why do they have a flutted chamber

[winky]

just curious as to the resoning behind it. Ive never seen it in anything other then a cetme or H&k.

[MicroPilot]

This allows a small amount of gasses to float the case out aiding in extraction.

[Geilt]

These flutes reduce the cartridge case's bearing surface and permit propellent gases to flow around the case acting as a lubricant to ease extraction. As delayed blowback does not offer the available power reserve of gas operation under adverse conditions and there is no primary extraction, chamber fluting is required for reliable functioning. Ejected cases are all marked with distinctive striations but, contrary to popular belief, this does not affect their potential for reloading.

... copied from another source.

[Rampager]

This is actually the beauty of the design IMHO. A CETME or G3 can extract even with no extractor in place. Doesn't eject well without an extractor of course, but it will extract the case from the chamber. I learned this from a video on the old Cetmerifles site Perro had posted illustrating this.

[yongxingfreesty]

yup, it's one cool rifle. I like it alot.

here is the video of the extraction without extractor.

http://youtube.com/watch?v=uK52PNJ1awM

[okie shooter]

They tried other ways of allowing for extraction other than fluteing, includeing olive oil on the cases, but lubrication is not a good idea in combat situations(japanese hotchkiss guns are an example). The soviet tokarev automatic rifles used flutes too.

[hunter_la5]

Ive never seen it in anything other then a cetme or H&k.

IIRC, the Swiss Stg 57 and the Russian SVT-40 also used fluted chambers

[winky]

must work because ive never seen a gun that throws brass like this thing!

[robocop10mm]

I heard for years that you could not reload them because of the distinctive ribs left on the case. I have been reloading the HK-91 fired cases for 15 years and have not had a single issue with the flutes. The real issue is the body dents and extractor marks caused by the violent extraction/ejection. An ejection port buffer will minimize the dents but occasionally the rim of the case gets worn to the point it must be discarded.

I installed a new extractor on my 91 and the damage to the rim all but went away. Perhaps a worn extractor is the real culprit.

If you are afraid to reload HK/CETME fired cases, send them to me. Heck, I'll even pay the shipping. I'll be happy to give you a complete range report on how they do.

I have never had a FTE with my HK (over 3000 rounds fired). The CETME Ripped the head off a case on the second shot fired through it. Got a broken case remover and has not hiccupped since. I think it was a bad case.

[winky]

I did do some informal reloading testing. If you look farther down on the page you will see my results. I dont believe its the flutes that cause the brass failure in them but the excessively big chambers in them. It takes quite a bit more then normal pressure to resize the brass shot out of mine anyway. I had a case crack in half and the front stay in the gun on the 4th reload of lake city brass. Load wash pushing a 147 ball bullet to about 2500 fps. I now will reload my brass 3 times and pitch it unless further loadings show me that i need to ajust that theroy. I would say that in my opinion if a guy really wanted to get brass life out of this gun it would about pay him to take a few pieces of fired brass in your gun and send them in and have a custom set of dies cut that wouldnt overwork the brass and youd proably double brass life. Fortunatley i have about 2000 rouns of lake city brass and about another 1000 commercial and mixed headstamp military so it should keep me going for a while. Ive heard horor storys about the commercail brass failing so im going to use it just for 2000fps cast bullet loads in it.

[40mmHEDP]

Man, it is refreshing to see some intelligent conversation about reloading for the Cetme/HK rifles. I never usually discuss this subject in a forum because of the the landslide of cut and paste posts by self proclaimed experts that have never loaded a single round.

Brass in good condition is good brass period, military, commercial, whatever. It's not all the same but that does not mean you cant develop a load for it. The best brass in the world will blow up on you if improperly loaded for YOUR rifle in YOUR chamber.

Remember that somebody, somewhere(a mortal man) developed the first load, the first rifle design, the first anything period, used and tested it, made mistakes, had success to get us to this point. The only task we have is to use all these components intelligently.

I will also gladly pay shipping for all the .308 brass people want to get rid of. It's for your own safety after all. Just read the Internet! Just having a reloading press within a 3 meter radius of a CETME will cause it to spontaneously explode. Save yourselves and send me your brass.

[pigpen]

I think most will agree that 3 reloads is about as much as you can expect from CETME/HK fired brass.(depending on how hot you reload) If you can even find the brass in the 1st place.

[jfowl31]

The problem with some commercial brass is that most/some of it is so soft that in order to dumb down the load in order to make the case NOT stick, it will not work the action, and will jam every round or very often.

I honestly don't think reloading is the greatest idea for a Cetme, because some are not responsible with what they do.

With these rifles, I'm thinking the lowest load that will reliably cycle the action is the best one... the recoil is so mild, that you can be grossly overloading, and causing a lot of wear, and never know it because the action is still worked right... the cases arent sticking... but you dont know that because youve got too much pressure in there, you are hurting the rollers, or the LP... whatever.

I will say that I would confidently reload for the Cetme, because I am a responsible reloader, as most are. But I wont recommend it to others because I dont know how responsible they are... same with anything really, but a semi-auto is much more finicky, and can actually cover up mistakes in the reloads sometimes.

[winky]

I respect your oppinion alot as you seem to be one of the more knowlegable cetme gurus here. Only agrument i can make to your post is the fact that if your buying bulk military 308s and shooting them out of your cetme your probably subjecting your gun to as much wear and tear as someone who is handloading and using loads from a respectable loading manual. A handloader that is inexperieced that doesnt load with a reloading manual is a complete idiot and deserves to have his gun destroyed. Ive found that my gun runs just fine using starting loads in the manuals and that puts velocity at 2400- 2500 fps with a 150 and i doubt if factory or miltary bulk is that mild. Bottom line is an idiot is an idiot and the same idiot that finds he needs to hotrod a gun like this is the same idiot that will try light mags or some such crap anyway. To me this gun more then most NEEDS to be handloaded. I can eaily control the pressures my ammo i running at and i sure cant do that if im constantly looking for a cheap allways changing supply of surplus ammo. You never know what your getting with that stuff or what a foriegn country uses for powders or if there the same everytime. About the only way to be consistant is to buy something like black hills or lake city and that stuff is to expensive to blast up beer cans with.
The problem with some commercial brass is that most/some of it is so soft that in order to dumb down the load in order to make the case NOT stick, it will not work the action, and will jam every round or very often.

I honestly don't think reloading is the greatest idea for a Cetme, because some are not responsible with what they do.

With these rifles, I'm thinking the lowest load that will reliably cycle the action is the best one... the recoil is so mild, that you can be grossly overloading, and causing a lot of wear, and never know it because the action is still worked right... the cases arent sticking... but you dont know that because youve got too much pressure in there, you are hurting the rollers, or the LP... whatever.

I will say that I would confidently reload for the Cetme, because I am a responsible reloader, as most are. But I wont recommend it to others because I dont know how responsible they are... same with anything really, but a semi-auto is much more finicky, and can actually cover up mistakes in the reloads sometimes.

[40mmHEDP]

Agree 100% Winky,

"To me this gun more then most NEEDS to be handloaded."

The only way your going to get "perfect" ammo consistanty for any rifle you have let alone the CETME is to make it your self.

Of course there is good ammo out there to buy. But an experenced reloader is much better off, financialy and quality wise, rolling his own in my opinion.

It's like if people suggested that the danger of food posioning is too high therefore you should never reheat leftovers and even making your own food exposes you to risk to high to be acceptable. The only affordable solution is Fast food for every meal....

[rep30cal]

The flutes allow the gas to escape around the brass, as they say "to float
the spent round out of the chamber". As I read one time, and it made sense
to me, with the CETME design using no flutes would be a blowback ejection.
A blowback ejection like on a handgun uses the weight of the slide and on
a rifle it uses the bolt weight to counter the recoil. A blowback bolt for a
.308 would have to weigh approximately 65 pounds.

As for reloading for the CETME, I have had very good luck working up a load
for mine. A person must use common sense when reloading and work the loads up till you get a happy medium between accuracy and pressure, hotter
IS NOT always better. I use only military brass and retest anytime I change
a reloading componant.

[Geilt]

I respect your oppinion alot as you seem to be one of the more knowlegable cetme gurus here. Only agrument i can make to your post is the fact that if your buying bulk military 308s and shooting them out of your cetme your probably subjecting your gun to as much wear and tear as someone who is handloading and using loads from a respectable loading manual. A handloader that is inexperieced that doesnt load with a reloading manual is a complete idiot and deserves to have his gun destroyed. Ive found that my gun runs just fine using starting loads in the manuals and that puts velocity at 2400- 2500 fps with a 150 and i doubt if factory or miltary bulk is that mild. Bottom line is an idiot is an idiot and the same idiot that finds he needs to hotrod a gun like this is the same idiot that will try light mags or some such crap anyway. To me this gun more then most NEEDS to be handloaded. I can eaily control the pressures my ammo i running at and i sure cant do that if im constantly looking for a cheap allways changing supply of surplus ammo. You never know what your getting with that stuff or what a foriegn country uses for powders or if there the same everytime. About the only way to be consistant is to buy something like black hills or lake city and that stuff is to expensive to blast up beer cans with.

The issue with reloading, especially on a rifle with a fluted chamber, is the use of non-military spec brass. The commercial brass like Win and Rem, is thinner walled. Even a moderately reduced load in this kind of case can cause the brass to flow in to the flutes causing an FTE or at the very least the brass is getting a heavy workout.

I do agree with you however that a responsible handloader is more apt to get a suitable and safer round than someone who either tries to run straight up commercial 308Win or reload with the proper components and understand what they are trying to accomplish. More so they need to understand what they need to avoid. Most reloading manuals don't include military loads so its left up to the individual to either piece one together from annecdotal information or try to modify a 308Win load.

[winky]

not using commercial brass was one of the first things i was told on here. I did shoot a box of commercial ww through it the first day i had it as i didnt have any other ammo and didnt know any better it all ran through the gun fine. I have also used commercial brass with good results using cast bullets at about 1900 fps. the recovered brass does not show flute marks but being that it is soft and is worked so much in that large chamber im sure even at those levels its not good for any more shootings then the military brass is with 2500 fps loads.

[Geilt]

I think we're getting way off topic here. If we want to continue the direction this thread is heading, why don't we start a new thread in the Reloading section.

[winky]

guess i dont see where this is offtopic a bit. Nobody is post specific loads and its all related to the original question of how the flutes interact with this gun.

[M1 Tanker]

I'm sure we can tell you the same thing we tell everyone else...if you shoot commericial .308, just keep your broken shell extractor handy. We have seen a lot of ripped casings in the last 5 years. People are just trying to save your a dime and a headache. Not to mention the extreme pain of trying to dig brass out of chamber flutes.

[winky]

ive got first hand experince with that allreay. Had one fail the third day out with the gun. Tied up the gun for a couple weeks until a got an extractor.
I'm sure we can tell you the same thing we tell everyone else...if you shoot commericial .308, just keep your broken shell extractor handy. We have seen a lot of ripped casings in the last 5 years. People are just trying to save your a dime and a headache. Not to mention the extreme pain of trying to dig brass out of chamber flutes.