UTAS UTS-15 Review
Part 5 - Internal Features
October 17, 2013

UTAS UTS-15 Review

In this part of my UTAS UTS-15 Shotgun Review, I show some of the key internal features of the UTS-15 shotgun.  Although, based on the Owner's Manual, it is possible to disassemble the shotgun further than shown below, I chose to keep disassembly to a level similar to that of field stripping.


I decided to keep disassembly at this level for two main reasons.  The first is that the Owner's Manual lists 153 different parts related to this shotgun and it's accessories.  If I started further disassembly, it might not end until all the parts were all in a big pile.  The second reason is that there is no need to disassemble further under normal circumstances and I wanted to ensure the shotgun was in working condition just like someone would receive one from the factory.  The photo below lists all the parts for the UTS-15 and keep in mind that it also lists the individual parts that makeup the accessories.  Also, some parts are joined together in a way that they cannot be disassembled (ex. barrel, barrel extension and barrel hanger are welded together).

Figure 1
UTAS UTS-15 Review Parts List

The Owner's Manual provides a really nice fold-out exploded view of the UTS-15 and each part is identified by the item number and listed in the Parts List above.  With this exploded view, you can get an even better idea on the internal workings of the shotgun.

Figure 2
UTAS UTS-15 Review Parts Diagram

Barrel Assembly

The barrel assembly is actually much more than just the barrel components.  The assembly includes both magazine tubes, follower components, loading port doors, shell feeding mechanisms, top rail and side covers

Figure 3
UTAS UTS-15 Review Barrel Assembly

Figure 4
UTAS UTS-15 Review Barrel Assembly

In reality, the actual barrel assembly is really the combination of the barrel, barrel extension, barrel hanger and barrel studs which are all welded into a single assembly.

Figure 5
UTAS UTS-15 Review Barrel Assembly

Figure 6
UTAS UTS-15 Review Barrel Assembly

These next photos show how the shell stop actually blocks the shells coming down the magazine tube.

Figure 7                                      Figure 8                                      Figure 9
UTAS UTS-15 Review Shell Stop   UTAS UTS-15 Review Shell Stop   UTAS UTS-15 Review Shell Stop

The photo below identifies key components that makeup the feeding mechanisms of the UTS-15.  The components are:

  1. Shell Stop
  2. Interrupter
  3. Right Shell Release Gate
  4. Left Shell Release Gate

In the photo below circled in red, you can see how there is a flat area at the end of the ramp on the shell stop that rests on the edge of the case rim and holds the case inside the magazine.  You can also see that the interrupter (B) is shifted over to also hold the left shell forward and in this position the interrupter also allows the right shell to come fully rearward where the shell is held in place by the right shell release gate (C).

Figure 10
UTAS UTS-15 Review

The photo below shows the legs of the shell release plate (E).  You can also see that the barrel extension is welded to the barrel.  The barrel and extension material are made from 4140 steel which is common for many shotguns.

Figure 11
UTAS UTS-15 Review

In Part 3, I show how shells feed from the magazine tubes to the chamber and then ejected.  In this sequence of photos, I try to show how shells are being selected to feed into the loading ramp area based on the position of the shell stop as the action is cycled.

This next photo represents a state where the left magazine tube is blocked and shells are intended to feed from the right tube.  Since the right shell is in the rear position on the shell release gate, all that is needed is to cycle the action fully rearward to make the right shell eject from the right tube.  For this exercise, I pushed the shell release plate legs by hand to actuate the shell release plate.

Figure 12
UTAS UTS-15 Review

After the right shell was released, the next shell in the right tube is held in the forward position by the shell release gate.

Figure 13
UTAS UTS-15 Review

You can see how the shell is held in the forward position when you look down at the magazine tube.

Figure 14
UTAS UTS-15 Review

When the shell release plates are pushed forward by the action, the next shell in the right tube is allowed to reach the rear position on the shell release gate.  Throughout this sequence, the interrupter has always been pushed towards the left magazine tube and has no real interaction with the right tube.  The sequence of events would be the same (but opposite) if you had the shell stop blocking the right tube.

Figure 15
UTAS UTS-15 Review

These next three photos show the sequence of shells feeding from both magazine tubes.  The photo below shows the left shell in the rear position on the shell release gate and the right shell is held slightly forward of the rear position by the interrupter.

Figure 16
UTAS UTS-15 Review

When the action is pulled to the rear, the left shell ejects, the interrupter shifts to the left, and the ramp of the shell release gate is holding the right shell slightly forward of the rear position.

Figure 17
UTAS UTS-15 Review

When the action is pushed fully forward, the right shell shifts to the rear position and the left shell is held by the interrupter. Overall, I think these feeding mechanisms are clever and relatively simple.

Figure 18
UTAS UTS-15 Review

Stock Assembly

The other major assembly is what I will call the stock assembly.  This assembly is made up the stock, receiver, trigger group, pistol grip and shell elevator which pushes the shells down instead of up.

Figure 19
UTAS UTS-15 Review

Figure 20
UTAS UTS-15 Review

In this next photo you can see the trigger linkage going rearward to the sear.  The safety rotates to block the rear portion of the trigger from moving up as the trigger is pulled to the rear.

Figure 21
UTAS UTS-15 Review

When looking into the "all polymer" receiver, you can see at the rear the hammer and bolt release.  I'm still a little surprised that the receiver is all polymer and only time will tell if this part will be able to handle long term use.  I'm sure UTAS has done some endurance testing and they feel these polymer materials will work. 

Figure 22
UTAS UTS-15 Review

These next two photos show the mouse trap (elevator) in the up and down positions.  Also you can see the steel ejector (circled below) that is embedded in the polymer receiver.

Figure 23
UTAS UTS-15 Review

Figure 24
UTAS UTS-15 Review

Bolt Assembly

The bolt assembly is shown in these next photos.  The bolt body is made from 4140 steel and the rotating head from heat treated 4140 steel.  The rotating bolt head includes three locking lugs which mate up with the barrel extension.  The bolt body has a roller on the right side which is used to push up the mouse trap spoon (elevator) as you cycle the action.

Figure 25
UTAS UTS-15 Review

The steel extractor is spring loaded (like most) and seems to give a decent amount of force to push the extractor against the shell.  Also, the sharp extractor tip seems to get a good grip on the rim of the shells.

Figure 26
UTAS UTS-15 Review

Figure 27
UTAS UTS-15 Review

These two photos give you a good look a the front of the bolt face and the rear of the firing pin.

Figure 28                                                           Figure 29    
UTAS UTS-15 Review   UTAS UTS-15 Review

In this next photo I have pressed the firing pin fully forward with my finger and pushed the bolt face to the rear which rotates the bolt to lock the lugs in the barrel extension.  It is not until the bolt is rotated to this position that the firing pin can contact the primer.  The reason I'm pointing this out is that it is possible to pull the trigger and release the hammer prior to the bolt being locked in place.  Since the firing pin cannot reach the primer until the bolt is locked in place, there shouldn't be any safety issues, but if you pull the trigger too soon in a rapid fire sequence, you may need to cycle the action and eject a live shell to re-cock the hammer.

Figure 30
UTAS UTS-15 Review

Forend & Carriage Assembly

The carriage is machined from aluminum and is bolted to the forend.

Figure 31
UTAS UTS-15 Review

Figure 32
UTAS UTS-15 Review

Figure 33
UTAS UTS-15 Review

Figure 34
UTAS UTS-15 Review

Recoil Pad

The recoil pad is a rubber outer layer on top of a polymer substructure.  The rubber is stated to have a shore hardness of 8 on the durometer A scale.  Not having anything to measure the hardness myself, I think the 8 value seems low because a value of 20 would be a rubber band.  Regardless, there is rubber between your shoulder and the shotgun, but I feel the overall softness of this recoil pad could be improved upon.

Figure 35
UTAS UTS-15 Review

Figure 36
UTAS UTS-15 Review

Figure 37
UTAS UTS-15 Review

Figure 38
UTAS UTS-15 Review

Magazine Cap (Takedown Nut)

The magazine cap is made from aluminum and includes a spring loaded detent pin to prevent it from working loose.

Figure 39                                     Figure 40                                     Figure 41
UTAS UTS-15 Review   UTAS UTS-15 Review   UTAS UTS-15 Review

Upper Stock

The upper stock is an all polymer part that must be in place when operating the shotgun because it acts as a guide for the shells as they are ejected from the magazine tube.

Figure 42
UTAS UTS-15 Review

Figure 43
UTAS UTS-15 Review

Figure 44
UTAS UTS-15 Review

Figure 45
UTAS UTS-15 Review



At first glance the workings of the UTS-15 may appear complex, but if you break down the operation of each component, I feel the mechanisms seem clever and relatively simple.  The two tube feature do add extra parts and that along with the tubes on top of the barrel, plus the bullpup style, make some of the mechanisms seem non-traditional for a pump shotgun.  In reality, that is exactly what you are purchasing when you buy the UTS-15... something non-traditional.

For more detailed photos and commentary, make sure you check out the other parts of this review and feel free to leave comments on my Reader's Comments page.  The following links are provided to help you see other parts of this review. 

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