Stemple Takedown Gun Stemple

STG-W
Stemple Takedown Gun
Stemple -Suomi
Owner’s Manual
STG, Page 1
Breakdown View
Buffer
Unmodified
Stemple 76/45
Machinegun
Receiver
Bolt &
Cocking
Handle
Removable Trunion
Lock Nut
Mainspring
Takedown
Screw
Buttstock
Stock Tang
Trigger
Housing
Assembly
Mag Housing and
Barrel Jacket Assembly (short &
long setups)
In 2003, BRP CORP, along with the help of the original inventor, John Stemple, manufactured the
first Stemple Takedown Gun (STG) setups. These are complete accessory packages for unmodified/
transferable Stemple 76/45 machine gun receiver tubes. These “takedown” systems of interlocking
subassemblies can be easily attached to and removed from the 76/45 receiver. This method of
assembly is ATF approved. These machineguns are fully transferable to individuals.
Finnish KP31-based Setups
The Stemple 76/45 is roughly a 45ACP version of the 9mm S&W 76. The S&W 76 design was
heavily inspired by the Swedish K/Carl Gustov M45. The M45 uses the same barrels and magazines
as the Swedish M37. The M37 is a short-barreled version of Finland’s KP31. Since the Stemple
76/45 drew its roots from the Finnish KP31, it was a natural fit to use original Finnish and Swedish
parts in the Stemple 76/45 system.
Weight: 12 lb
Magazine: Suomi KP31 25 rd, 36 rd, 60 rd magazines, and 40 rd &
70 rd drums
Rear Sight: Finnish KP31 500M Tangent or Picatinny Rail
Barrel Length: 12.5 in., 7.5 in.
Cycle Rate: 750 rpm
Finish: Black
Bipod: Detachable
STG, Page 2
Stemple Takedown Gun (STG) Manual
The STG is a blow-black submachinegun that requires knowledgeable operators. Full and complete
adherence to the following instructions is an absolute necessity for safe and responsible use of the
STG. This system is NOT meant for anyone other than individuals knowledgeable in the safe operation
of machineguns and who have a thorough understanding of automatic firearms. If you are not such an
individual you pose a danger to yourself and those around you by using this system.
The following Suomi parts and accessories
will work with the STG:
• Magazines and Drums
• Slings
• Extractors
• Firing Pins
• Barrels (collar may have to be modified)
• Internal Trigger Housing Components
• Mainspirngs
Spare Parts Manufactured by BRP:
• Sear
• Ejector
• Bolt
• Lock Nuts
• Trunion
• Mag Housing / Barrel Jacket
• Cocking Handle
• Lower Assembly
The Differences Between the Original Suomi and the STG
The STG fires from the open-bolt position just as the original Suomi. The major components of the STG are
mostly Suomi 31. A newly manufactured magazine sleeve and barrel shroud assembly is designed to sleeve
over the STG lock nut and give the appearance of a Suomi barrel shroud. The Suomi bolt has been reduced
in diameter to fit the Stemple 76/45 receiver and hole pattern drilled for a new cocking handle compatible with
the cocking handle slot of the Stemple 76/45 receiver. The Suomi trigger housing has been modified to fit the
76/45 sear opening. The internal components are the same, however the sear is newly manufactured. The
trigger housing system has a 3-position setup: safe, semi, full.
The Essentials of Running The STG:
Following these steps will help you use this system reliably and prevent malfunctions,
dangerous operation, and damage.
1) Following Loading Protocol: Do not retract the bolt until you intend to fire.
2) Correct Ammo: Use full metal jacketed ammo only to ensure proper feeding.
3) Correct Mags & Drums: Drums and mags are not dimensionally consistent; contact
BRP CORP for fitting if necessary. Make sure that each Magazine or Drum locks on
the Magazine Latch and does not rock back and forth in the Magazine Housing.
4) Lubrication: Use lubricant sparingly on the outside edges of the Bolt.
5) Cleaning: When cleaning the STG, pay special attention to cleaning the bolt face,
barrel, and feed ramp.
6) Inspection: After cleaning, fully inspect and reassemble the STG.
STG, Page 3
Safety – Your Responsibility
SAFETY MUST BE THE FIRST AND CONSTANT CONSIDERATION OF EVERY PERSON WHO HANDLES
FIREARMS AND AMMUNITION. This manual is designed to assist you in learning how to use and care for this
system properly.
Only when you are certain you fully understand the manual and can properly carry out its instructions should
you practice loading, unloading, etc. with live ammunition.
If you have doubts about your ability to handle or use this particular system safely, then you should seek supervised instruction. Such personalized instruction is often available from gun dealers, gun clubs or police departments. If none of these sources can help you contact the National Rifle Association. You are also encouraged
to contact BRP CORP for assistance.
The person with a gun in his possession has a full-time job. He cannot guess; he cannot forget. He must
know how to use his firearm safely. Do not use any firearm without having a complete understanding of its
particular characteristics and safe use. Remember: There is NO such thing as a foolproof gun.
Basic Safety List
• A loaded firearm has the potential to kill. Intelligently handled it is safe.
• An accident is always the result of basic safety rules neglect.
• Accident prevention is user responsibility.
• Never point a firearm at anything you don’t want to shoot.
• Before handling a firearm be sure to use correct and undamaged ammunition.
• Be sure your firearm is clean – before loading inspect the barrel to insure it is perfectly clean and free of
foreign objects. Shooting with an obstruction in the barrel such as dirt, mud, grease, lodged bullet or jacket,
residues, etc, can cause barrel bulging and/or rupture.
• Never assume that the chamber is empty, visually inspect it every time you handle the gun.
• Avoid alcoholic beverages or drugs before and during shooting.
• Avoid hard hitting or dropping of a loaded firearm.
• Store firearms and ammunition separately, beyond the reach of children. Be sure cartridge chamber is
empty.
• Thoroughly clean the firearm to prevent corrosion.
• Wear eye and ear protection.
• Firearms Safety Course is recommended.
• Handle it with respect not fear.
STG, Page 4
Operation
1. Loading the Magazines and Drums
a. Magazines
•  There are numerous magazines manufactured for the Suomi 31&37. Make sure that the magazine
fits properly and test its ability to feed using dummy rounds.
•  When filling the magazines, make sure that the rounds are firmly pressed against the rear of the
magazine.
b. Drum
• You may fill the drum to capacity or only load small amount of ammo. The drum operates on a constant force spring otherwise know as a clockwork spring located in a spring cage in the center of the
drum. The spring causes the cage, pusher arm, and base plate to rotate clockwise.
•  Open the drum by pressing the ratchet release pin and rotating the locking arm away from the retaining shoulder.
•  Charge the drum by winding the cage counterclockwise. The ratcheting mechanism will ‘click’ as
you wind the cage. Each ‘click’ is approximately 10 rounds and represents a locking point for the
ratcheting mechanism. Only charge the drum to the point you want to load it. At a certain point, approximately 5 ‘clicks,’ the base plate will start rotating with the cage and pusher arm.
•  Once the cage and base plate cannot rotate any further, start loading the drum bullet tip up. You
will need to do this on a flat surface so the rounds do not tip over. Be very careful not to press the
ratchet release button, it will release the full force of the spring and possibly crack the feed lip.
•  Once full, press the ratchet release button and make sure that there is sufficient force pushing the
rounds toward the feed lip to feed the gun during cycle. Place the cover plate over the drum body,
press the ratchet release pin and rotate the locking arm toward the retaining shoulder.
2. Loading the Gun
•  With the bolt forward insert the drum or magazine into the magazine housing and smack into place
making sure that the magazine catch lever engages the magazine. Pull down on the magazine to
make sure that the magazine or drum is properly engaged.
•  Be careful to not press the magazine catch lever when holding the gun.
3. Firing the Gun
a. Retract Bolt to the end of the cocking track
b. Pull Trigger
4. Unloading the Gun
a. With rounds still in magazine. The bolt is the ‘open’ position. Set the selector is set to the rear
(SAFE). Push the magazine release lever forward and remove the magazine.
b. With empty magazine. The bolt is the ‘closed’ position. Push the magazine release lever forward and
remove the magazine.
Fire Control Selector
(Shown in Full Position)
Fully Forward: Full Auto
1 Click Rearward: Semi Auto
Fully Rearward: Safe
STG, Page 5
Disassembly Procedure
Step 1: Remove the Takdown Screw
• Use the STG Multi-Tool or appropriate screwdriver to unscrew the Takedown Screw (approx. 6 rotations)
STG Multi-Tool
Fitted Takedown
Screw Tip
STG, Page 6
Takedown Screw
Step 2: Remove the Buffer
• Once the screw stops rising from the receiver, hold
the Buffer and pull the screw
upward from the receiver.
Takedown
Screw
Buffer
Rod
• Remove the Buffer.
Mainspring
Buffer
Buffer
Pad
Step 3: Remove the Bolt and Cocking Handle
• Retract the Bolt and Cocking Handle to the end of the Cocking Handle Track, pull the Cocking
Handle out of the right side of the Receiver, and dump the bolt out of the rear end of the Receiver.
Bolt
Cocking
Handle
STG, Page 7
Step 4: Separate the Upper & Lower Assemblies
• Use the multi-tool takedown pin pusher to remove the HK-style takedown pin from the rear of the
magazine housing area. Lift the upper assembly from the lower assembly.
Takedown
Pin Hole
Takedown Pin
Pusher
Step 5: Separate the 76/45 Receiver from the Barrel Jacket / Magazine Housing
Assembly
• Remove the barrel shroud takedown pin by unscrewing the takedown pin retainer, then pushing the takedown
pin out with the multi-tool. At this point the barrel shroud can be removed from the magazine housing.
• Remove the magazine housing by pulling it forward and away from the receiver. Do not twist to remove since
it will scratch the metal finish.
Barrel Shroud
Takedown Pin
& Retainer
Screw
Takedown Pin
STG, Page 8
At this point, no further disassembly is required for
regular cleaning.
Parts to Thoroughly Clean After Any Shooting
All parts listed should be soaked,
brused and/or wiped with CLP until
free of residue.
Bolt Face
Compensator
Barrel: You can run the
cleaning rod through the
rear of the Receiver
Feed Ramp, Rear Barrel Face,
& Ejector
Step 6: Remove the Barrel
• Unscrew the barrel lock nut and pull the barrel from the receiver. You should use the BRP lock nut wrench,
rubber strap wrench, or adjustable wrench to unscrew the locknut. Be very careful not to mar the lock nut.
• You should add a drop of Lock-Tite (blue/non-permanent) to the threads of the trunion to prevent the lock nut
from vibrating loose during use
Barrel Lock
Nut
STG, Page 9
Be careful not to pull the trigger with the selector in
the middle position when disassembled. The sear will
disconnect from the trigger and you may loose the sear
spring & plunger
When separated from the 76/45 receiver, the middle/semi position is only for disassembly of
the trigger pack. Typically, there is no need to disassemble the lower assembly as pictured.
Optional Bipod Setup
To remove the bipod simply unscrew the socket head cap screw
at the top of the bipod and detach from the base.
STG, Page 10
Assembly Procedure
• Reverse operations 6, 5, and 4 until you have
the STG-W as pictured.
• To install the Mainspring and Buffer Assembly:
Be careful to follow these instructions, otherwise, you may bend the mainspring
- Pull the bolt back to the sear catch area.
- With the Mainspring and Buffer Assembled; install the Mainspring into the rear of the Bolt making sure
that it guides into the opening in the rear of the Bolt.
- While pulling back on the Mainspring against the Buffer Block and Buffer Rod, push the BuffeAssembly
forward making sure that the Mainspring continues to guide on the Buffer Rod and rear of the Bolt, and
the Buffer Block guides into the rear of the receiver.
- Once the Buffer Base is at the rear of the Receiver, guide the Bolt forward.
- Grasp the Lower Trigger Housing Assembly and squeeze it to the Receiver.
- Push the Buffer Assembly forward until the holes in the Buffer, Receiver, and Lower Trigger Housing Assembly line up
- Push the Takedown screw through the Receiver until it stops on the Buffer Base.
- Use the STG Muli-Tool or appropriate Screwdriver to tighten the Takedown Screw. (there is no need for
excessive torque)
STG, Page 11
STG, Page 12
STG, Page 13
STG, Page 14
STG, Page 15
Assembly Procedure
Standard Disassembled State
Takedown Keeper
Screw
Alignment & Guide Tool
(stainless steel)
Rear Post
(stainless steel)
The stainless steel Rear Post is semi-permanently fixed to the lower housing. It is threaded and counter-bored to fit the Takedown Keeper Screw.
* Screws and pins with red in-fill should not be removed.
STG, Page 16
Top view of full-auto-only
sear system and Rear
Post
Step 1: Insert the Bolt and Cocking Handle Assembly
Step 2: Insert the Mainspring & Buffer Assembly
To ensure that the Mainspring and Buffer Rod are properly guided into the rear of the Bolt, retract the
Bolt and grasp the Upper Receiver assembly as pictured as you push the Buffer & Mainspring assembly forward.
STG, Page 17
Step 3: Insert the Alignment and Guide Tool
Make sure that the groove on the Buffer Cap is facing down.
Insert the Alignment and Guide Tool through the top of the Receiver. This will retain the Buffer and
Mainspring assembly and maintain rear Buffer and Receiver alignment with the Rear Post.
Step 3: Attach the Upper Assembly to the Rear Post
Takedown Keeper
Screw
Alignment & Guide Tool
(stainless steel)
Guide Pin
Rear Post
(stainless steel)
STG, Page 18
Firmly seat the Guide Pin part of the
Alignment and Guide tool into the top of
the Rear Post.
STG, Page 19
Push down on the Upper Assembly so the
Rear Post Guides into the bottom of the
Receiver and Buffer.
Once fully pushed down, the Alignment and Guide Tool will fall from the top of the Receiver.
STG, Page 20
Step 4: Attach the Rear Keeper Screw (loosely)
Loosely attach the Rear Keeper Screw so the Mag
Housing and Shroud Assembly can slide easily into
position.
Step 5: Attach the Mag Housing and Shroud Assembly
Carfully guide the Mag Housing and Shroud Assembly into the slot at the front of the Trigger Housing
assembly. Make sure that it is firmly seated at the back for Trigger Housing assembly to ensure proper
hole alignment.
STG, Page 21
With one hand, grasp and
squeeze the Upper and Lower
assemblies.
With you other
hand, insert the HK takedown
pin from the right side of the
firearm.
STG, Page 22
Step 6: Tighten the Rear Keeper Screw
Use the fitted multi-tool to tighten the Rear
Keeper Screw. Excessive torque is not
required.
STG, Page 23