6 Dasher initial setup questions

[jhord]

Hi all-

I'm having a barrel chambered for 6 Dasher in the coming weeks. I'm trying to work out a few things ahead of time. Pierce Engineering will be doing the chambering, he has a reamer suited for 105 class projectiles but is a .269" neck. I just picked up a new blue box of Lapua brass and I did some measuring, the neck thickness is in the .0120-.0125" range on my tubing mic. I haven't loaded any dummy rounds but with my other blue box stuff for my 6BR, this nets a .267-.2675" loaded neck which I shoot in a .272" no turn chamber. So I'm pretty sure I'm going to have to give the necks a light turning for the .269 chamber, .0015" doesn't sound like enough clearance. My questions:

1) what would be a good neck clearance to shoot for? .003"?

2) how far down should I turn the necks? I see the Dasher is listed as having a .246" long neck. Go that far and stop, a little beyond, the whole neck?

3) I think I'll false shoulder it for fire forming. How does that factor into the neck turning, as far as how far down to turn the neck?

I guess what I'm looking for is input from someone experienced with the 6 Dasher, what steps would YOU take to get this brass ready. Thanks in advance.

 

[tclaunch]

I always turn the whole neck on the BR case, false shoulder, then fireform. Too little clearance is much worse than too much and your .003" will work fine. This will net you a .266" loaded round. I turn the whole neck as a BR to not encourage donuts forming. Have fun with that new tube!!

 

[RDavies]

Same here. I use the same neck turner for 6BR and 6 Dasher and turn down to the neck. Then I neck up to 25 cal, form a shoulder and jam the bullets hard into the lands, with 3-4 thou neck tension (for first fire forming) and necks cleaned with shellite (white spirits, lighter fluid) this gives good neck tension. I always go for about .002"- .003" neck clearance with 6mms. Even Lapua brass could do with a slight clean up if you need the extra clearance anyway.

 

[jhord]

That's what I needed to know. Sounds like I should take a quarter thou off the whole neck length, see where I'm at, and then maybe take off another quarter thou if needed. I ordered a .25 cal expander mandrel from K&M this morning to use for false shouldering. Once I get all that stuff figured out and rounds built for fire forming, I'll send off my Forster die for the proper neck honing. Thanks! I'm looking forward to playing with the new Dasher!

 

[potatoe]

I didn't turn the whole neck of the BR case. I only turned .260 down the neck

 

[pmarauder]

+1 on turning down the neck to .260..... No need going all the way down the 6br neck. Just as long as your about .010 to .015 below where the new neck/ shoulder is going to be on the dasher. That will still keep you from forming a donut.