MPA 570SST...Budget Friendly PDW

MPA 570SST SBR

Couch Pic, lol

MPA 570SST SBR

Pros: Light weight, ease of operations/manual of arms, comparably inexpensive, accurate, extended range vs pistol calibers, cool factor

Cons: Clunky ergos in stock config, expensive plinking ammo, little use as a pistol, **can’t disassemble without tools

Nice Small Package

Here's a quick review of the MPA 570SST SBR. I purchase the pistol about 3 years ago on a whim. Most of my peers thought it was an ugly baby. But I saw the function over the form, a sub-$600 dollar 5.7x28mm on a extremely simple semi-auto MAC-10 action. I had seen a couple articles on the Masterpiece Arms pistol and immediately thought that would make a perfect Personal Defense Weapon (PDW). What better, they cost significantly less than an FN PS90, the only other rifle in this caliber. I had always been interested in the 5.7x28mm round and had fired a few FN 5.7 pistols in the past. They were always really accurate but the cost always turned me off, $1000+. When the FN PS90 arrived locally, I rented one by just didn’t like the ergos and it was $1400!

Lower Receiver

Disassembled

Anyway, I receive the pistol, took it home and started my cleaning and inspection process.  I couldn’t find the instruction in the case (hidden between the foam and the case) so I googled how to disassemble a MAC-10.  It was a fairly simple process and everything looked nice and serviceable. MAC’s aren’t known for their finish but the fitment was fine. When I went to reassemble, I noticed  was running into a problem with the front rail.  I couldn’t get the leverage to push down the hammer to join the upper and lower. I called MPA and they told me it should work fine, just give it a little muscle. I tried but it still didn’t work well. I emailed back and forth with MPA about 3 or 4 times trying to resolve the issue. They were very courteous and helpful each time, but I never was able to rejoin the upper and lower thru the basic MAC-10 instruction, but they talked me thru removing the rail, and the lock-up was easily accomplished and rock solid.

First Shots Fired

I went to the range with it and ran about 250 rounds of FN SS197 thru the pistol. It grouped at about 2 to 3“at 25 yards from the bench. I started experiencing failures to feed, failures to fire, and failure to eject every magazine. At this point I was starting to feel like I got screwed with this purchase. I contacted MPA again and told them my issues and included pics of the firearm and the some spent cases, and light primer strikes. Again they were very helpful and tried talked me into some troubleshooting, but I was pretty upset and wanted a working gun or my money back. They told me to ship it back to them for service which I did, but had to do it on my own dime. I sent the pistol, the OEM mag, one aftermarket mag, pics of the spent cases and light primer strikes, as well a description of my problems. If I had known better I would have shipped it myself, but I did it thru my local gun store (LGS) and it cost about $75.

Attempt at better photography, lol

I got a call from the LGS about a week later telling me my pistol was back. I opened the box and saw my pistol, my mags, and some paperwork. The problem was a broken hammer, probably from me trying to force the firearm back together. They replaced it, modified the OEM mag, marked where I should mod the aftermarket mag, told me what they had done to fix it, how many rounds they ran thru it and some kind words. I must say even though my experience with the firearm at that time wasn’t pleasant, dealing with MPA made me like their customer service.

Rapid Fire

I took it to the range and ran another 200 rounds thru it, and the MPA ate them up like hot Krispy Kreams. The accuracy continued to stay around 2-3” from the bench but opened up to 5” when hand held. It’s a really heavy pistol not really suited for two hand fire. I added a light and a red dot, but it was still just a range toy. I got notified I had a deployment coming up, so I decide to try an E-Form 1 and Short Barrel Rifle (SBR) conversion. Went to base legal, got a trust made for free (woohoo!!!) and started my wait. I deployed in Jan, filed in early Feb, got approved in early May. Now I had to wait 3 more months to get home and play with my newly legal toy. I started ordering the required parts to turn my giant pistol, into a short lightweight PDW. Here’s the breakdown:

MPA 570SST $560

Another Photography Attempt

Off-Hand Shooting

TRL1 Light $85 Bushnell TRS 25 $90 Pachmayr slip-grip $12 MPA Ar stock adapter $25 Generic buffer tube $20 Minimalist Stock $60 Single point sling $30 3 30 rnd Promags $75 Folding forward grip free (from old project) Form 1 Fee $200 as configured $1132

$865 for just the pistol, stock adapter, tube and stock. Cheapest SBR build I ever seen mentioned. 

Rapid Fire

The new SBR/PDW weights in a little over 6 pounds loaded. At the bench I haven’t been able to shoot tighter than 2” groups, but for my taste, it more than accurate enough for it role. I’ve put about 2000 rounds thru it, and beside the earlier problems, it’s been extremely reliable. I’ve run only FN SS197 and Federal 40gn FMJ thru it, the SBR has been consistency accurate, and I’ve haven’t had any problems since the repairs.

To discuss the role a little, it now fills the needs for my 0-150 yard defensive situations, creating a great Personal defense weapon. Some debate the capabilities of the 5.7x28mm, but the level of accuracy and rate of fire mitigate the “Power Factor” that was once use to determine the strength of a weapon system. **About 1 years later I contacted MPA after seeing their YouTube video on a few fixes. The major fix required cutting the frame and refinishing the exposed metal to reliably disassemble the weapon without tools. At the time I have neither the expertise or the tools to accomplish the task. After a short conversation, Masterpiece Arms asked me to send back my rifle for free factory upgrades. They cut and refinished the frame, throated my barrel for an improved chamber, and correctly (my fault) mounted my stock for free. Like I said, great customer service. Have you built your own PDW? Let me know about it in the comments. Cheers

Most Fun For Around $1000 SBR Market