6 Dasher False Shoulder Question

[MikeCTX]

Will be building a new 6 Dasher soon, and have been reading the various articles on how to fire form 6BR brass into 6 Dasher and have a question on the false shoulder method. How do you know how far down to run the 6mm die after running a 257/264 mandrel through the neck? I understand that you are using the shoulder to headspace on so is it size, check the chamber until you get a dummy case to chamber tight? Since I do not have the barrel chambered yet just trying to understand how most set up the dies.

Thanks,

 

[ShootDots]

I use the shim from a .38Spcl / .357 die set and had it ground to 97K.. That puts it right up against the neck wall with a bit of resistance closing the bolt.. The Dasher moves the shoulder forward right at 100K, so if you use a 97 / 98K shim, you will make up the difference for the thickness of the brass..

 

[Jet]

Mike

I expand the entire neck to .257 the neck size back to .264 (for my .266 nk) incrementally screwing the die down in stages. I set the lock ring once I can completely close the bolt with a little resistance.

I then fire with pistol powder packed with tissue and NO bullet. Once done I run a 6mm mandrel back through then turn the necks.

After that I load 30gr of Varget and shoot to punch the shoulders out to the chamber specs and to break in the barrel.

Good Shooting

Jet

 

[johara1]

Jet, Why would you do all of that ? Neck turn and stop the neck turner what will be the shoulder and fire form it with a bullet.Blow length should be around 1.550-1.553. I would bet anything that yours are short, doing it that way…….. jim

 

[dogdude]

I'VE tried the false shoulder method many times, they all come up SHORT!! What Jim posted is THE way to go. Best of Luck to you. dogdude

 

[ridgeway]

 

[Jet]

Jim

You are correct, my length is 1.540+ or -. One of these days I'll try the method you describe. Doing it this way I haven't experienced any doughnuts yet (time will tell).

I picked this method based on various posts on this site.

Jet

 

[Charles]

How exact does the turn to distance have to be, and are you measuring it off a dasher case.

 

[40X Guy]

How exact does the turn to distance have to be, and are you measuring it off a dasher case.

I went by the cartridge print and turn the necks on virgin 6 BR cases right at .250 for the false shoulder. Load them with a stout 6BR load and jam the bullets .010 in. My blow lengths are 1.550.

Frank

 

[Phil]

How much do you have to turn off for this to work?????

Say blue box brass at .012, would you be turning to .011 / .010 / .009????

I realize the chamber dictates neck thickness, but if specing a reamer what would work best....

Phil.

 

[Judd]

What's the advantage of a case that is 1.55 versus 1.54? I'm just curious because mine never turn out to 1.55 but I've never done the neck turning method for creating a false shoulder. I typically expand and then only size a portion of the neck.

 

[johara1]

Take the firing pin and ejector out of the bolt is best but at least the firing pin assembly. I run min. clearance on fire forming but the depth is done with a slight resistance on the bolt handless it closes on an empty case you are turning. I have one old K&M that is set and dedicated to fire forming with the chamber i use it in. Long seat the bullets a good .020 and with .004 neck tension …..MAKE SURE THE CHAMBER AND CASES ARE CLEANED OFF WITH NON CHLORINATED BRAKE CLEANER. I would load one round at a time till the desired length is obtained. I use 115 bullets and around 30gr. of Varget. and can vary the length with the load, i shoot for 1.550- 1.553 and use a soft primer like a Federal …….. jim

 

[johara1]

What's the advantage of a case that is 1.55 versus 1.54? I'm just curious because mine never turn out to 1.55 but I've never done the neck turning method for creating a false shoulder. I typically expand and then only size a portion of the neck.

I use a shorter chamber, 1.560 and with a shorter neck more room for carbon and less sealing and less neck to hold a bullet. I can trim to equal length. I neck turn the second time after fire forming and you need equal length to do this. I look for sub .1 groups, equal blow length is a prime factor in accuracy……….. jim

 

[MikeCTX]

Great information guys...Thanks and keep it coming. Always more to learn.