maybe a 8mm mauser cetme????

[turbothis]

so i am looking at my parts kit and wonder if a 8mm conversion is possible. i think the barrel pressure is the real make or break of it though. anyone got specs that will say if it is do-able with the roller delay?

barrel would be easy to lathe one down and press in trunnion,
mg13 mags will do,
bolt head is perfect,
cocking handle should go back enough for the longer cartridge

has anyone had the same dreams as i do???????????

[Darkwatch]

So what are you gonna do when all the old surplus is gone...I don't think anyone is making 8mm mauser ammo anymore...'cept maybe Norma and we know how expensive that is! I know it's a great round but 7.62X51 is a great round too...if you wanted a more powerfull CETME maybe 7.62X54!?!? You could call it the CETMENOV

[turbothis]

hahaa, thats awsome idea!
i am just thinking ease of conversion. the russian round has a larger casing rim so it would involve more work.

[okie shooter]

The length might eat your lunch on either conversion, its always easier to do a shorter cartriage but it drove us ordnance engineers to copy mg-42 design, due to the fact .30-06 is longer by six mm vs 8mm, The same would be true here on either 8mm and 7.62x54r, plus other problems.

If you really wanted to change and have a good chance of working, you could convert to 223 or 7.62x39 though there are 223 guns out there. The 7.62x39 might just require cutting back and rechambering a barrel, pressing the barrel for bolt gap, then its spring tensions, roller combonations to make it work, plus a mag adaptor or block.

[Perro]

most cartridge conversions will not work in a cetme

the cetmes bolt system is DELAYED blowback - whats that mean??
It has just enough "friction" (for lack of a better term) to keep the bolt closed until the firearm bleeds off the energy to a safe level so it can recoil safely
too much "friction" and the gun wont cycle correctly
too little "friction" and the gun will send the bolt carrier backwards at a dangerous level

your problem?? The cetme was designed with just enough "friction" to work with 308

anything underpowered from 308 and it wont have enough umph to unlock the action
anything more powerful from .308 and it will send that bolt flying backwards way too fast towards your face and damage your rifle

the way HK accomplishes 9mm, .45 acp, 10mm, and .223 conversions is they are proficient enough to correctly limit the amount of "friction"
this is accomplished by first removing mass from the bolt carrier (the energy is fighting the mass of the bolt carrier too)
then modifying the recoil spring strength
then adjusting the locking piece until it cycles correctly


this is an operating system best left unmessed with in my opinion - some people have a hard enough time getting them to shoot the caliber they were designed to shoot, much less messing with other cals.


my opinions only

[turbothis]

ya i hear you. i think it would rock to have the ONLY 8mm cetme! you got one perro? lol just kidding..............

[Perro]

spain made a 8mm cetme prototype called the modelo A
they also made there very own sturmgewehr in 8mm kurtz

i have parts from a modelo a in the funky cal if that counts, but no i dont have an 8mm cetme

good luck on your project though

[turbothis]

well i think parts count , so you got me. thanks

[rpmfly2]

Get a FN49 in 8mm and be done! They are great to shoot and last. They were the most expensive to produce because of the manufacturing process and over engineered! I have 5 in various calibers and they appreciate in value!
Don't BUBBA a Cetme!:party0045:

[Karl E. Hungus]

most cartridge conversions will not work in a cetme

the cetmes bolt system is DELAYED blowback - whats that mean??
It has just enough "friction" (for lack of a better term) to keep the bolt closed until the firearm bleeds off the energy to a safe level so it can recoil safely
too much "friction" and the gun wont cycle correctly
too little "friction" and the gun will send the bolt carrier backwards at a dangerous level

your problem?? The cetme was designed with just enough "friction" to work with 308

anything underpowered from 308 and it wont have enough umph to unlock the action
anything more powerful from .308 and it will send that bolt flying backwards way too fast towards your face and damage your rifle

the way HK accomplishes 9mm, .45 acp, 10mm, and .223 conversions is they are proficient enough to correctly limit the amount of "friction"
this is accomplished by first removing mass from the bolt carrier (the energy is fighting the mass of the bolt carrier too)
then modifying the recoil spring strength
then adjusting the locking piece until it cycles correctly


this is an operating system best left unmessed with in my opinion - some people have a hard enough time getting them to shoot the caliber they were designed to shoot, much less messing with other cals.


my opinions only



ahhh BUT!!

could one not then adjust the "friction" by modifying the bold gap? assuming ofcourse the chamber could handle the extra power?

-- on the side, i really wish i could get an 8mm fn49. but the only ones around in my area are in 30.06 and the gun shops want over 1000 bucks for them. i think that might be a tad overpriced, correct me if im wrong.

[turbothis]

i would'nt think it to be bubby cause there is no permenant damage.
mauser barrel
scratch built receiver
no cetme parts harmed during the making of it.

[arnaiz]

most cartridge conversions will not work in a cetme

the cetmes bolt system is DELAYED blowback - whats that mean??
It has just enough "friction" (for lack of a better term) to keep the bolt closed until the firearm bleeds off the energy to a safe level so it can recoil safely
too much "friction" and the gun wont cycle correctly
too little "friction" and the gun will send the bolt carrier backwards at a dangerous level

your problem?? The cetme was designed with just enough "friction" to work with 308

anything underpowered from 308 and it wont have enough umph to unlock the action
anything more powerful from .308 and it will send that bolt flying backwards way too fast towards your face and damage your rifle

the way HK accomplishes 9mm, .45 acp, 10mm, and .223 conversions is they are proficient enough to correctly limit the amount of "friction"
this is accomplished by first removing mass from the bolt carrier (the energy is fighting the mass of the bolt carrier too)
then modifying the recoil spring strength
then adjusting the locking piece until it cycles correctly


this is an operating system best left unmessed with in my opinion - some people have a hard enough time getting them to shoot the caliber they were designed to shoot, much less messing with other cals.


my opinions only
It could be done ....
But as Perro says no by a private shooter, you will need a factory back with preassure canons and lot of Locking pieces to try, and also possibilities to design any one more.
Private owner only can convert the rifle and expect to be rigfht with the development, that means that gun or shooter is in DANGEROUS.
Easy for a factory, DANGEROUS work for a private gun owner.

[WildBillCody]

You have to flute the chamber also, there was a guy once who was trying to make a G3 in 22-250, cool Idea, ut he didn't flute the chamber and he was having problems with extraction.

You would also have to lengthen the mag well for the longer case. If I was going to all that trouble, I think I would rather have one in 7.62x39.

[turbothis]

oh ya. i forgot about the flutes. why are they that critical? most other semi's dont have them.

[okie shooter]

Turbothis, if you look at the history of the CETME rifle devlopement, they had issues on ejection thus they tried to ease the ejection of the cartrage by even using olive oil(there are other automatic firearms that used oil to include I believe the many of the Japanese light machine guns of the WWII era used some form of grease or oil) but oil is not a good idea for cartrages due to the fact they attract dirt, thus fluteing was introduced to help reduce the friction on ejection of the slightly swelled cartrage body by passing some gas to help float the cartrage.

[hunter_la5]

flutes generally aren't as big of a deal in gas operated weapons, but in blowback guns like the CETME and G3, the cartidges tend to stick to the sides of the chamber due to all the gas pressure pushing back on the cartridge. Like Okie said, the flutes allow some of the gas to bleed past the cartridge and create a thin layer of gas that separates the casing from the chamber wall, and allows it to "float" out of the chamber during extraction.

if you dont use a fluted chamber on a weapon system like this, you are going to experience FTE and probably case-head separations as well

[Perro]

as ive said a million times
the cetme is not the platform to experiment on
the bolt system is far too complicated
and the thin stamped sheet metal receiver would be dangerous to you if you got it wrong.
the barrel flutes are needed to extract the case from the chamber. The extractor on the bolt head is only there to hold the cartridge in place until the ejector lever hits the base of the brass. Watch the video on how the cetme will still extract brass without an extractor present in the bolt head. Those flutes keep the brass from sticking to the chamber.
The gun will not work correctly without them. The korean barrels offered by FAC for the g3 had flutes in them, but they werent cut correctly, and many had extraction issues, so even with flutes in the barrel, it wont necessarily extract right.

this is not the system to go modifying - pick a FAL, ak47, AR15, or ANY other gas gun, and you have it easy - blowback guns will cause you to lose your hair at a rapid rate

just shortening the barrel on a cetme, or g3 GREATLY affects the way it operates requiring a change of the locking piece.
just installing a silencer/suppresor to a cetme/g3 greatly affects the way it operates requiring a change of the locking piece
installing a collapsible stock changes the way the gun operates

this gun is delicately balanced by some very smart engineers
trying to change it will either drive you mad and broke, or it can kill you

try your modifications on a gas gun
not a browning 1919 (blow back), not a cetme/hk (delayed blow back), or anything like that. blowback guns require alot of delicate balances

gas guns however are much easier - you simply drill a larger hole in the barrel to allow more gas to cycle the thing and drill bits come in many many sizes to allow you to do this easy, or you reduce the size of the hole in the barrel to make it cycle less hard - easy!
start with a small hole in the barrel and slowly work your way up in size until it cycles correctly, and you will have a much easier time with life.

my opinions only

[jfowl31]

ditto what Perro said... don't even mess with it...


butttttt......... If you were to mess with it despite what has been said, Id think youd be better off with something like 30-06 which duplicates almost exactly the pressure levels of 7.62 nato, and youd just need to cut the chamber.

or something like 243 or 22-250 so that the pressure levels are similar. You start shooting that heavy bullet through it all, and I bet that pressures will get to a dangerous level in a delayed blowback.

If you were doing a homemade receiver and could make a longer magwell, 30-06 seems to be the best bet for a caliber change... but I dont get why someone would change from new technology designed to duplicate old technology in a shorter case.

[Big Steve]

This made me think of something my dad used to say. " If you have enough time, patence and vasoline. An elephant can screw a flea. But is it worth it?"
Steve

[Perro]

rechambering a cetme barrel to ANYTHING wont help you without extending the flutes too

those flutes cover the entire case

cutting it to 06 depth (which is longer than 308) will remove your flutes at the front part of the brass case so now how does the gas get around the brass to keep it from sticking?

also, you wouldnt be able to fit 06 into a 308 magazine, so you couldnt feed your cetme with mags

and the 06 has a much different pressure curve than 308

browning 1919s were originally in 30 06
the israelis converted them to .308
the 1919 works off of blowback from the barrel. It has a muzzle booster that catches gas from the bullet and blows the heavy barrel back until the bolt can unlock and it then blows the bolt back. (much exactly like the way the mg42 works)

if you try to shoot 308 in a 1919 with a 30 06 muzzle booster on it, it wont work well, if at all. SOME guns run VERY lightly with an 06 booster on them, but most dont.

The israelis bushed the 06 booster down ALOT to get it to function correctly with 308

so - pressure spike/curve is MUCH different between 308 and 30 06
i can prove it by letting you shoot my 1919 (which is also a blowback firearm that uses a muzzle booster to blow the operating system back)

using a 308 booster with 30 06 ammo will destroy your sideplates in short order


BUT - make it work, and ill eat crow pie humbly :D

[turbothis]

so it would be the front of the casing that sticks? i imagine a tool could be used to make the flutes. might take a while though, huh.

hey here is a moch up. enjoy

[turbothis]

ya know? i have a 30.06 barrel from a jap 99. it is in good shape and about the right size. it seems to be aftermarket too. i dont think it is a jap barrel anyways.

30.06 fits fine in my mg13 mags so maybe it would fit together better in the end.

i have some old parts that i sit and think about is where all these thoughts come from.