View Full Version : Any info on a "roller locking" autoloader mechanism?

Mike P. Wagner
January 29, 2001, 10:41 PM
"Unlike the Makarov, the CZ-52 does not use a straight blowback mechanism. Because of the high power of the cartridge, the CZ-52 has a rather complicated, but strong, roller-locking mechanism." - makarov.com

Is there any information on the web that would explain how a "roller locked breech" works? I found an animated .gif a while ago that made the operation of a 1911 crystal clear. Is there any such animation for roller locking?



January 29, 2001, 11:56 PM
None that I've seen that used the CZ-52 as an example. Over at http://www.hkpro.com they have quite a bit regarding the roller locked setup on HK long guns.

Badger Arms
January 30, 2001, 12:07 AM
Okay. The bolt is made in two pieces. The front of the bolt is conventional. The rear of the bolt essentially acts as a bolt carrier does in the AR-15 rifle. The rollers are pushed outward as the bolt closes. When the weapon fires, the rollers, in order to move inward, have to move the rear half of the bolt rearward before the front of the bolt carrier can move rearward that much. It is not really roller locked but roller delayed locking as the bolt is never truly locked. To prove this, you can stick a dowel down the barrel of the gun and press hard enough to open the gun. Really good pictures are available in "Small arms of the World" and I think on HKPRO.com also.

Badger Arms
January 30, 2001, 12:12 AM

There are six points of tangency in the HK roller locking system:
A = Two entry points on rollers for energy.

D = barrel extension. Receives 75 percent of the energy. Points B and C are absolute maximum theoretical limits.

C would be no delay, straight blowback.

B means the gun would not open.

Points E receive the remaining 25 percent of the energy and create the necessary delay.

Courtesy of HKPRO.com... Check it out.

January 30, 2001, 09:53 PM
Roller locking is solid and reliable, but one
of the disadvantages is that the system does not
provide a means of "primary extraction" (i.e. breaking
the initial seal of the fired case in the chamber by the
bolt rotating to unlock). As a result, they need
a fluted chamber to ease extraction.

Badger Arms
January 30, 2001, 11:55 PM
True about fluted cylinders but only with high pressure cases like the .308, not with conventional blowback cartridges like the 9mm, 45, 7.62x25, etc.

January 31, 2001, 11:34 AM
The CZ-52 is one of the strangest pistols I know (the wierdest one I own). It uses VERY complex and expenssive reoller locking mechanism similar to HK rifles.
When you take the slide apart ro cleaning, it breaks down to like 12 pieces without even doing the detailed strip.
The guns is said to be "one of the strongest semiautos ever made" which is possible, judjing by the porking pressure of SMG 7.65x25 round it uses.
The ergonomics of the gun is similar to riding characteristics of pregnant cow, but the guns is fairly accurate.
It is one of the best deals on the market, because you are getting an unususl and possiblu collectable pistol in exellent condition for only $120-$140.

January 31, 2001, 11:53 AM
Calico 9mm series is another small arm that uses roller lock mechanism (I heard that they get the patent from HK?!?). Anyway, there is no flute in the chamber and there is no extraction problem for me so far. :)

Marko Kloos
January 31, 2001, 10:58 PM
Another pistol that incorporates the roller lock system is the Heckler & Koch P9S series. It was available in 9mm and .45 ACP, it incorporated polygonal rifling, and the P9S series pistols are very accurate and fun to shoot. The P9S was also the first commercial pistol to use polymer for more than just grip panels...the trigger guard and lower dust shield were made of tupperware.

Badger Arms
January 31, 2001, 11:41 PM
You are correct. Read my above post. Only high-pressure rounds like the .308 or .223 require fluting.

James K
February 1, 2001, 12:36 PM
Hi, guys,

"Roller locking" is not really locking. It is a form of what is usually called "retarded blowback", where the barrel and breechblock are not truly locked, but where the blowback is delayed until pressure drops.

The roller lock system is something of a "tour-de-force"; it is quite complex, and requires precision workmanship. It is notable that the TT-33 fired the same 7.63x25 cartridge with no problems using a cheaper, lighter, and more conventional Browning dropping barrel mechanism. The only advantage of "roller locking" in a pistol, which is more theoretical than real, is that the barrel can be fixed for greater accuracy. In practice, the barrels are not really fixed and even this advantage is somewhat reduced.


Mike P. Wagner
February 1, 2001, 04:28 PM
"It is notable that the TT-33 fired the same 7.63x25 cartridge with no problems using..."

If I understand correctly, and I'm learning about this weapon, part of the motivation for this mechanism is to fire hotter loads than can be fired from the TT-33. I think I've seen warnings not to try and fire some of the CZ-52 loads in a TT-33.

Is this correct?


February 1, 2001, 04:49 PM
IIRC, the roller locking originated on the MG42, not an original HK idea at all but one they (borrowed/stole, pick one) from Mauser when they left. As Jim said, it is properly classified as retarded blowback, just like the M1921/28 Thompson.

February 1, 2001, 05:36 PM
Actually, the HK MP5 SMG (roller locked) in 9mm Para has a fluted chamber. So does the HK P7M8 (not roller locked, but
gas delay blowback). Maybe it is not required, but
is makes extraction easier.

April 29, 2001, 01:47 AM
A friend of mine has a CZ-52 which unfortunately broke (in what must be a fluke, since other people have reported that the CZ-52 is a very durable pistol). Contrary to what some have said here, it appears to be a true locked-breech design; the only reason pushing back on the inside of the breech with a pencil will unlock the action is that the barrel itself travels back with the slide. While the figures may accurately depict the HK's lockup mechanism, the CZ's is different.

One feature of the CZ-52 is that the barrel's movement is entirely parallel to its axis (as with the Broomhandle Mauser, the Luger P-08, the Walther P-38, and the Beretta 92). By contrast, most locked-breech pistols tilt the barrel as part of the lockup operation.

April 29, 2001, 04:16 PM
The 7.62x25 Tokarev round is NOT the round that the CZ-52 was designed to fire.

The 7.62x25 Czech round is much hotter than the Tokarev cartridge and is unsafe in the Tokarev pistols. Unfortunately, there is no good source of the original Czech round on the market.

BTW, there is some dangerous milsurplus 7.62x25 ammo on the market that will blow up even a CZ-52.


April 29, 2001, 05:47 PM
Sounds like the old Llama Omni 9x19 semi.....

Mike Irwin
April 30, 2001, 02:59 PM
If I understand correctly, and I'm learning about this weapon, part of the motivation for this mechanism is to fire hotter loads than can be fired from the TT-33. I think I've seen warnings not to try and fire some of the CZ-52 loads in a TT-33.

Is this correct?


You're correct. The 7.62x25 loads as loaded by the Czechs for this pistol are CONSIDERABLY hotter (up to 25% greater chamber pressure) than the 7.62x25 Soviet rounds used in the Tokarev TT-30/33 pistols.