dasher freebore help please

[jasperjet]

Building a 6 dasher for 105-108 bullets only.I need to set a bullet in a 6br case for the smith. Smith has a ptg reamer 0 freebore . Can someone tell how far a 105 vld should be in the neck to get the desired .104 freebore.And about how much shrinkage occurs when fireforming. Thanks

 

[drano38]

jasperjet
I built a Dasher a year ago and had PTG make me a reamer. Dave said for the 105/107 gr bullets we need .104 freebore to keep their base in the neck.

Here's my OAL's:
Berger 105 gr = 2.432 w/ .020' jamb into the lands
SMK 107 gr = 2.360' w/ .015' off the lands
A-Max 105 gr = 2.307 - don't remember jamb/jump but I think they are .010 or .015 off the lands

If you can afford ~$140, I'd suggest getting your own reamer. A friend strongly encouraged me to get my own after he had a 'smith chamber a barrel in 6 BRX. But after examining fired brass, it wasn't a true BRX.
As a minimum, I'd ask the smith for a reamer print, then compare it to PTG's standard Dasher print. Since PTG made it, its very likely a standard Dasher. But some of the dimensions may have been adjusted for whatever reason.
And the lead angle will affect things too. My reamer is 1.5 degrees which Dave recommended for the high BC bullets.

drano

 

[falconpilot]

.104 freebore is what you want..I've done it in 2 guns, and it has worked perfectly with 105/108 bergers, 107 Sierra'.....

May I suggest that you give Dave Kiff a call and order your own reamer...I had a well known gunsmith chamber a gun for me once with his 'reamer', and it turned into a nightmare...If you can afford to build a gun, go ahead and do so with you own, new reamer..it'll save you alot of headaches down the road, plus, when you rebarrel, you can continue to use all your brass...

I went with a Kiff - .104 FB, .269 neck, 1.5 degree lead

 

[wnroscoe]

My Dasher reamer is a PTG and it has .104' free bore, 1.5 Degree Lead and a .272' NT neck. Works like a charm. I shoot the 105 Berger VLD's +.015' in the lands.

 

[jasperjet]

roscoe how much bullet is in the case with a .015 jam

 

[wnroscoe]

The base of the bearing surface is above the neck shoulder juncture point. I ran the same free bore in my .269' nk 6BR just touching the lands, same bullets, same results, no problems.