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)

Basic Unit
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.

Glock pistol 'lower'
Glock pistol 'lower'

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

Assembled unit- ready to fire!
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

Is is legal to convert the CCU back to the original pistol?

Yes. The BATFE recently published a ruling which clarifies this - here is the link:
There has been a lot of missinformation circulating to the effect that once the pistol lower has been asembled to a rifle configuration then converting back to the pistol constitutes 'making a pistol from a rifle' and thereby placing the pistol into the SBR (short barrelled rifle) class. Not so. Please see our Forum for even further clarification. It is the first post on the Forum so you don't have to spend time trying to find it.

Do I need an FFL (Federal Firearms License) to purchase this product?

No. The CCU is not a firearm and will not fire without a pistol lower in place. The CCU is simply an accessory such as a scope or grips. For State and local laws you are advised to become aware of them relative to where you live. As far as Mech-Tech is aware, the CCU in and of itself is legal in all States. We do know that in the case of California the combination of the CCU and a pistol lower becomes illegal under current law. If and when Mech-Tech becomes aware of any other special circumstances such as California, we will publish this information. Again, the customer has the responsibility to determine the legality of the combination in their circumstance.

I have an older CCU with a welded on fixed stock. Can this be removed and the housing modified to accept the interchangeable stock system?

The best solution is 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.

Are CCU models available for pistols other than what is shown on this website?


Can the CCU be modified to fit pistols other than what is indicated on this site?

No. The CCU's are quite pistol specific.

Can I order directly on the internet from this site?

No. Our online store will be up and running very soon. For now, use our CONTACT page to place an order.

Can I order parts for my CCU?

Yes. You can order as many parts as you want. There have been certain design changes over time and we need to determine which revision you have. Please contact us for details.

Can I shoot .45 ACP ammo in my .460 Rowland CCU?

Yes you can but there are some things to observe. The 460 case is 0.060" longer than a 45ACP and because of this the 45 round actually 'headspaces' on the extractor claw which leaves space between the 45 case mouth and the headspace ledge against which the 460 case rests. Firing 45ACP rounds will cause a buildup of crud between the 45 case mouth and the headspace ledge. This must be carefully cleaned out before attempting to fire 460 rounds or there will be chambering problems with the 460 round.

Can I shoot .45 Super ammo in my CCU chambered for .45 ACP?

No. Certain modifications are necessary to allow safe use of .45 Super ammo. Please contact Mech-Tech for details. NOTE: - we do not offer .45 Super modifications for Glock CCU's chambered in .45 ACP.

Does the 'basic' unit include any accessories or stocks?

No. The customer needs to specify which items are wanted to add to the basic unit. The basic unit is however fully functional and will fire safely without any additions. Because there is so much variation in what customers want, Mech-Tech has arranged things so that a customer can 'build' a CCU just the way he/she desires.

If I order accessories such as the Quadrail at a time after I purchased a CCU, can I get the factory to install these?

Yes. You need to contact us (see 'CONTACT' page) and make the necessary arrangements.

I live in California - can I legally purchase a CCU?

Yes - recent CA court decisions and the 'california code of regulations' [CCR 11 paragraph 5469 (a)] allow a properly configured CCU to be legal.
'Properly Configured' means a magazine which requires a 'tool' to release it and a min. overall length of 30". On our forum there is information on how to make a 'bullet button' magazine release.
Please see our Forum ander the 'California Legal' topic for more details.

Can I order a Glock CCU in .460 Rowland caliber?

No. We do not offer this.

Can I print out the price list, check off what I want and send it to Mech-Tech as a prepaid order?

Yes - but there are some concerns. You will need to send certified funds (cashiers check/money order). You need to carefully specify the model you want. You must still contact Mech-Tech to get the shipping charges and determine if we have what you want in stock.

Can I get Mech-Tech to thread the muzzle?


Is the Muzzle Dec threaded onto the muzzle?

No - it is pressed onto the muzzle.

How do I remove the Muzzle Dec?

The Dec must be machined off carefully.

What kind of accuracy can I expect?

This depends on so many variables beyond the control of Mech-Tech that we do not specify a number. The CCU is not intended to be a bench rest rifle but there are many units being used in various competitive sports with great success.

1911 9MM and 38 Super CCU's using 45ACP lowers?

You can use a 1911 45ACP (or 10MM & 40S&W) lower with 9mm and 38 Super CCU's but it may require a change of the ejector on the 1911 lower. On some 1911 lowers a slightly different ejector is used for the 9mm and 38 Super cartridges. If the particular lower you want to use with a 9mm or 38 Super CCU causes drag on the CCU bolt then a change in the ejector on your lower will be necessary. This is an easy fix and the 9mm/38 Super ejector will work fine with 45ACP/10MM/40S&W cartridges with the original pistol reassembled.

For new orders are accessory rails factory installed?

Yes. Factory installation of accessory rails is free on all new orders. When you order the rail systems at a later time you will have to install them yourself or make arrangements to have Mech Tech do this. Complete instructions are available in the manuals on the 'MANUALS/PRICE LIST' page.

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:
- 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 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.