6MM Dasher freebore math for Berger VLD bullets

[darkangel_r2]

With all due respect sir, something is not correct with your math. I shoot dashers with 105 VLD'S and you are coming up with way too much freebore. See post #9.

I was accounting for his conditions of only using .122" or 1/2 caliber of bullet in neck for the shorter bearing surface bullet. For seating using the whole neck length for the 105 vld you would subtract .122" from my first number making it about .160" which is much closer to standard. He was asking for a non standard seating setup unless I misread his request.

Edit: figured it out, I combined the freebore and leade lengths. Corrected freebore numbers would be .090" min and .150" max.

 

[707electrician]

I was accounting for his conditions of only using .122" or 1/2 caliber of bullet in neck for the shorter bearing surface bullet. For seating using the whole neck length for the 105 vld you would subtract .122" from my first number making it about .160" which is much closer to standard. He was asking for a non standard seating setup unless I misread his request.

Is it standard to seat the bullet so the bearing surface is in contact with the entire length of the neck? I would think you wouldn't want to seat that deep so as to keep the boat tail out of the case as much as possible.

 

[WIB3]

Dashers love bullets in the 103-107ish range. Tried and true, many have tested different but the records speak . Get a 1-7.5 to 1-8 twist barrel and have a blast. Free bore from .135 to .155 and you are golden. Of course there is no secret combination, you will have to test and do some work. Power, primers seating depth all play roles in the equation also.

 

[darkangel_r2]

Is it standard to seat the bullet so the bearing surface is in contact with the entire length of the neck? I would think you wouldn't want to seat that deep so as to keep the boat tail out of the case as much as possible.

@timeout
I think I know where the screwup is. My freebore calculation includes the leade. So my numbers are freebore+ leade length. Posts corrected above, thanks for pointing out goofy math.

 

[Dave M.]

Agree 100%. I honestly wouldn’t shoot anything heavier than the 109’s from the 1:8 twist dasher.

I just ordered a new barrel for my dasher in 1:7.5 twist so I can try the 3000 109’s I’ve been sitting on for two years. My 8 twist didn’t like the 109 Berger’s.

 

[Old Navy]

I don't think any of the BR series cases are big enough for the 115 VLD.

 

[BoydAllen]

@timeout
I think I know where the screwup is. My freebore calculation includes the leade. That maybe the source of discrepancy of numbers. So my numbers are freebore+ leade length.

What is the typical leade length on a dasher?

I read a lot, and I have never read or heard of anyone calculating a feebore in a manner that you seem to be trying to use. Listen to those that post here. I have a "gizzy cut with the same reamer that my 6BRA barrel was chambered with. with it, a selection of bullets, and a carefully measured case I was able to drop each bullet into the back of the partial chamber, measure down to the back of the bullet, subtract the length of the BT and come up with how much of each bullets shank would be in in the case neck. The reamer print shows the FB at .104. I think that it is just fine. Since the Dasher has a shorter neck, and I want to stay well away from the neck shoulder junction, for one of those, I might opt for .120. Send me one of your bullets and I can do the same with it.

 

[darkangel_r2]

I read a lot, and I have never read or heard of anyone calculating a feebore in a manner that you seem to be trying to use. Listen to those that post here. I have a "gizzy cut with the same reamer that my 6BRA barrel was chambered with. with it, a selection of bullets, and a carefully measured case I was able to drop each bullet into the back of the partial chamber, measure down to the back of the bullet, subtract the length of the BT and come up with how much of each bullets shank would be in in the case neck. The reamer print shows the FB at .104. I think that it is just fine. Since the Dasher has a shorter neck, and I want to stay well away from the neck shoulder junction, for one of those, I might opt for .120. Send me one of your bullets and I can do the same with it.

Yep, typical leade length on a 1.5 degree .236 dasher is .143" which when applied to my earlier numbers gives .090" min to .150" max with .120" splitting the difference. I just forgot that my calculation would include the leade.