Chamber fluting

[Swamp Donkey]

I know some H&K have fluted chambers, something to do with the blowback action or something, but, does anyone know of any 338's that are fluted ?

The reason I ask, is I've been resizing some once fired brass, and a couple were bloody tight, like they were from a different (slack) chamber, and once I finally coaxed them out the dies, they were left with polished 'high spots' all the way around, consistent spacing, and length.

I cannay see any other logical reason for the markings.

Thoughts please......

[StanDeasy]

Reamer chatter during chambering?

[bigfathairybiker]

Looks like the marks were the result of the brass deforming when entering the dies.

I have seen the same thing with brass tube forced through steel holes. Because the tube is larger than can be reformed by the hole, the tube deforms into a ridged shape leaving marked edges.

Mark

Overheard in gun shop someone talking about muzzle loading rifle - "youre need some semolina to pack it out"!!!!!

[M99]

I would be inclined to say same dirt or foreign body inside the body of your die?

Mike

[DaveT]

If they were normal before they went into the die then it must be the die at fault?

If the marks you now see were originally raised ridges after firing from the previous chamber then surely it would have been noticeable?

Never heard of fluted chambers and certainly not in any 338 that I have ever fired.

[Chapuis]

What rifle was the brass originally fired in?
Are the marks on the cases equidistant and the full circumference of the case?

[Blu]

Bdiac, Had this happen to me with a Forster 6.5 Grendel die. I reckon some crud had gotten in there so I took the die apart and cleaned it then lightly polished the inside of the die. That didn't make any difference so I sent Forster an email explaining what was happening to the brass and what I did to try and fix the problem. The email they sent me back said they didn't think crud would do that much damage to the die but they also didn't say what would. End result was they sent me a new die.

Most of the major die makers have a lifetime guarantee thing going, dropping the maker a line with that photo attached may have them send you a new die. I don't think it has anything to do with your rifle.

Blu

[Tiff]

I'd forget the 'chamber fluting' theory, since I've never heard of a .338 with one. However a couple of guesses are:
The new dies have still got some dried oil on the inside and need a really good polish out.
or
The once fired brass is from the AI factory, where they use it for proofing in house - hence the slack/oversized dimensions. I had 600 of these cases and about 10-20% took a LOT of effort to resize with my co-ax. Also their primer pockets are already starting to loosen up and only last 2-3 good loads. Hence my interest in the ppu, hoping it may prove more economical if annealed well...

[Laurie]

Never heard of fluted chambers and certainly not in any 338 that I have ever fired.

http://www.google.co.uk/search?q=h%26k+ ... 66&bih=653

http://en.wikipedia.org/wiki/Blowback_( ... er_delayed

http://en.wikipedia.org/wiki/Heckler_%26_Koch_G3

Via a circuitous design route (Third Reich to Spain to postwar West Germany), we get a partial roller-locking delayed-blowback rifle action that works with full-power rifle cartridges. The problem with the system turned out to be that you couldn't build enough delay in before the bolt started to recoil back attempting to extract a fired case from a chamber that still contained a level of pressure -result, a tendency for the extractor to pull through the case-rim leaving a fired case in the chamber and causing a jam.

Answer: machine in longitudinal flutes around the chamber which allowed a small amount of combustion gas to be interposed twixt case-body and chamber and which 'floated' the case in the chamber, result reliable and easy extraction. This system was used in the Bundeswehr's G3 7.62mm assault rifle and the large numbers of variants sold to around 40 countries as well as HK41 and HK91 civilian versions. It was later used in Heckler & Koch's HK33 series of 5.56x45mm miltary and civilian rifles. Although the German weapons are best known, the system was developed in Spain by CETME and various postwar Spanish military weapons use it including the in-service CETME Ameli, a 5.56mm GPMG that looks like a scaled-down MG42.

Those of us old enough to frequent the ranges pre 1987 and the Hungerford shootings that saw centrefire semi-auto rifles banned often found spent 7.62 or 5.56mm cases lying on the grass and which when left in the wet for a few days showed the fluting marks up clearly. And, in truth, they looked very much like those in the OP's photograph.

I've never heard of a 338 LM rifle that uses the CETME / H&K system, and it seems a bit unlikely for this size and power of cartridge. If it were used, it'd have to be in a semi-auto as there is no benefit from a fluted chamber in a bolt-action rifle.

[ColinR]

Depending on where these once fired cases have come from it might just be indicative that a manufacturer is developing a 338LM semi auto - AI maybe?

I have bought AI once fired cases in the past and as far as I know they mostly use Ruag for testing, but the head stamp on these is not Ruag as far as can be seen. All the cases I have had from AI have a 'T' headstamp (Ruag).

The marking is too regular to be a fault, dirt, whatever in a die. It more suggests a high powered cartridge taking a 'set' in a fluted chamber with the raised area being polished in the die as it is reformed. You will often find 7.62 x 51 cases on military ranges with the exact same marks, but caused by oxidised powder residue.

EDIT: I just enlarged the photo and although not clear they could be either Ruag or Lapua, but I think the latter.