Stemple Takedown Gun (STG) U9 Slow Fire (SF) - Adjustable Bolt System

Product Description

U9 Slow Fire (SF) - Adjustable Bolt System

The Slow Fire (SF) utilizes an ultra-smooth adjustable-weight bolt system with hydraulic buffering to dissipate the energy in the recoiling mass during the cycle process.  This is an ideal system for shooters looking to maximize suppressor performance by increasing dwell time in the chamber thereby reducing port noise. The cyclic rates with this system are adjustable between 525 to 900 round per minute.  Shooters can customize their preferred rates simply by adjusting the bolt parts.  At the lowest rate, this gun has a sustained fire of approximately 9 seconds with a 70-rd drum.   The Low-Recoil Bolt System is also used for the 45ACP and 7.62x25. These setups utilize AR pattern stocks, AR pattern grips, and multiple Picatinny mount options for maximum versatility.  

This gun is also ideal for use with a suppressor. The extra bolt weight drastically slows the initial bolt blow-back thereby significantly reducing port noise common in open-bolt  blow-back SMGs.

Transferable

In 2003, the original inventor, John Stemple collaborated with BRP Corp to make new and replacement parts for the Stemple 76/45 receivers he manufactured prior to the 1986 cutoff.  From this came a series of compatible drop-on parts for the unmodified/transferable Stemple 76/45 receivers known as Stemple Takedown Gun (STG) setups.  Since nothing is welded or hand fitted to these receivers, changing setups and replacing parts is fast and easy.  These are the most finely built and smooth running sub-machine guns on the transferable market.  We build them for performance and durability, stock plenty of high-quality spare parts, and provide excellent service.  There is only a limited number of these pre-1986 registered/transferable machine guns remaining, so get one while they last.

Parts and Accessories Included With Each Gun:  1 drum, 1 magazine, multi-tool, choice of barrel and shroud setup  (sights not included) 

If you are going to buy a transferable machine gun for some serious shooting, you should consider the Stemple Takedown Guns for these reasons:

They are ‘new’

Well, the receivers are nearly 40 years old but the Stemple Takedown Gun (STG) setups are complete new parts packages installed on unused pre-1986 transferable Stemple 76/45 machine gun receivers.

Simple / Durable Design

Our guns are very difficult to break and very easy to fix. They are simple blow-back guns and very smooth-running in long full-auto bursts. Some of our customers who own the 9mm guns liken the full-auto performance to a laser beam.

Customizable

The quick-change barrel system allows for a large variety of shroud and barrel options.   By using Picatinny rails (MIL-STD-1913) for sights and hand guards, shooters can add a variety of accessories and optics.   The configurations with the Adjustable Bolt System use common AR pattern stocks and grips with hundreds of options currently available. 

Easy-to-Replace Parts

There’s nothing on these guns that can’t be easily replaced.  We designed this system to protect the registered receiver from any wear during use.  The only parts that can wear can be easily replaced without the need to ship the gun back and forth.

Available Service

If you need service, we are here to support our products.

Shoot Cheap Ammo

We typically just shoot steel-cased ammo. Our milled steel trunions easily deal with potential wear issues from any type of ammo.

Capacity and Control

These guns use 70 round drums and are smooth cycling, accurate, and comfortable to hold.  It's basically an assault rifle with a sub-caliber setup... a very controllable and accurate gun in full auto.  It's so smooth due to the weight, layout, and action; you can actually watch your target being hit through a 4x scope while shooting long bursts.  The 'laser beam' performance of this gun makes it one of the most enjoyable full auto guns you'll ever shoot.

Can't Get Too Hot

These are ideal for machine-gun shoots. The low-pressure pistol ammo cannot create enough heat in the barrel to cause a malfunction or damage the gun.  There's no gas system to clog, and the open-bolt system negates any cook-off risk.

U9 (SF) Data:

Nickel Boron Plating Aluminum Parts and Bolt

Select-Fire with Quick-Change Barrel

Ultra-smooth adjustable-weight low-recoil bolt system with hydraulic buffering 

Cycle Rate: 550-800 adjustable 

Magazine: Suomi KP31 25 rd, 36 rd, 50 rd magazines and 40 rd & 70 rd drums

Nickel Boron Plated Bolt and Mag Housing

Weight: 9.3 lbs

Barrel Length: 10.35" threaded .578"-28, 1/2"-28, or 3-lug setup to use common suppressor. 

Other barrel options: 12.75" (unthreaded) and 8.5" (threaded 1/2"-28 or unthreaded) 

Options: (Chart)

• U9 Lower Housing (no charge) or STG34 Lower Housing (+350).  
• Hook or Round Charging Handle (no charge)
• Aluminum Shroud in NiB or Steel Shroud  (blued or parkerized finishes available) (no charge)
• U9 Mag Housing: Steel or Aluminum (anodized) or Aluminum (NiB) (no charge)
• Switch to Law Tactical Folding Stock Setup: + $190  

Common Add-Ons (Discounts Available with Gun Purchase):

• Add 12.875" Heavy Barrel (not threaded)
• Add MG08 Pattern Spade Grip Kit: (only works with the standard U9 Lower Housing, not the STG34)
• Add extra bolt 9mm
• Add extra bolt 45 acp
• Add extra barrel with 3-lug adapter
• Add extra barrel 45 barrel threaded 5/8”-24
• Add extra 9mm barrel threaded .578”-28
• Add extra mainspring
• Add RF-0 fast fire buffer assembly (for use with 9mm only) with ACE folding stock system
• Add short Steel Shroud (blued or parkerized finishes available)  shroud setup with 8.6" barrel threaded 1/2"-28 or unthreaded 8.3” barrel

Product Update Notes

2022: We introduced the new Internally Threaded Pattern (ITP) assemblies of the Stemple 76/45 receivers to offer a more streamlined and versatile system with enhanced compatibility among setups.  Per this previously approved method of attaching the trunion, separate trunions and bolt guides are no longer necessary for converting between the standard and heavy bolt systems. While these can still be used on the receiver, one trunion now does it all.  For example, the previous U9 conversion to the U9 slow fire setup required separate trunions/bolt guides, bolts, stocks, and buffers.  In the ITP setup only the stock and buffer assemblies are switched to add mass to the moving parts for lower cycle rates.  The bolt and trunion are unchanged.  The fire controls, stocks, and mag housings are also unchanged.  

The conversion from the U9SF to the U45 in the combination guns is also further simplified by having a much heavier 45 bolt so a second bolt extension is no longer necessary to reduce the cycle rate.

The STG1928 parts are also fully compatible with this setup. 

(See Product & Setup Chart)

2023: We switched to NIB-X® Nickel Boron Technology plating by WMD Guns (dark gray color) on the lower assembly, magazine housing, and barrel jacket. This high performance finish adds greater durability and ease-of-cleaning compared to the black anodized finish commonly used on most guns like USGI M16s. Also, the we made the aluminum parts used in these guns from the best 7075 alloy on the market rather the weaker 6061 alloy commonly used on many gun parts.