Using an SBR MasterPiece Arms 930SST in a carbine rifle class

| August 10, 2015 | 2 Comments

I attended the QSI Training basic rifle class last Saturday with The She Shepherd.

My goal was to test the MasterPiece Arms (MPA) 930SST “Mini” MAC10. I had test fired it a few times but hadn’t trained with it yet.

The QSI basic rifle course is designed for civilians acting alone in a domestic environment. This means that participants still need to respect the legal requirements for self-defense, and here in Minnesota one of those requirements is to be in fear of death or great bodily harm. Another is that we must retreat if practical.

As such, we must be able to articulate why we felt the need to use deadly force. It is difficult to prove this at ranges past, say, 100 yards. Retreat is probably a viable option at those distances, and it may be hard to discern someone’s intentions at that range.

Targets at the QSI rifle class are between 40 and 70 yards. If the MPA930SST could perform well at these ranges, it would be good for the urban environment in which we would carry it.

I intend to do longer analysis of my final drills, but here’s a quick overview:

The Good

I was very pleased with the accuracy of the MPA 930SST. Groups with handloaded 9mm FMJ were less than 1.5″ apart at 40 yards.

QSI has students perform the “100 round drill,” wherein we shoot through 3 full magazines worth of ammunition. Move, fire two rounds, move, repeat until all mags are dry. This stress tests the firearm and the student. At the end of my 100 round drill the vast majority of my rounds were on the body midline, a 2″ wide strip that represents the spine. Shots outside of the CNS were in the heart and lung area. Still not bad. I had some rounds outside of the “center mass” area, and those were completely my fault.

As I’ve stated before in my Glock NFA enclosure reviews, a big reason to have a stocked pistol-sized firearm is that added stability and recoil management from the stock. The MPA 930SST is no exception. Yes, I can shoot as quickly with a pistol, but not as accurately. Or I can shoot as accurately with a pistol, but not as quickly. A stocked “mini” SBR allows me to do both.

The (now discontinued) Primary Arms reflex sight did a great job, and is on its second year of battery life. I was impressed with how easy it was to see the green dot during bright sunlight, shooting in an environment dominated by green grass. I expected the optic to be hard to see, but it wasn’t.

I was also happy with how I am using cover and concealment. I am also doing a better job of acquiring my sights before leaving cover. The shorter length of the 930 made it easy to navigate around obstacles during drills.

I purchased the improved hammer from MasterPiece Arms. It was comfortable to use the entire day and did not have the “trigger slap” associated with the original hammer.

The Bad

This is true for all firearms, but I really felt like the 930SST demanded my full attention at all times. Some firearms, like my PPS-43C, are so forgiving that it’s almost a challenge to miss. If I rushed my shot, the 930 let me know. I  missed far more than I wanted.

I could tell when I got into my own head. “Don’t miss” was usually the last thing in my mind before I pressed the trigger — and then I missed.

More training is needed!

As an aside, the BLACKHAWK! waxed canvas satchel was a little too small to serve as a “war bag” once the shooting started. I had difficulties stowing my spent magazines, and accessing fresh ones. I wish the bag was just slightly larger, or only had one divider. I’ll write a separate post about my experience later.

The Ugly

I had some reliability problems later in the day. Before class I corresponded with the folks at MasterPiece Arms, and they gave me a known working factory polymer mag, as well as tips on proper feed lip dimensions for STEN mags. This information helped a lot.

I adjusted three STEN mags (plus my shorter, “contact” mag I didn’t use in class). I did not have a single problem until the final three drills of the day. Then everything seemed to fall apart, and I had a lot of malfunctions, including several extended stoppages that could not be solved with a “tap, rack, ready” approach.

By the time the malfunctions happened I’d fired about 300 rounds. I am not sure if this had something to do with it or not. It was very odd that I fired the first 300 rounds without a single malfunction, and then had several malfunctions during the last 100 rounds of the day.

I was able to clear all of these malfunctions, but it reinforced my belief that if one were to consider buying either the 930 or the larger 30 series MAC firearms they should go with the DMG series that accepts Glock magazines.


Despite the 3.5″ barrel, the MasterPiece Arms 930SST is more than capable of hitting human-sized targets at 70 yards. It probably has better reach than that, however the focus of the class and the range we trained on constrained us to that distance.

As with all shoulder-fired firearms, the addition of the stock helped with recoil management, consistency, and stability.

I wish I could trust the polymer factory magazines more (I’m 50/50 on them so far). The surplus STEN mags are also finicky, but can be easily “adjusted” and cost about $4 before shipping if you buy them in bulk.

If you already own an MPA 30 or 930, I recommend you get in as much live fire training as possible. I had to concentrate a lot more when firing the 930 at longer ranges. You may not have this issue, but I always recommend more fight focused training.

Despite my problems, it was a big confidence booster to complete a rifle class with a 3.5″ barreled vSBR. I know that I can make fast, consistent hits if I practice, and I will improve. I will continue to adjust the STEN mags until they are reliable, and add the MPA 930SST into full-time rotation as an EDC bag carried firearm.

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.

2 Comments on "Using an SBR MasterPiece Arms 930SST in a carbine rifle class"

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  1. Mustascheo says:

    What did you use for the stock on that? Ace or something similar?

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