Richardson  Receivers


Receiver production has resumed. Call Doug at 310-457-6400

I will be making only Ultimax™ receivers.  I will leave this page up for information and reference.   There will be a lot of changes including a "Tanker" gun featuring a steel receiver and frame and a folding stock, a "Paratrooper" gun featuring an aluminum receiver and frame and a folding stock and my generation 4 semi-auto gun that features a receiver with standard full-auto outside dimensions.   I also plan on offering complete M1A1 gun kits with original Thompson barrels and Ultimax™ receivers with serial numbers to match the frame number. All these are currently in work but do depend on others over which I have no control. 


This particular receiver is an early Colt style with optional (extra cost) square end actuator slot, early Colt markings and serial number. 

As shown, Richardson receivers are completely finished (except for the bolt channel) and look like guns.  Nothing is left for the buyer to do.  Feed ramps are smooth and flat, extractor groove is cut, pilot hole is drilled, rear sight fastener holes are finished and the ejector threads are timed for proper fit of the ejector.


I made my first Thompson receiver in 1957. I was working as a machinist while earning a degree in mechanical engineering at the University of Illinois Champaign/Urbana campus. After graduating with a BSME, I went to work as an aerospace engineer but I never stopped working on the Thompson guns. It was my original intention to put the Thompson back into production. I formed the Universal Precision Corporation to do just that but never got beyond making half size Thompsons which were featured in several magazine articles. It was Ronald Reagan who put an end to that dream by outlawing the sale of new-made machine guns. However, that and the availability of parts kits opened the door to a demand for semi-finished receivers anyone could buy. I do not use the term "80%" because it has no legal meaning nor does it accurately reflect the percentage of completion. It is another company's trade name.  Nor do I use the term "dummy" which is usually used to refer to some cheap chunk of metal or plastic that simply provides a base on which to a attach a few gun parts.

My Thompson receivers are made from steel bars having the same alloy, hardness and tensile strength used in the original guns. The steel is also stress relieved to prevent twisting during machining. This steel has alloying elements that make it easy to machine and produce a smooth finish. The bars are machined on fully automatic, computer controlled machining centers. Computer controlled machining enables edge radii to completely follow the front end contours and to properly radius the 1921/1928 drum slots and magazine cavity edges. To assure the most accurately made receivers, centerline coordinate machining is used with one set-up for all four sides, edge radii and interior in order to eliminate tolerance and error accumulations caused by changing set-ups and reference lines. The quality of these receivers exceeds the originals made by Colt, Savage or the real Auto-Ordnance Corporation (Bridgeport) or anyone else.

I have learned from buyers of my receivers that there are essentially two configurations of receivers wanted. The first is a receiver that appears from all outward respects to be a working original gun receiver. It should accept as many of the original gun parts as possible. Where it is not possible to fit gun parts, the receiver must be able to accept display parts that will make the "gun" appear to be complete and functional. Also, the receiver should not require any additional machine work to assemble the "gun". The second is a receiver as just described but with as many additional machined original gun features as possible so that the receiver can be finished into a working gun exactly like the original TSMGs with the least amount of machine work. And, QUALITY, QUALITY, QUALITY!!!

During the over 57 years of making Thompson receivers, I have probably made every conceivable variation possible. And I listen to my customers. The hugely successful ESF receivers introduced a couple of years ago have under gone some changes to become the ESF+ receivers which more fully meet the above goals.


ESF+™ Receivers

ESF stands for "Enhanced Semi-Finished". ESF+ receivers are available in two configurations as before. The Display™ and the Ultimax™. Ultimax stands for "the ultimate maximization possible of Thompson gun features that can be incorporated into an unrestricted semi-finished non-gun receiver". I have elected to retain the names "Display" and "Ultimax" because they describe the purposes of the receivers so well.

The Display receivers no longer have the rear end section of the bolt channel pocketed out and the sight rivet head countersinks have been deleted. This makes the Display+ receiver more of a display and allows a reduction in price. The Display+ receivers are drilled and tapped from the top side to accept the special sight mounting screws preferred by most buyers of Display receivers.

There are only minor changes to the Ultimax receivers. The Ultimax+ is a Display receiver with every missing Thompson gun receiver machine operation added. The front and back ends of the bolt channel are finished, including the expanded rear section of the 1921/1928 receiver that accommodates the oiler. The breech entry chamfer is finished. Lock ramps and bevels are finished. A new combination sight fastener hole design has been incorporated. It consists of a finished rivet head countersink coupled with a threaded hole. This enables the convenient special sight screws to be used while the receiver is being used as a display and later the threads can be drilled out to accept Thompson rivets. The Ultimax+ is a complete Thompson receiver except that there is a solid section in the middle of the bolt channel. Prior to Ultimax, any machining operation in the bolt channel which could not be completed was not done at all. Those operations would be left for the person who would be completing the receiver. Ultimax changed all that by having every machining operation done at least partially. To do that, Ultimax introduced the concept of "interrupted cutter path machining". This means that a cut that normally starts at one end of the bolt channel and terminates at the other end will be started and stopped as it normally would be in a working Thompson receiver. It is only in the solid middle section that the cut has been interrupted. The bolt channel width has been purposely left slightly undersized to allow a full length finishing cut pass. Ultimax receivers can be assembled as display "guns" exactly as the Display can be.

Features common to all ESF+ receivers include the trigger housing rail walls extended all the way to the rear end of the receiver to increase strength (not applicable to 1921/1928 and can be cut back to TSMG style if desired), the front pocketed portion of the bolt channel has been extended further to the rear to clear the bolt handle hole and slot on all models, a new design Display Bolt Handle is used which clamps anywhere along the bolt handle slot. This allows the bolt handle to be positioned at the front or rear of the bolt handle slot in order to emulate "closed-bolt" or "open-bolt" positions, a new design Display Pilot is used and my Screw-On Grip Mount design has been added to all models as standard with the TSMG design being optional on 1921, 1928. M1 and M1A1 models. All ESF+ receivers provide clearance to enable the trigger housing components to function normally. These changes reflect customer preferences. No ESF + receiver can accept a bolt since there is a solid section left in the bolt channel.

Although all ESF+ receivers can be made into working guns, those who have the license to finish the receiver will find the Ultimax+ to be the best semi-finished receiver available. All of the time consuming and difficult machining operations have been completed. Finishing the Ultimax+ receiver requires removing the solid center section of the bolt channel. But what needs to be done is obvious since every interrupted cut starts and stops as it would normally. It is not necessary to analyze drawings to set cutter positions - just continue the interrupted cuts using the beginning and ending areas as guides. Those building up a display gun with an Ultimax+ receiver have the added enjoyment of understanding how their "gun" was designed to work- it’s all there!

Only one cutter is required to finish an M1-style Ultimax+ receiver. It is a 1/2"diameter, 4 flute, 1-3/8" cutting length, .031" corner radius. ALTiN coated, carbide end mill. 1921 style Ultimax+ receivers require the same cutter plus a special 1" diameter x 1/4" wide x .031" bottom corner radius, M42, ALTin coated, long neck T-slot cutter to cut the side slots. These are the recommended cutters and are offered in the TOOLS page of this website.

ESF+ receivers are available in all standard Thompson models and some additional models of my design. 1921/1928 and M1/M1A1 models are available in both the Display ESF+ and Ultimax ESF+ configurations. The Models 1921 and 1928 are dimensionally identical as are the Models M1 and M1A1. The Models 2M2, 2MM, 2S, M2 and MS are my designs and are available only in the Ultimax ESF+ configuration.

The 2M2 receiver is my redesign of the 1921/1928 receiver. The pilot hole is sized like an M1 but in the 1921/1928 position and the actuator slot is positioned slightly rearward. This receiver is designed to be finished to accept a 1921 or 1928 bolt/actuator/lock assembly but eliminates the oiler which, arguably, never really worked. A modified M1 pilot and buffer (or Richardson 2M2 Pilot and Urethane Buffer) are used for better recoil spring control and true buffering. In my opinion, this creates the ultimate 1921 or 1928 gun because it has all the benefits of the 1921/1928 lock mechanism with the ease of assembly of the M1.

The 2MM receiver is a 1921/1928 receiver except that the pilot hole is sized and positioned like the M1/M1A1 and the bolt handle slot is like the 2M2. It is meant to have a bolt channel identical to an M1/M1A1 except that it has side pockets for weight reduction. This combination enables an M1 or M1A1 bolt, modified to have a top mounted bolt handle (like one of my kits as long as current supplies last), to be used for simple and more reliable (especially with blanks) slam fire operation. This is particularly advantageous to those who wish to make a 1921/1928 style gun with a minimum of time and cost. This receiver combines the best features of the 1928 gun style and M1/M1A1 bolt assembly. It was originally designed as a movie gun but its configuration and simplicity have made it popular with re-enactors and shooters.

The M2 receiver is my redesign of the M1/M1A1 receiver. The bolt handle slot is located on the left side. It uses a standard M1/M1A1 bolt assembly with the bolt handle reversed. It is also available with the bolt handle slot on top like the 2MM. The upper sides are continued forward to the front end to produce a sleeker looking receiver. The nose of the receiver is relieved on the sides below the barrel area to better match both horizontal forearms and vertical foregrips. It is available in two versions: 1) Model M2M has the M1 rear end shape to match M1/M1A1 trigger housings and 2) Model M22 has the 1921 rear end shape to match 1921/1928 trigger housings. It is also available with the top side edges non-rounded in the rear sight area to accept a Lyman adjustable rear sight. This receiver is interchangeable with any TSMG receiver.

For those who want to build a semi-auto gun, I offer my 2S and MS receivers which rely on the Numrich/Kahr (N/K) ATF approved gun design. (There is no approved design that allows a TSMG receiver to be made into a semi-auto.) Like the N/K receivers, these receivers are 1/10" less high than a TSMG receiver. They are interchangeable with N/K receivers. My receivers differ by having a bolt channel that extends all the way to the back of the receiver like a TSMG. This has nothing to do with the gun being semi-auto or full auto. This is done to use the extra bolt travel to absorb the recoil rather than to depend on very stiff recoil springs. It also provides room for a urethane buffer. The 2S and MS receivers also differ in that they are made from the same steel alloy used in my TSMG receivers, the rear sight is properly positioned and the quality is much better. Special Richardson bolt assembly parts are required (but may not be available) for full TSMG-style bolt travel or if a 5/8" spacer is fitted to the rear end of the bolt channel, standard N/K parts can be used.


Markings, Colt square end actuator slot, M1 and M2 variations, sight fasteners, grip mounts, other added parts, services, etc. are at extra cost. Bluing is included.

Display+ receivers: Models 1921/1928 $535,                  Models M1/M1A1 $535

Ultimax+ receivers: Models 1921/1928 $885,                  Models M1/M1A1  $685  

Model 2M2 $865, Model 2MM $750, Model 2S $750, Model M2 $685, Model MS $685.

Aluminum: Any receiver can be ordered in plain high strength aluminum at $45 extra.

No warranty is made regarding the suitability of using aluminum for receivers.  I offer the 1928 Savage aluminum receiver as an authentic reproduction of those made in 1941 for British testing.  The British stated their concern for the possibility of excessive wear on the magazine slots but were not, as far as I know, concerned about the rear end of the receiver cracking.  Although I use the strongest heat treated aluminum alloy available today, I have not tested the aluminum receivers.  I see no problem with using aluminum on any receiver other than the 1921-1928A1 because the designs are so much stronger than the 1921-1928A1s.   




Screw-On Grip Mount

The photo shows my Screw-On Grip Mount both mounted on a receiver (top photo) and unmounted (bottom photo).  Note that the barrel is shown installed in both cases.  That is the advantage of my design.  The barrel does not have to be removed in order to remove the Grip Mount.  In fact, the first thing to do when removing or installing a barrel is to remove the Grip Mount from the receiver.  This tremendously simplifies barreling and eliminates the force applied to the middle of the barrel by the standard TSMG grip mount during shooting.   To use this Grip Mount, the receiver has to be specially made.  All my special receivers (2M2, 2MM, 2S, M2 & MS) accept the Screw-On Grip Mount and will not accept a standard TSMG grip mount.  A standard TSMG receiver can not be made to accept the Screw-On Grip Mount. 







1928 Savage Aluminum Receivers

In 1941 the Savage Arms Company manufactured a number of 1928 receivers in aluminum for the British.  Nothing came of it because the U.S. entered the war and took over all Thompson production.  These receivers are an authentic reproduction.  The price is $45 over the price of the same receivers in steel. 

M2 Receiver With M1 Style Rear End And Bolt Handle Slots On Top And Right Side

M1 Receiver With Additional Bolt Handle Slot On The Left Side.  At Least One Receiver Like This Was Made By Savage.  Seems Like This Would Have Been A Good Idea Because It Allows The Shooter To Choose To Fit The Bolt Handle To Either The Right Or Left Side.

M2 Receiver With M1 Rear End And Fitted With Richardson Display Bolt Handle Kit, Display Pilot Kit And Richardson Combo Rear Sight.

2S (Semi-Auto) Receiver

1928 Savage Aluminum Receiver.  A Number Of  Guns With Aluminum Receivers And Frames And Plastic "Wood" Parts Were Made By Savage In 1941 For British Testing.

RIGHT SIDE 1928 Savage Aluminum Receiver.  A Number Of  Guns With Aluminum Receivers And Frames And Plastic "Wood" Parts Were Made By Savage In 1941 For British Testing






1928 Savage ESF  Receiver

This receiver has the optional cost markings, serial number, Display Knurled 1928 Bolt Handle and Display 1928 Pilot.  The 1928 Savage is interesting because it is the only 1928 not made by modifying a 1921 and was used by the British Commonwealth countries and France.  It was always fitted with a vertical foregrip.  This is not a U.S. Army model.


TSMG parts kits generally consist of all parts of the gun except the receiver. Kits now being supplied often have no barrel or are provided with an inferior aftermarket barrel. However, unlike the other assemblies in the kits, the barrel assembly can not be readily disassembled. Even in the best condition, this assembly requires tools and skill to take it apart. Add 65 years, rust, powder residue and maybe a phosphate (Parkerizing) refinish without the barrel assembly having been taken apart, the task becomes more difficult. And because the grip mount can not be removed before the barrel has been unscrewed, gripping the barrel is difficult, The front sight or compensator must be removed from the barrel and re-installed because it will usually not end up in the vertical position once the barrel has been fitted to a new receiver. For those wishing to avoid all this work, I offer complete barreled receiver assemblies. The price is the sum of the parts. I have discontinued using 3-piece grip mounts and am now only fitting 1-piece grip mounts or my Screw-On Grip Mounts, as applicable.. A receiver, grip mount and barrel must be ordered to create a complete barreled assembly. In the case of compensator or standard front sight, I do not pin either because I do not think it is necessary, the cost is increased significantly and pinning makes it much more difficult to replace the barrel in the future. Add $50 labor charge for barreling. Since I do no custom gun work, I will not fit your kit parts onto a receive


1) Late 1921A Colt: $1641 ($36 HIS)
Price includes late “Colt” pre-Ultimax receiver with 4th pattern markings, Richardson barrel, TSMG 1-piece grip mount, front sight, Display Bolt Handle, Display Pilot and “Colt” ejector.

2) Early WW2 1928A1: $1451 ($36 HIS)
Price includes pre-Ultimax receiver with WW2 1928A1 markings, Richardson finned barrel, TSMG 1-piece grip mount, Display Bolt Handle and Display Pilot.

3) M1A1: $1305 ($36 HIS)
Price includes pre-Ultimax receiver with M1A1 markings, new WW2 surplus barrel, TSMG 1-piece grip mount, Display Bolt Handle, Display Pilot and front sight.


Colt Receivers Fitted With 1921A Barrels And Richardson Early Style Compensators

1928 Savage Barreled Aluminum Receiver

This receiver is fitted with an early Savage type flat 1-piece ejector, Display Bolt Handle Kit and Display Pilot Kit.  Note that this is an Ultimax Plus receiver which allows the bolt handle to be located any where along the bolt handle slot to simulate an open or closed bolt.

1921 Colt Barreled Receiver

The barreled receiver shown consists of a Richardson 1921 "Colt" ESF receiver with 1st Pattern Colt markings, Richardson 1921 Barrel and Richardson 1921 Front Sight.  Only the grip mount is original. 

 Two WWII 1928A1 Ultimax Barreled Receivers 

MS (Semi-Auto) Receiver Fitted With M1 TSMG Barrel And Front Sight And Richardson Screw-On Grip Mount


Early Colt Barreled Receiver Featuring Richardson 1st Configuration 1921 Ultimax Receiver, 1st 1921 Pattern Markings, Colt-Style Ejector; Richardson Barrel, Sight, 1921 Display Bolt Handle & Pilot.



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