Bob Dunlap is a renowned expert on most of todays and yesterdays important AND obscure firearms. He has been a warranty station for most manufacturers, both large and small. His understanding of the design, function, and repair of firearms in general is unsurpassed, and his appreciation of European and exotic arms is legendary among his students. The H&K series of roller-locked military assault rifles and their semi-auto counterparts were an extremely successful evolution of a Polish idea, brought to fruition by both the Germans and the Spanish. The guns have been imported to the U. S. in big numbers since the mid-80s. This course is designed to help all of you owners who love the gun, but are a little mystified about its workings. In typical AGI fashion, we use a cut-away gun that allows you to actually see how the various parts work and interact.

If you want the quick course on how to get this Teutonic meisterwerke rifle apart, back together, and operating as intended, then this course is for you (if you want the long course, look into our basic 108 hour Professional Gunsmith Course.)

Among the items covered are:


  • The Wehrmacht found the original roller locking design in the Radom plant in Poland after they invaded. They liked the design as well as Bob does. They developed the system and used a forebear of the current system in the G-43.
  • The Germans had some problems with the gun involving headspace and tearing the rims off. The design engineer in charge of the project decided to take a vacation in Spain to relax and clear his head. He got so relaxed he did not go back home
  • After the war he went to work for the Spanish CETME group and continued to develop the rifle
  • SIG in Switzerland and Heckler & Koch in West Germany were also working on the design
  • CZ-52 uses roller locking as well, but not delayed blowback
  • System does not require a bunch of stuff like pistons, gas tubes, etc., hanging from the barrel, all forces are in a straight line so the guns tend to shoot well (accurately)
  • See the chamber fluting, and why the system tends to be self-cleaning
  • System also tends to compensate for cartridge length variances (headspace)
  • Roller locking system seems to be becoming pass
  • Guns seem to have less recoil than other systems

Design & Function

  • Roller locking system described and shown
  • How the system compensates for varying cartridge lengths
  • What controls headspace, and how to cure excessive headspace
  • Why you probably should not do it yourself
  • Why the extractor of a roller lock rifle needs to very robust, and why its hook must not be negative
  • The fire control group is very much like that of the .30 M1 Carbine
  • Demonstration of how the sear moves fore and aft, as well as rocks, and explanation as to why
  • Demonstration of how the sear works as its own disconnector
  • Since the safety only blocks the movement of the trigger, it is not positive. How it can be overridden if the system is negative
  • Demonstration of the ejection cycle, how the rearward movement of the bolt raises the ejector, and why the ejection is so violent
  • What mashes up the brass
  • Demonstration of the locking system in the gun with the carrier locked up
  • Why this gun does not have a standard style operating handle attached to the bolt or carrier
  • How the camming action of the operating handle releases the bolt and carrier from engagement
  • Why the locking system can go 150,000+ rounds without appreciable wear but the sheet metal receiver will develop stress cracks


  • Extensive disassembly, and instructions on how to take apart those parts/assemblies not disassembled, such as the recoil spring guide and operating handle. Parts not removed have the reason for that explained
  • Field stripping the gun
  • Operating handle details
  • Magazine catch and rear sight details
  • Bolt assembly, rollers, and extractor
  • Spare parts
  • Safety features and firing pin
  • Trigger group details, how to take it apart, but why you probably do not want to
  • You get a good look at how the various parts fit together and interact (particularly the springs) as Bob explains things

Cleaning & Lubrication

  • AGI cleaning & lubrication methods shown, along with the reasons for their use
  • Ejector disassembly
  • Cleaning
  • Lubing the Bob way, and what kind he likes
  • Trigger housing reassembly
  • Bolt reassembly
  • Bolt carrier reassembly
  • After cleaning, dry with air gun, or in the oven on Warm ~185-200 degrees (metal parts ONLY)


  • Bolt insertion
  • Forearm assembly
  • Trigger housing insertion
  • Buttstock assembly
  • Final thoughts


  • Magazines
  • Scope mounts
  • .22LR conversion
  • Accessories overview

If you noticed how often the terms explanation and demonstration are used, you may be getting some idea of why this course is necessary for any CETME, H&K, or G-3 owner, or someone who intends to be.

Weight0.25 lbs
Dimensions7.56 × 5.44 × 0.63 in


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