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8mm kurtz

4K views 29 replies 9 participants last post by  1biggun 
#1 ·
thinking of another conversion for the future while i work on my current project. how hard or easy would it be converting to 8mm kurtz? maybe just open up the bolt face, see about mags and maybe turn and rechamber a mauser barrel? I'm not looking to start a 7.62x39 vs 7.92x33 debate I just am in love with 8mm rounds. also if there is other posting about this conversion (i couldn't find much) then let me know, i'm not trying to beat a dead horse
 
#2 ·
7.62x39mm very closely duplicates the ballistics of 8mm kurtz, except the wider shorter bullet of 8mm does have a lower B.C. The shorter overall length does allow you to load longer heavier bullets, and yes the 8mm Kurtz rounds do seem to work OK in an AK magazine- i was able to load the 15 I have into an ak mag, seemed plausible. Would be a good candidate for a subsonic or silenced AK, or as a hog hunter.
 
#5 ·
yes exactly guys i like throwing around ideas i like an ak system so far (working on my first) but i have also thought about the possibilities of making a faux stg44 from a cetme. I like 8mm for a heavy shorter bullet like you said hog gun, or maybe pistol type bullets also it seems it would be easy to make brass for an 8mm kurtz, not to mention PP new produced ammo and possibly finding DDR surplus. are there any members here (especially from colorado or western nebraska) that turn barrels? (I know some guys who would do it but for future needs i would prefer doing business with community members)

for 8mm kurtz mags i could always get more of those awesome french 7.5 mags and shorten them very easily. but i'm thinking i would want a curved mag as the kurtz has a very soft tapper to the case and would probably like a curved mag for easier functioning. so probably the standard ak with 15 rounds like you said, was that in an ak 30rnd mag?

what would be very cool would be making a mag well like the g3 mag guys, an underfolder stock, or extend the receiver past the rear trunnion use the rear trunnion just for the recoil spring and cover fitment and then either another like homemade trunnion or just a welded in plate in the back to have a shorter wood stock shaped more like a stg44, just to give a stg44 feel to the whole thing like a what-if type rifle like what if they used the stg44 as more of a foundation for the ak...... just ideas i suppose, I like projects i guess haha,



or here's another idea real quick, neck down a kurtz case to 5.56..... shorter but fatter thatn 5.56 nato
 
#6 ·
If it is going to be a CETME you might want to start with an HK-33 bolt carrier. You could cut down the weight of a CETME bolt carrier. I have Soviet post war drawings of 7.92x33 and I have the CIP specs for the cartridge. I think the Soviet book I have is dated around 1946 and has technical drawings for WWII cartridges. I was hoping it would have early 7.62x41 / 7.62x39 drawings but it doesn't. It does have 30 Carbine, 30-06, 8x57, etc. With an AK you wouldn't need chamber flutes and a Mauser or FN-49 barrel could be used.
 
#7 ·
Hello moleman,
Thanks for the link !!!

The fluting machine appears to be a single flute electrode EDM that pulls the electrode toward the chamber rear. The power supply is not pictured nor is the dielectric fluid supply. Typically the power supplies are a pulsed DC, RC network (resistance - capacitance).

The fluted chamber for gun barrels has been around since late WW-I, "The Great War". They replaced oil injection or wax coating ammo in several MG's where rather violent extraction happens.

I experienced the same stonewall when enquiring about chamber fluting (via engineering friends) at H&K and Rhinemetal in Germany. A BFD secret !!!

VD
 
#9 ·
Hello moleman,
Thanks for the link !!!

The fluting machine appears to be a single flute electrode EDM that pulls the electrode toward the chamber rear. The power supply is not pictured nor is the dielectric fluid supply. Typically the power supplies are a pulsed DC, RC network (resistance - capacitance).

The fluted chamber for gun barrels has been around since late WW-I, "The Great War". They replaced oil injection or wax coating ammo in several MG's where rather violent extraction happens.

I experienced the same stonewall when enquiring about chamber fluting (via engineering friends) at H&K and Rhinemetal in Germany. A BFD secret !!!

VD
Somewhere out there in al gores intra net there's some pictures of a guy using a less fancy setup with some good closeups of his broaching tool. I couldn't remember where I saw it a couple years ago and the extra years haven't helped me remember where I saw it about 2005/6. Luckily Gwailo was able to find something from my ramblings. That might explain why the metal strip looking thing going into the chamber looks so thin if it is an edm setup. I have no idea how a edm works, but it would seem that that the barrel or electrode would have to be insulated from the frame in order to work? It doesn't look like it is in the pictures though.
 
#8 ·
very cool guys i asked a question about fluting an ak chamber in the ak biy section for ak use (if it would smooth things out and allow using much lighter recoil spring and less gas for the gas system) as far as the 8mm kurtz it seems like i would be able to cut down 8x57 cases or heck even 30-06 cases form them in a die then do a final trimming since the base, from what i have found, is .472 or so like the cases i mentioned.
 
#12 ·
Hello moleman,
That fluting machine seems to be an EDM since as you mentioned the little rod in the barrel chamber appears to be an electrode rather than a broaching device.

That electrode likely is mounted via insulation to the machine and a hot wire connects there to the elctrode. The ground wire would connect to the barrel.

As an engineering student I designed and built a small EDM machine a few decades ago. The EDM had an idiot simple "feedback circuit" that let the operator know when the electrode got welded accidentally to the work. That does happen even with the big buck machines. My heavy duty resistors were 200 watt lightbulbs. When the electrode welded and "grounded out" the bulbs (2 of them) would light up !! That signals it's time to back up and break contact. Fun stuff !!!

VD
 
#13 ·
Good catch Viper Dude! I remember the original thread I saw was a home made broach and just figured back then that this one was the updated version since it had been a couple years since I saw the thread. I thought the broach looked too thin at the time and thought maybe it was just a mock up. I wasn't even thinking about an edm. I saw some home made edm plans on ebay a while back. Looks like the guy is still selling them 2 years later... EDM Machine Sinker Plans Build CD Broken Tap Extractor - eBay (item 160394607217 end time Feb-11-10 17:43:52 PST) Just figured it fell into the snake oil salesman catagory. Thanks for the information, I'd love to have 1/4 of the machining knowledge you have.
 
#16 ·
yep there are a suprising number of sources for new commerical 7.92x33mm kurtz. also easily formed from 8mm mauser or similar cases. Still there is no point in doing this for the FMJ round, its near identical to the 7.62x39mm russian; load up subsonics or 8mm soft points at least.

I was able to load 15 rounds into an 30 round AK mag- there was room for more but I only own 15 rounds of DDR 7.92x33mm. i imagine it would fit 26-27, but not sure the curvature will let that many rounds feed without binding.
 
#17 ·
Hello moleman,
The EDM you referenced looks strangely like mine from 30 years ago !!! Wow, time flies when you are building neet stuff !!! I started with an ancient EDM circuit from a 1950's Pop Sci mag and up-graded it from a half wave rectifier to a full wave (bridge diode type) to get about double the power output. It was a challenge as I am not an EE.

The referenced manual machine uses however a Craftsman MIG welder as the power source. Cute idea !!!

Hello nkluksda,
The EDM you referenced is a more involved machine that uses an automatic feed system with a feedback circuit like the big boys use. The EDM industry in the US once the largest in the world has vanished and moved to Europe (Germany and Switzerland). One of my college profs was a world-class authority on these "non-traditional manufacturing processes". I was always asking him EDM questions.

Even back then I realised that the EDM had small arms manufacturing potential as well as aerospace applications. However the process is VERY slow as it is a spark etching thing but it will carve even hard or exotic metals. A properly shaped tool-electrode can carve a wierd-shaped blind pocket (locking recess on a Soviet DP-28 for eg.). Those DP locking lug pockets were originally done with a special Metal Shaper machine shaping to a horizontal relief cut.

The EDM machine can do some very cool things in a small home shop that not even a CNC mill or lathe can do. Besides "etching" chamber flutes you could even etch small portraits in reverse on the side of your AK's from a tool made from a coin. Yes, an Abe Lincoln Commemorative AK from a penny !!! haha.

VD
 
#18 ·
i just checked for fun and midway has an 8mm kurtz hornady die set for 69$ not bad for an uncommon round and as far as the chamber reamer i have no clue but i wonder if a 8mm mauser barrel could have part of the chamber section cut off and even if the shoulder of the 8 kurtz is not as shart couldn't you use valve lapping paste on a kurz case and i guess lap the chamber till it fits right?
 
#20 ·
hmmmm if the ammo is not a deal Im not sure what you are gaining over other rounds that are more common but hey its all part of the fun.


My book shows making brass out of 308 win. a 32x308 barnes type round would be very simular. there is a 8mmx308 wild cat as well. there are lots of cheap 8mm barrels out there to play with.
 
#21 ·
The RCBS die set is number#56343..7.92mmx33Kurz Mauser. it is their category 'G' set of dies.

1. I mark the approx. length on the 308 case with a fine tip magic marker.
2. Cut to length with a small pipe cutter.
3. Lube and run through the 7.92x33 Kurz sizing die. This will put the bottle neck on the case.
4. Using a drill press vice, ream on drill press with 8mm reamer. I tried holding the cases with a vice grips, but it just don't work. Finally bought a drill press vice and it works slick. I could not find a 8mm reamer locally so ordered one from: Machine Shop Discount Supply
5. Trim to proper length.
6. Case is now ready for loading, i.e. primer, powder, bullet.
Hornady 8mm 125 grain spire point bullet. 21 grains (20.0-22.0gr)(or 19.5-23.0gr depends on source) IMR 4198 powder and large rifle primer.

Lots of info.

Reloading MP44 Directions 7.92x33 8x33
 
#26 ·
Well after a pot of coffee, two of my sleepy brain cells were working well enough that I think I found the original thread I was thing about for broaching the chamber flutes. HK Weapon Systems Forums: Chamber fluting jig complete (pics) I can't tell for sure since the thread was from 2004 and the pictures are gone. It does explains how he used a spring loaded file as a broaching tool to cut each chamber flute one at a time. That plus the earlier thread I linked to earlier for a jig design would get you in business fluting chambers. I wonder if you could custom grind a long 1/8" carbide tipped masonry bit for a cutter?
 
#27 ·
looking at the balasitics of the kurtz i dont see how it would any better as a hog gun than a 7.62x39 in fact it might be worse. I just dont see any real advantages in building one over a x39 that cost less than half to shoot.

other than the fact your the only one on the block to have one it relly dont offer much extra in any given area. possably a better round if made subsonic but not by much. velocity is not any better in fact looks worse. the energy is not a big differance. Id have to have a few cases of ammo to want to build one personaly. I dont think its a bad round just that there are equal rounds more avalaible and cheaper.
 
#28 ·
Hornady made one run of loaded ammo for Graf a couple of years ago. The Hornady bullet that is right length and weight has been discontinued. There are a few retailers that still have the bullets in stock. Prvi had an explosion at their plant. There is loaded Prvi ammo that was imported. If nobody imports the Prvi bullets the supply of bullets for reloading looks like it will dry up.
 
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