Help forming 6mm AI from 7x57

[Webster]

Try a 10W30 or 10W40 motor oil lube on one case. It may not help but there is nothing to loose. Let me know if it helps. If the increase in oil film thickness reduces the force required it may help???

 

[Elwood]

I can certainly confirm that RWS brass is tough. I had 17 firings from my batch and it was still usable, and I wasn't mothering it either, this was in a F class rifle and pushing Dtacs at 3250fps.

The Winchester brass wasn't bad either, 9 firings without a single loose primer pocket.

 

[kombayotch]

You should be able to form 40 degree shoulders directly, without having to resort to things like COW fireforming. I do 35 degree shoulders directly. Making them 40 degree shoulders would be one more step. The trick is to bump the shoulder back with progressively smaller necked dies that have a 20 degree shoulder. Using progressively smaller dies will help prevent puckering at the neck-shoulder junction.


7mm Kraken case forming

I also shoot 6mm Crusader, which is basically the same as 6mmAI, but with a 32 degree shoulder.

Here is my method:

1) Anneal the case down to where the new shoulder will be.
2) Lube the case up and run it into a 308 Win die. Adjust the die to put the body-shoulder junction where it needs to be in the new case.
3) Repeat 2) with progressively smaller dies that have a 20 degree shoulders (7mm-08, 260, 243, for example). Trim dies work well, or buy cheap used sizing dies and chop them down if necessary...
4) Anneal the case again once you get to the desired neck size.
5) Run it into the final sizing die with the final shoulder angle. (I would use a die with a 30 degree shoulder at this step for your AI, maybe even a 35 degree shoulder die, then do another step with your AI die).

You end up with something that looks like a factory case. Shoulder is even a bit sharper.

A lot of steps? Yes... but I still find it a lot faster than blowing out the cases with COW. Especially since I can do it at any time (read 1am when the missus is sleeping) in my reloading room. Goes pretty fast on an XL650...

 

[Changeling]

You don't, good catch, use 6mm bullets and 6mm Rem type brass.
You can of course use any brand of brass you want. I used Winchester brand because a friend had some problems reforming Remington brand brass.

Do NOT oil the cases you are trying to fire form!

 

[Webster]

Sounds like a lot of work to make a barrel burner. A 6BRX would be simple to form cases. Almost as fast as a 243AI with a lot less powder?

 

[GT Accuracy]

i got the 7x57 brass sorted out! all good but thanks for that head up

 

[ShootDots]

Sounds like a lot of work to make a barrel burner. A 6BRX would be simple to form cases. Almost as fast as a 243AI with a lot less powder?

There is no way on this Terra Firma that ANY 6BRX or Dasher can possibly equal the velocities you can obtain with a 6MM Rem A.I. You are burning 16-17grs less powder. That translates to 50pct MORE powder in the A.I. I used to get 3400+ F.P.S. with a 105A-Max (for Deer hunting) with "about" (can't remember exactly) 50grs of RL-22, AND that was with a 26" barrel.. For hunting, the 2 are nearly as different as night and day.. However, you are correct in that the 6mm Rem A.I. is a barrel burner. On the other hand, I doubt there are many people using it in F-Open competition.

 

[Elwood]

, I doubt there are many people using it in F-Open competition.

Except me
Possibly one of the most accurate rifles I have ever had, which beat many Big 7's including WSM's. In the end I only moved away from it because of the barrel life and a .284 made more sense as I could use it in short range competition and practice. Another added bonus for F class was the minimal recoil.

Without doubt a awesome caliber with a huge grin factor, but as with everything good there's a price to pay.

 

[ShootDots]

Elwood, that's why I said "not many">> I knew there had to be some people out there who wanted extreme performance! There is no doubt of the cartridges "ability" >> just as you stated. It is the loss of barrel life that would keep shooters from using it more. That (The 6mm Rem AI) and the 6-284 would be incredible>> but barrel life is prohibitive..

 

[Webster]

Clue me in. What do you hunt with a 243AI? I have been hunting GH for 45 years. Now using a 6BR. I seldom shoot beyond 350 yrds. With a laser range finder and a good drop chart for your bullet and MV it seems that FPS isn't the issue it was 20 years ago. I can place a bullet within 1" of where I want it at 350 yrds. People seem to always talk about flat shooting but they ignore the wind drift (22 calibers) Not trying to be pessimistic. I understand the faster you shoot a 80-90 gr varmint bullet the less wind drift you will have. I can afford any rifle I want but I don't want to buy a new barrell every 2 years and get on a 6 month waiting list. Also I don't want more than one rifle. Does the 243AI typically shoot small groups? My rifle shoots under .350" groups all the time. Good hunting fellow hunters no matter what you shoot.

 

[expiper]

I agree with "Webbbie"....it is not a matter of $$$,,,but a matter of down time and inconvenience waiting on gunsmithing and shipping and ordering bbls....that wastes the most prescious thing we have "our time"...time better spent enjoying days of shooting and the good life..Roger

 

[jde650]

How would you size a 7x57 case in a 6.5x284 die according to berger loading manual the shoulder on a 7x57 is 0.4299 a .284 is 0.4748 there is no support for the 7x57 case wall. I bet they collapsed.

Jim