This upper receiver is designed to be used with the SWD M-11/9
submachine gun. NFA (National Firearms Act, Title 26, United States Code)
rules apply to its use and possession.
It is the owners/users responsibility to comply with all local, State and
Federal laws and regulations in the use of this product.
Possession of this upper receiver with a semi-auto M-11/9 lower receiver is illegal and potentially dangerous.
MAX-31 mk2 Upper Receiver
The MAX-31 mk2 upper receiver is specifically designed to allow use of inexpensive, high capacity, 72 round Suomi M31 drum magazines.
The longer receiver converts the M-11/9 into a carbine sized submachinegun and provides greater control and handling.
The 72 round drum magazine allows you to shoot longer between magazine changes, enabling you to save precious time during matches.
Features include a 18-1/8" long accessory rail on top and hard mount points for additional M1913 rails on right and left side of front
handgrip. Bottom rail is integral. Contained within the upper receiver is a heavy weight bolt assembly with a longer length of travel
than the stock M-11/9 upper receiver . This reduces the rate of fire (ROF) from 1,100 RPM down to around 770 RPM. Due to the reduced ROF
and longer bolt travel, muzzle rise is reduced, the gun feels much smoother in operation and easily stays on target. The MAX-31 mk2 attaches
to the stock M-11/9 lower receiver without any modification to the lower receiver and uses your existing retaining pin. 50 round M31
"Coffin" magazines can also be used with the MAX-31 mk2, but the 36 round double feed magazines are not compatible.
The picture above shows a MAX-31 mk2 with additional Lage Mfg. accessories that are not included with the MAX-31 mk2 upper receiver.
Registered lower receiver is not included.
- Designed for use with a M-11/9 submachinegun lower receiver.
- Requires no modification of the lower receiver to install upper.
- Uses Suomi 72 Round Drum Magazines and 50 round "Coffin" magazines.
- 8-3/8" barrel threaded 1/2-28 at muzzle with "Birdcage" flash suppressor. Other barrel threads available.
- 18-1/8" long accessory rail along top for mounting a scope or removeable iron sights.
- Integral 5-1/4" bottom accessory rail.
- Mounting points on left and right side of foregrip for mounting additional rails.
- Side cocking, non-reciprocating, spring return charging handle on left side.
- Ambidextrious "Paddle" magazine release.
- 770 RPM rate of fire. Optional 830 and 840 RPM with use of VBS. Rate of fire with Federal 115 gr. Ammo is 670, 710 and 800 RPM.
- No modification of the magazines is required.
- Overall dimensions of MAX-31 mk2 upper recevier:
- Length: 21"
- Width: 1-1/2" (2-1/4" across cocking knob)
- Height: 4-11/16"
- Weight: 4 pounds
- Overal dimensions of the MAX-31 mk2 when assembled to an M-11/9 lower receiver with a 7-1/2" stock:
- Overall length with 7-1/2" stock- 28-1/2"
- Height- 6-1/2"
- Width- 2-1/4"
- Weight unloaded is 6 pounds, 2.5 ounces
- Weight of 72rd Drum Magazine: 2 pounds 2-1/2 ounces
- Rate of fire:
- Winchester White Box 115 Gr. FMJ- approximately 770 RPM
Optional Rates of Fire with Variable Buffer System (VBS):
One VBS Spacer installed- 830 RPM
Two VBS Spacers installed- 840 RPM
- Federal 115 Gr. FMJ- approximately 700 RPM
One VBS Spacer installed- 710 RPM
Two VBS Spacers installed- 800 RPM
- Different bullet weights, such as 124 gr. And 147 gr. , as well as lighter or stronger
powered ammunition, will result in slower or faster rates of fire. The rates of fire
above are approximate. The rate of fire of your ammunition may vary.
Steel cased ammo is not recommended. Use of reloaded/re-manufactured ammo will void the warranty.
Note: All prices are subject to change without notice.