Dasher freebore

[Mulligan]

I have a Dasher with a .104 freebore. It shoots 107s and 108s really well.
I have read several times on this forum that many Dasher shooters are using .135 or .155 freebore.
What are the advantages of the longer freebore?
CW

 

[22DASHER]

More room for powder!! And keeps the bearing surface out of the neck shoulder junction

 

[Mulligan]

More room for powder!! And keeps the bearing surface out of the neck shoulder junction

what is considered the optimum freebore?

 

[22DASHER]

what is considered the optimum freebore?

Oooo nooooo..... That question will start a fire storm.

.135"-155" for 108 Bergers or 105 Hybrids.
You can get away with a slightly shorter freebore with the 105 VLDs

 

[DennisH]

Oooo nooooo..... That question will start a fire storm.

.135"-155" for 108 Bergers or 105 Hybrids.
You can get away with a slightly shorter freebore with the 105 VLDs

When replacing a barrel, I always take 3 dummy rounds to the gunsmith and have it throated to match. As someone mentioned above, this keeps the bearing surface in the neck.

Plus, the freebore usually falls somewhere around the above measurements.

PS: I also have a BRX which puts a kink in the above process. You have to have it set perfect as your trying to get as much contact in the neck.

 

[Dusty Stevens]

.125 fits everything. .155 shoots good but wont fit all bullets

 

[dkhunt14]

The longer freebore gives you more case capacity which allows for more powder. Most times this allows you to get more velocity with less pressure. That makes it easier on brass. It also gets the pressure ring of the bullet in front of the donut area. I also like the pressure ring to be in the sized part of the neck. With bushing dies the area near the shoulder isn't sized. I use a .155 with 105 VLD's. I would not go less then .125. Matt

 

[Mulligan]

If I plan to shoot 105-108 gr bullets exclusively is the .155 freebore better then the .125-.135?

 

[dmoran]

Mulligan -
In my own experience, yes.
Donovan

 

[Alex Wheeler]

I have settled on .140" with a 1.560" chamber length. Works perfect for the 103 vapors, 105 vlds, and hybrids. Chamber length matters when comparing free bore numbers. This is on a JGS reamer.

 

[tclaunch]

Here was an entertaining thread from back in 2011 on this very subject....

http://forum.accurateshooter.com/threads/freebore-mug-shots-6brx.3777808/

 

[johara1]

If you shoot into the lands you use a shorter free bore, but if you jump them you need longer free bore. How much you jump them is big factor in free bore length. Free bore diameter is an other issue with fat bullets…… better know what bullets you plan to shoot and how fat they are to start with. Barts 105 a .135 is long for them Vaper trail .135 to .150 is good, EPS. .135 is on the short side and .150 is better Hybrid 105 .150 is good depending on how old the bullets are they changed them since i used them. The short .104 free bore is out of the question anymore but you can make them longer, but not shorter ……. jim

 

[Northridge]

As others have stated it's not a line item dimensionally. In a 1 degree 30 type throat depending on bullet your using I have also seen zero touch very more than .020th on the same throat. I've been tinkering with a bore rider type throat lately and I've seen engagement very 105 hybrid 1.774 105 hunting vld 1.778 then a 105 bart's at 2.830 in Sam e throat demention so a lot of research in bullet to be used will affect grind. I would agree that for me .130ths to .140ths seams to accommodate several bullets I tend to use. 107 Sierra and 105 bart's seam to require fare less throat for same location in neck.

Shawn williams

 

[Mulligan]

What velocities are you getting with the 105-108 gr bullets with the longer (.125-.155) throats?
Yesterday I worked up to 36 gr of H-4350 in my well used dasher barrel (read, lots more freebore then the .104 it started with) with a 107 SMK, no pressure signs yet and could still squeeze a little more powder in there. The load was shot over my chrony recording a velocity of 3152, ES-14, SD-5.4. Is this anywhere near the results others are getting?
Accuracy was a bit better with 35.9 grains, velocity nearly identical.

My standard load of 32.5 gr of Varget measured 3048 FPS yesterday and that is right where it has always been.
I believe my chrony my be suspect, anyone else have similar results?
CW

 

[Jefferson]

Anybody have a dimension for the lapua 105 bullets. Jefferson

 

[DennisH]

Anybody have a dimension for the lapua 105 bullets. Jefferson

I can send you a couple.

Dennis

 

[savagedasher]

I have settled on .140" with a 1.560" chamber length. Works perfect for the 103 vapors, 105 vlds, and hybrids. Chamber length matters when comparing free bore numbers. This is on a JGS reamer.

140 '' is the best number I have found. But no less then 130''. 500 rounds depending on the powder the 140 ends up being 145 or more . Larry