MechTech

Carbine Conversion Unit

What is the CCU system? The CCU system is an 'upper' piece of an autoloading pistol. The picture below is what is called the "BASIC UNIT". By combining this unit with your pistol 'lower' you will create a pistol that will fire. Currently BASIC UNITS are only available for the Glock and 1911 pistols; however, others will soon be available. Any number of accessories can be added to the BASIC UNIT such as sights, rail systems, and shoulder stocks. Because the BASIC UNIT is not an a firearm you do not need any special licensing to purchase one. Under the federal law, BATFE, it is completely legal to install a pistol lower, remove it, and then reassemble the pistol. (please see the FAQ page for details)

A close up of the barrel on a rifle
Basic Unit

The picture above is a Glock Upper 'BASIC UNIT'. This unit is made of a 16+" barrel, recoil spring, internal slide, cocking handle, and everything you see externally. The basic unit does not need special licensing to purchase because it is NOT a firearm. What do you need to use the BASIC UNIT? A Glock or 1911 pistol. What do you need to do? You need to separate the 'top end' assembly from the frame or 'lower', this is known as field stripping. The picture below is a Glock that has its 'top end' removed.

A gun that is in the shape of a pistol.
Glock pistol 'lower'

By sliding the pistol lower in the upper 'BASIC UNIT' you will create what you see in the picture below:

A black and silver shotgun with a short barrel.
Assembled unit- ready to fire!

Once it is assembled you have a pistol with a 16+" barrel 'top end'. At this point the unit is prepared to fire! All you need to do is slide in a loaded magazine, load a round in the chamber- by pulling the cocking handle to the rear and releasing it. The new unit operates in semi- auto mode just like the pistol does with its original 'top end' installed. You do not need to make modifications to the 'lower' pistol and no unusual harm is done to the pistol while using the upper. You can reverse the assembly whenever you want to. You can customize the unit by adding the various Mech Tech accessories that suit your needs, including shoulder stocks. At no additional charge Mech Tech will install the accessory rails you want on your unit (only applies to new purchases). Our accessories that attach to the rails such as lights, sights, etc, are very easy to install. Please see our accessories page to see what we have available!

Frequently Asked Questions

Technical Specifications

Full specifications
About interchangeable stocks for the CCU
Mech-Tech CCU in competetive shooting
Selecting ammunition for your CCU
1911 CCU in 9mm Luger caliber

Full specifications:
Barrel:
- 16.25 in Stainless Steel
- Button Rifled - 1 Turn in 16" Right Hand Twist - all Models and all Calibers

Weight (basic unit only):
- Approximately 5.3 lbs

Overall Length:
- Glock:

Fixed Stock:
33.29 in
Telescoping Stock:
Min. 24.92 in; Max. 33.42 in
M4 Style Stock
Min. 29.25 in; Max. 32.38 in

- 1911:
Fixed Stock:
32.38 in in
Telescoping Stock:
Min. 24.00 in in; Max. 32.50 in
M4 Style Stock
Min. 28.34 in; Max. 31.47 in

Weaver Style Sight

Straight Blowback Action

About interchangeable stocks for the CCU
Older CCU's with the welded-on fixed stock may be upgraded to accept the interchangeable stock system. You need to order a Retrofit Housing Kit. The kit comes with a new buffer assembly and a new housing configured to accept the interchangeable stock system. On the 'MANUALS/PRICE LIST' page you can see the 'INSTALL STOCKS.pdf' for more details on how the new stock system works. Also note that the new design housing has a square front. Mech Tech will supply a filler plug which slips over the barrel to bring the retrofit cosmetically up to date. if your barrel has a muzzle dec fitted, the filler plug will not slide over the barrel. Contact Mech Tech and make arrangements to send in just the barrel for dec removal and reinstallation - this will be free of charge but you must pay the return shipping.

Mech-Tech CCU in competetive shooting
It seems that the Mech-Tech CCU is finding its way into the competitive shooting sports! We understand that it meets power factors suitable for the 3-gun events. An article in Front Sight magazine, organ of the USPSA, indicates the presence of the Mech-Tech unit in PCC events (July/August 2001 - pg.10). It makes sense of course to use a familiar grip and trigger pull for long gun shooting. This eliminates some important variables when making the switch. The power gains available from the 16+" barrel are significant. The CCU is designed with a special long-lead chamber which reduces peak pressure by about 25%.

Selecting ammunition for your CCU
There are certain factors to consider when selecting ammunition for use in the CCU's. The CCU is a 'blow back' type action. The main design element in a blow back is the weight (mass) of the bolt. This must be chosen to anticipate the 'hottest' loads encountered. The physics of a blow back action is such that the bolt mass and the bullet weight (mass) work together to limit the amount of the case which is allowed to move out of the chamber while the bullet is still in the bore. When the round is fired two things happen immediately:

  • the bullet begins to move out of the case mouth and up the bore
  • the case begins to move to the rear pressing against the breech face.

To elaborate, the case acts like a piston pushing out of the chamber to the rear and the only thing limiting the amount of movement of the case is the mass of the bolt - contrary to popular belief the recoil spring plays a negligible role in the initial case movement. The real design issue is to limit to a safe value the distance over which the case moves to the rear out of the chamber over the time that the bullet is still in the bore. As long as the bullet is in the bore the gas pressures are high and the case must have sufficient support to prevent case head blow-out or other pressure signs. The bolt weight in the CCU is enough for a good safely margin and as such the ammunition needs to be powerful enough for reliable ejection. 'Target' loads generally are not 'hot' enough. One should use the hotter factory loadings especially in 9mm where a +P loadings are best.

1911 CCU in 9mm Luger caliber
The 1911 CCU in 9MM usually requires no modifications for proper function. However, if you experience ejection problens then you may need to install a 'long finger' ejector in your pistol frame. We have found that EGW manufactures such an ejector and in most cases it can be installed onto a 1911 frame by a competent gunsmith at little cost. Mech-Tech Systems has the EGW ejectors for purchase if your pistol does not eject shells properly using our CCU. The ejectors are also avialable from Brownells - 641-623-8059 (p/n 296-100-038) or contact EGW directly at 215-348-9892 (p/n 'XL EJECTOR .38').

NOTE: for those less familiar with how to download/save these files the following is provided. As stated above, you will need to have Acrobat Reader installed on your computer. When you click on an item in the above list the file will open automatically in your Acrobat Reader application. At this point you can simply view or print the file. To save the file on your computer, use the 'save a copy' icon near the upper left in the Acrobat Reader tool bar. The 'save a copy' window will open and here you can select a folder into which you want to save the file. At the bottom of this window you can also rename the file (in the 'file name:' bar) to whatever you want. Then click the 'save' button at the lower right of the window and you are done. You now have a copy of the file on your computer in the folder you selected and by double clicking the file name it will automatically open in Acrobat Reader where it can be viewed or printed off-line. You will notice that Acrobat Reader will sometimes display the pages rotated 90 degress - not handy to read. Use the keyboard 'ctrl' and 'shift' keys pressed simultaneously followed by the minus ' - ' key to cause a 90 degree rotation. Repeated operation of the minus ' - ' key while holding down the 'ctrl' and 'shift' keys will cause successive 90 degree rotations of the text.

Warranty
WARRANTY APPLIES ONLY TO THE ORIGINAL OWNER. For one year from the date of purchase. if the Mech-Tech Systems CCU is operated and maintained according to the instructions in the owner's manual, Mech-Tech Systems will repair or replace, free of charge any part found to be defective in material or workmanship. Customers are responsible for freight charges for returning products to the factory.

THIS WARRANTY DOES NOT COVER:

  1. ITEMS WHICH BECOME WORN DURING NORMAL USE
  2. REPAIRS DUE TO OPERATOR ABUSE, NEGLIGENCE, ACCIDENT OR FAILURE TO OPERATE AND MAINTAIN ACCORDING TO OWNERS' MANUAL
  3. UNAUTHORIZED MODIFICATIONS TO THE CCU