Need help forming some wildcat cases

J

JRB

Guest
I need to form some 17 mach iv 'improved', cases out of some 222rem brass.
Now i realize you are thinking, why not use the 221 case, well i have but, there is a over sight on my part!
I know i need to give as much detail as possible,

Many years back i bought a second hand mach iv barrel and fitted it for some varmint shooting, well after a short time the bore was gone. I really liked the case and its performance, so i decided to get a reamer from DK, fitted a Lilja barrel and fire formed my old '221' come 'mach iv' cases to the new improved version.

My improved version has minimum case taper and 40 deg shoulder, sort of like a 'AI' version i guess. The problem was that after many years of fire forming AI cases of all sorts of cases, i wanted to achieve consistently formed case. Maintain case uniformity and wall thickness. I have found that when forming a big blow out like a 220 AI and even my little mach iv case, the cases stick first at the mouth, then blow back along the case to the base, stretching and thinning the wall in varying amounts, also the case length will vary hugely by up to .040", depending on how they stick and hold. Once trimmed this will give miss uniformity of the case.
I have found the only reliable way, to form the case, with minimum case length variation is with some hornady butter on the case, to prevent it from sticking at the mouth as it is formed. This gives results of only a few thousanths variation in length. I have also found that when using the 221 case as a donor that the case neck length is greatly reduced as the blow out is large enough to absorb the length.

Now hear is the problem, in achieving a new case i need more length at the finished case, so i have opted to use the longer 222 rem case.
So how do i reduce the case shoulder length?
I have found with using either neck forming dies or FLS die, that the case just crushes or squashes, rather than reduces in size.

I am starting to think that i need a series of larger diameter forming dies that will reduce the case diameter from the shoulder back to my desired shoulder height, in the same way a neck forming die works.
Does any one know how the brass is made from new, and how they achieve the desired shoulder and neck?


The experimental Mach IV imp. has been a huge success and really shoots well, and achieves 4180 fps with the 20 vmax, it is fantastic out to 450 yds on varmints.
I have put off making new brass for some time, so really want to get this done.
I also have the worn barrel re chambered to the improved case, with an extra .100" in the neck length, so i can cut the new cases long and then fire form and trim.

All suggestions appreciated!
Jim
 
I have a set similar to the set in the previous post only made by Shadetree Engineering they are fantastic.
I have used them to form .20 Vartarg, .221 Fireball, and .300 Blackout from .223 Rem. I have also made
6.5 Creedmoor from .308.
I also like making cases from a longer parent case. The cases I form are trimmed to maximum length to
safely chamber and when they fire form the neck is a lot closer to correct length.
I have never lost a case forming this way, just remember to use good lube, I use Imperial Wax.
 
Would it not work to incrementally neck down the 221 fireball brass with a 17 mach iv full length bushing die until you had a crush fit?

I have a set of the case reducing die bushings, and they do work. Then the work begins. Cutting cases, fighting thick necks, possibly reaming the inside of the new cases.

Are you sure you actually "need" the finished cases to be longer?

I read where Lapua is supposed to be offering us .221 Fireball brass in the near future?

Good luck.

Kurt
 
Jim,

You're working too hard! Go get a bag of 17 fireball brass, load it, & shoot it.
The 17 fireball is just a commercialized version of the Mach IV. Works in my 17 Mach IV Bullberry barrel for the contender.

Regards,
Ron
 
I totally agree that forming 17 Fireball, or 17MIV, is a pain, but during the winter, I always do a few.

I start with a deprimed once fired military 5.56, or a 223. Swag the primer pocket.

Ultrasonic clean, lube, and size with a 221 TRIM die.

For my 17FB, I ground down a shellholder, just a little, so I could squeeze it down a little more. This prevents a slight buckle that forms just below the shoulder.
At this point, I trim with a little cut off saw, turn the necks, Then into a 17MIV form die, finish with a 17FB FL die, anneal, chamfer, prime and load.

I'd like to say they are better than factory 17FB, but so far, I can't.

There are many ways to do this, this is just how I do it.

Jim
 
Great suggestions,
Just what i was hoping for, so many thanks.
I have sent an email to the guy on the forum, who makes step down dies, they look really good.
I like the idea of having changeable step down sizes, he says they used to be made by Skip many years back.

Just waiting to hear back.

What is the best way to cut the case to length before trimming to to exact size,

Jim
 
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