. Im not sure I see the virtue of a cut down mag, especially one with only 15 rounds. Have you tried 20 rnds? That would seem to be a good compromise.

    On my full size “MAC”, I added the web strap that attaches on the barrel. Remember to pull it back!


    • Short Barrel Shepherd Short Barrel Shepherd says:

      You do realize this ENTIRE build is your fault, right? 😀

      The cut-down mag is purely for concealment and faster deployment. The dimensions of a full-length STEN mag force the MAC into a larger bag, at which point one might go up to a larger sized weapon.

      With the cut-down magazine my 930SST fits quite easily inside of the BLACKHAWK! waxed canvas satchel or The She-Shepherd’s Vertx Commuter Sling bag.

      That being said, you could probably do just fine with a 20 round contact mag.

  3. vanderlin says:

    boy, if the 930 dmg can be shown to reliably feed HP ammo I will be all over it like a bumb on a baloneghy sammich and I’ll put a tri lug mount on it for suppressor.

    • CR Williams says:

      I’m having the same issue with a 30DMG (like the 930 but different barrel threading) that Shepherd is having with the SST and including FMJ, usually toward the end of the magazine. I have extra-power magazine springs on the way to see if that resolves the issue like it did with the Aero Survival Pistol.

  4. Martin Luther says:

    Have you or any of the other commentators considered sbr-ing a Glock with a Mako Group stock? The stock doesnt collapse but goes on and off fairly quickly. I like the idea of using a RDS Glock in 10mm or 357 sig with this stock.

    • Short Barrel Shepherd Short Barrel Shepherd says:

      Hi there! We did some testing of the ENDO stock, which is similar in design to the Mako Group one. Two out of the three testers found it difficult to reliably acquire the iron sights.

      If there’s enough interest I could evaluate a Mako Group stock, but after my issues with the KPOS I am reluctant to directly support that company again.

  5. Martin Luther says:

    What got my interest was the military arms channel review of the Mako stock Unlike the Endo its got a decent cheekweld.

Post a Comment