Thread: Max fluting depth

Hi guys and gals. Going to flute a stuffed 308 barrel for fun. From what I have read, you dont want to flute any closer to the bore than .2" or 5.8mm. This will only give me a maximum depth of 1.57mm in my flutes. NOW... this rifle has a stuffed barrel and will only ever be run with subs. (Will stamp subs only onto barrel). How deep could I safely go considering lower pressures? Possibly to .150" or 3.8mm from bore?
Cheers

5.8mm sounds excessive, most sporter weight barrels wouldnt have that much meat at the muzzle even before threading.

Try it and report back how many rounds it takes to split the barrel

Id suggest you dont dont do it at all but if you do then Please err on the side of caution, find someone with a factory fluted barrel in the same caliber, messure it up and dont go any closer to the bore than they do. Really you should add another 1mm on to be on the safe side.

One thing you have to be wary of is that some barrels out there are far from straight, the bore can move around quite a bit in the barrel and be a mm or more close to one side, if you go ahead and flute a barrel like that you could be a lot closer to the bore than you think.

Originally Posted by veitnamcam

5.8mm sounds excessive, most sporter weight barrels wouldnt have that much meat at the muzzle even before threading.

Just because a barrel is thin at the muzzle does not mean flutes can go that deep. In a round barrel once you fire the barrel tries to expand evenly around the circumference, on a fluted barrel the bottom of the flutes is all that expands so there is a lot more stress on the material.

interesting question . . . i would say go with the industry standard and cut the barrel as short as you can, say 12'' if this is about saving as much weight as you can. . . but if the barrel is stuffed whats the point.

Originally Posted by DPT

Just because a barrel is thin at the muzzle does not mean flutes can go that deep. In a round barrel once you fire the barrel tries to expand evenly around the circumference, on a fluted barrel the bottom of the flutes is all that expands so there is a lot more stress on the material.

Yes of course.

Thanks for the reply's guys. Barrel is already 13ish inches and light as. But this is an experiment! @DPT safety is definitely my main priority for testing. Whilst this will be retired to subs only, I'll do some full power tests with a LONG piece of string tot eh trigger to take away any doubt. I'm thinking 20 rounds should be sufficient. I'm drawing it all up on CAD at the moment and will post pics soon.

Originally Posted by Tuckerbox

Thanks for the reply's guys. Barrel is already 13ish inches and light as. But this is an experiment! @DPT safety is definitely my main priority for testing. Whilst this will be retired to subs only, I'll do some full power tests with a LONG piece of string tot eh trigger to take away any doubt. I'm thinking 20 rounds should be sufficient. I'm drawing it all up on CAD at the moment and will post pics soon.

Can you slomo video as well please?

@marky123 unfortunately no means of slomo footage. Here are some drawings. A little more digging suggests Pac-Nor happily flute to within .150" or 3.8mm of the bore so I did drawings for both 5mm and 3.8 clearance. The square bottomed flutes look a little ridiculous on the 3.8mm clearance barrels. But I'm happy with the looks of the 3.8mm with 4.5mm ball end mill.

How would you support the barrel ?use your iphone 5s 120fps...!

Remember, peak pressure is reached on the first 5 inches of bullet travel then goes down quite quickly . That is a lot of effort for such a short barrel. You will probably get away with two Vee block evenly spaced under your barrel ( providing both ends are supported of course)

The mill I have access to has a chuck and tail stock, much like a lathe. @marky123 thats a nice thought but i don't own an iPhone... Yup its a lot of effort but it's just for fun. Might as well practice now on a crap barrel then wreck a good one.

Originally Posted by 7mmwsm

Could you just call it porting instead of fluting if you go to deep?

Slotting

You are intending to use a ball end mill? If so I'd say the finish will be a bit average

Originally Posted by MSL

You are intending to use a ball end mill? If so I'd say the finish will be a bit average

Grenades don't have to look pretty.