Semi-automatic versions of sub-machine guns have been on the U.S. market since Auto-Ordnance brought out the Thompson 1927-a1 in the 1970s. Other notable makes include the Uzi Model A which began importation in 1980, and the numerous MAC-10 type guns that began to appear in the early 1980s.
The expiration of the assault weapon ban in 2004 has brought a new generation of semi-automatic versions of classic military weaponry of the world. Many are based on Soviet designs. There are a lot of former East Block guns on the world arms market that can be bought cheap.
Of course functional select-fire guns cannot be imported for the civilian market. So U.S. importers began destroying the receivers of original guns and imported the parts kits. Then gun designers and tinkerers sat down and figured out how to make these things work in semi-automatic.
These semi sub guns (SSG?) are designed to comply with current law. Select-fire open-bolt mechanisms were changed to closed bolt semi-automatic operation. The BATFE must approve any design that skates near the edge of automatic operation.
It must be impossible to readily convert any design to automatic function, either by modification of existing parts or substitution of “readily available” parts. In all truth, these SSG are really new designs that have cosmetic resemblance to the select-fire version. Original stocks, handles, sights, magazines or other parts may be used but significant manufacture of new parts is done.
In addition to semi-auto only function, the new guns must comply with other areas of federal law. A rifle must have a barrel at least 16.1 inches long and have a total length of 26 inches. With most of the existing designs this requires a longer barrel than the original model. Older SMG’s usually had barrels that were six to 14 inches long. The longer barrels on the SSG change the profile quite a bit. Some models, like the British Sten or U.S.M3a1 Grease Gun really look silly with the 16-inch tube.
Handgun versions of guns such as the MAC-10 series can fit the original profile but will lack the collapsible stock. Some of the new designs even have an original folding stock welded in the closed position. This is to give the gun the appearance of the real thing.
In the last few months I have had the opportunity to try out three of the semi-auto sub guns. A Suomi 9mm rifle, PPSh 41 rifle and PPS 43 pistol. The Suomi and PPSh are manufactured by TNW Firearms https://www.tnwfirearms.com. They were ordered for local customers, not to test for this column. That idea occurred to me later.
Finland manufactured about 80,000 Suomi Model 1931 sub-machine guns in 9mm. Production ended in 1944. They were fitted with a 12.25-inch barrel and fire from an open bolt. The TNW semi automatic version fires from a closed bolt. It has a 16-inch barrel and the original barrel shroud was lengthened to cover some of the extra length.
The new gun keeps the unusual operating handle, which is located below the receiver at the back of the action. Magazines were made that hold 30 or 50 rounds as well as a 71-round drum. The Suomi currently retails in the $450 to $550 range.