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Discussion Starter · #1 · (Edited)
Cetme / HK Build and Misc Info


Some excellent Info on stripping a kit for a build up can be found at [] this Info refers to the HK, but the process is the same for Cetme.

Receiver info

Cetme Rec

Cetme Semi

Cetme Semi

Cetme Stock to FMP Rec

Cetme Trunion Welds

Cetme FMP Stock Swap


Century Rec- Cetme Mag

Century Rec. FMP Mag

FMP rec.Cetme Mag

HK-Cetme Sights

Mag Catch

Paddle Wheel

Tube comparison

Cetme on Top/ HK on Bottom

Some Good Reading etc.

Field Strip Trigger []
Trigger clean[]

Cetme Trig Pack


Carrier Semi Mod and Trigger Frame mod. The semi spring alteration is for the HK all other info is for both HK and Cetme.

Notice! I have included my own dimentions on the two drawings below. These dim. were taken from 3 new G3 and 2 New Cetme complete Trigger frames and Grip frames. The dimentions I note are within .002" on each group, so the G3 and the cetme are the same. You may still check your own dimentions for it is better to have a tight setup than a loose one!

Trigger Frame Semi Alteration! I doubt that you will find this info sheet anywhere! FAC sold these "Dan Coonan" update kits years ago and many have inquired but I have not seen anyone offer this info. I am a Info slob, so with a little searching I found my update sheet to be added to my above trigger frame info. Have fun!

Notice! That the "Tab Line" dim. of 1.400" in the drawing is not correct to the actual dimention from the top of the frame to the top of the Tabs [which happen to hold your Trigger Frame]. That .020" was too loose of a fit for me!

Instructions in two parts

Lower Mods

Cetme Frame

Cetme Trigger Assembly

Cetme Trigger Assembly

Here is some more stuff

-House of the 51-
military rifle gunsmith specializing in HK - Pahrump Nevada


Q- I am assembling my HK from the ground up and can't figure out how to assemble the cocking handle to the gun. How does this assemble?

A- Look at the cocking handle and you will notice that one side has a hollow section where the spring will sit into. Sit the handle on the table in front of you with this hollow side up and then put the spring into the cutout section. Inspect the cocking handle support (the piece that slides in the cocking tube) and you will notice there is a slot for the cocking handle and a slot for the spring cut into its side. Slide the cocking handle support into the receiver to the point where this slot is visible through the large opening in the cocking tube where the cocking handle is able to be rotated up and into the locked position. Pick up the cocking handle with your finger over the spring so as to be able to hold it tight in the handle. The protruding end of the spring is laid into the end of the slot that is furthest from the muzzle of the gun. As you push the handle down and into the cocking handle support, the cocking handle support will slide back a little in the receiver. This is the trickey part of the assembly and you will notice the cocking handle support will want to spin around in the cocking tube under spring tension. I usually rotate the cocking handle and spring group counter clockwise to the receiver a little when I initially place the spring down and then when the sping is in the correct spot, rotate my hand clockwise and down in the same motion while the cocking handle support is moving backwards. When the cocking handle is in far enough, you will be able to slide the whole assembly forward slightly and this will make the assembly line up to the hole in the receiver where you slide in the cocking handle retaining pin. If you wobble the assembly around a little at this point, the retaining pin will work its way almost completely in place. Then, use a punch to set it into the final position. If the retainer pin is not punched far enough or if it is punched in too far, the assembly will not slide in the cocking tube. The cocking handle assembly should slide without tension back and forth in the cocking tube. If it binds heavily, this is probably a sign the spring slipped during assembly and is no longer in it's correct position.

-House of the 51-
military rifle gunsmith specializing in HK - Pahrump Nevada


Q- What are common operating failures of the HK roller delayed blowback weapons and some possible remedies?

A- I will list below common failures and possible solutions. The list of course does not cover every possible operating error, only the most common.

(bolt moves forward without feeding cartridge)

1) Check that magazine is being held tight by magazine catch. If loose, replace magazine catch spring.
2) Check for deformed magazine lip. Replace magazine if defective.
3) On non HK produced G3 clones, check to verify the front of the magazine mates to the small trunion extension protruding from the rear face of the trunion in the magazine well. If it does not, gunsmithing work will be required.

(bolt does not fully close - cartridge is not fully seated)

1) Check for broken or weak recoil guide rod spring. Replace if defective.
2) Check for carbon or gunk residue buildup in cocking tube and trunion recesses. Clean if required.
3) Check barrel chamber for remnants of previously fired ammunition casings or debris build up in chamber flutes. Remove if found.

(cartridge does not ignite)

1) Check for broken, misshapen or frozen in place firing pin or defective firing pin spring. Replace if defective.
2) Check firing pin protrusion to determine if the firing pin is too short due to manufacturing defect or wear. Replace if defective.
3) Check for faulty ammunition.

(cartridge case will not extract)

1) Check for broken or frozen in place extractor or broken or deformed extractor spring. Replace either if found defective or either shows excessive wear.
2) Check for dirty chamber and or receiver. Pay special attention to chamber flutes. Clean chamber and receiver if found dirty and lubricate receiver and bolt carrier assembly.
3) Check bolt gap. If gap is insufficient the action may not cycle.

(cartridge case will not eject)

1) Check for broken, bent or missing ejector. Replace if found defective or missing.

-House of the 51-
military rifle gunsmith specializing in HK - Pahrump Nevada


Q- I am having a hard time loading my HK91 / 93. When I try to lever it open and then pull the cocking handle to the rear it is REALLY hard to open the action. What's the problem?

A- It is important to understand what function the cocking handle performs. When you initially lever the handle back, there will be a very short distance with no resistance and then it will be very hard to continue. At that point, the levering surface of the cocking handle is levering against the front face of the cocking tube and the front face of the bolt carrier and prying the bolt head apart from the bolt carrier. You can get an appreciation for the force required to pull the bolt head apart from the bolt carrier by taking the carrier assembly out of the gun and pushing the bolt head to the bolt carrier, locking it shut. Then, using your hands, try to pull the bolt head away from the bolt carrier. You will be unsuccessful. This resistance is caused by the locking lever mounted on the bolt carrier which levers against the bolt head. When you lever the cocking handle backwards, the bolt and carrier are being forced apart. When the bolt head and carrier are seperated far enough, the rollers will be able to receed into the bolt head and the action will be fully unlocked.
It is normal to have a substantial effort required to lever the handle to the 90 degree rotation that should be required to open the action. Once the handle is rotated 90 degrees, the action should be fully unlocked and the force required to pull the bolt carrier to the rear and lock into place should be very little. If it is still very hard to pull the bolt carrier to the rear after the handle has been rotated 90 degrees, the action has not been fully unlocked. This is most likely the result of an excessive gap existing between the bolt carrier and the cocking handle support (the part that slides in the cocking tube) when the bolt carrier is fully in battery. This gap existing is sometimes found in non HK licencee produced clones and never found in factory german guns. The fix for this problem is to pull the cocking handle support out of the gun, build up it's rear surface with weld and then turn it down on a lathe so when it sits in the gun, the gap between the bolt carrier and the cocking handle support is almost non perceptable. There needs to be a gap between the two when the bolt carrier is in battery or every time the bolt carrier goes into battery it will be pounding on the cocking tube levering surface. Also, if there is no gap, the bolt carrier is probably not being allowed to go fully into battery and the bolt gap is probably being affected by the interference. On the other hand, if the gap is too big, the action will probably not be fully open when the cocking handle levers to the 90 degree position and it will be very difficult or impossible to open the action. When I have time, I will measure the gap on a factory HK91 and figure out some sort of wire type go / no go gauge gap for the cocking handle support and the bolt carrier. I will post up results here. Such measurements are not to be found in any HK manual I have ever seen.


Copied from

The following is the written response I received from the B.A.T.F. regarding various methods of converting a G3 trigger pack to semi auto only. The main question I had was if it would be legal to weld over or weld a piece of round stock into the existing auto sear pin hole (with the auto parts removed of course) which would eliminate the possibility of installing the automatic fire control parts.

Department of the Treasury

Bureau of Alcohol, Tobacco, and Firearms

Washington, DC 20226

Sept 28, 2001

Mr. xxxx

xx, AR 72653

Dear Mr. xxxx

This is in reply to your letter in which you have requested proper procedure for modifying a Heckler and Koch G-3 machinegun trigger, into a semiautomatic trigger.

To properly convert a G-3 machinegun trigger into a semiautomatic only trigger there are several modifications needed. The modifications are listed as follows:

1. Remove the automatic sear.

2. Grind off the automatic sear notch from the face of the hammer

3. Cut away the front corner of the trigger housing where the automatic sear is mounted, .410-inch from the bottom and .540 inch from the front towards the rear.

4. A new hole has to be drilled to accommodate the trigger spring. The hole dimension is .200 inch drill that hole .165 inch from the front of the new corner and .250 from the bottom of the new corner. These dimensions are for the center of the hole.

5. The trigger spring should be replaced with a semiautomatic trigger spring but the G-3 trigger spring will work.

6. The trigger over travel stop has to be moved towards the rear tang of the trigger .150-inch


7. It will also be necessary to modify the trigger housing. Modify the housing by cutting off the tabs for the front assembly pin. Then adjust the fit of the housing into the receiver.

Title 26, United States code, Chapter 53, section 5845 (b), defines the term machinegun as any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot without manual reloading with a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts from which a machinegun can be assembled if such parts are in possession or under control of a person.

If you do not properly modify the G-3 machinegun trigger pack and install it in your semi automatic rifle, and that weapon fires more than one shot automatically with a single function of the trigger, you would be in possession of an unregistered machinegun.

We trust that the foregoing has been responsive to your inquiry. If we can be of any further assistance, please contact us.

Sincerely yours,
Curtis Bartlett
Chief Firearms Technology Branch

This letter was about building Fals and was copied from the FalFiles Board, but it still applies to any Imported Semi Auto Firearm.

Paddle Mag Release

HK Vs Cetme

Bolt Carriers

Bolt specs


Bolt heads

Cetme/g3 Carriers

Cetme AR15 Rear Sight

Cetme /G3 Wood Stock Comparison

Cetme Bolt Assembly

Cocking Handles

HK Rear Sight Drum

HK Rear Drum Sight - This sight and it's base can be welded to a Cetme, after removing the cetme rear sight base.
HK Rear Sight adjustment []

Eject- Century

Cetme Triple Post Cutaway

Cetme/G3 Triple post

eject- FMP



FAC Receiver Botton

Fac Rec Front

Fac Rec. left

Fac Rec left aft

Fac Rec. Rear

Fac Stamp

Fac tube

Firing pins


G3 Bolt assembly

G3 End cap

More HK VS Cetme

G3 Frame

G3 Front Sight

G3 Trunion Weld

Hammer Springs

Hammers/ Sears

Hesse Receiver Bottom

Hesse Left Rear

HK/Cetme Sights

Locking Piece

Locking Piece spec



Sear Catch



Tube Comparison
Cetme on top G3 on Bottom

HK and or Cetme Port Buffer

My MSG90 Port Buffer [If I ever finish the build]

Side rails for my MSG90

Posted - 03/10/2007 : 09:52:41 AM Show Profile Reply with Quote
Side Rails for your Cetme? This is usually used on HK- MSG90/PSG1 rifles, but who knows? Occasionally JLD [] has 20" Heavy Cetme Barrels for Sale. These Rails can be purchased from [] Ralph makes a really fine product.
All you need to do is a final adjustment so the rails fit snug and all the way into your receiver sides and then Tig weld, Paint, and shoot!


Barrel Press [can't remember who's] or you can use a 12 Ton press for around $100.00 -$150.00

Harbor Freight $99.00


More Info I found. Along with some good Cetme Gun Porn. More to come!

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