Dasher free bore (throat) on .236 bore

[Dubya]

Have built several Dashers with .104 throat for the 105 Berger on .237 bore barrels. Now thinking of trying
a .236 bore barrel and with a tighter bore I am think there should be more free bore to get the seating depth correct. Anyone know how much more throat will be needed?

Thanks,
Gary


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[yat3b35]

I have 2 Dashers with .236 bore , and use .104 freebore , and it works just fine with 108 gr Bergers , 105 vlds should work as well.

 

[Dubya]

Thanks jh,
Could you share some info? I have some Berger 108 bullets and if you would let me know what your
column overall length is (base of brass to tip of bullet) I could make up a dummy round for reference.

Thanks,
Gary

 

[falconpilot]

IMO...I've had numberous Dasher barrel cut and chambered..the .104 free ore is ok, but shooting 105/108's really seats the bullet deep in the case...I've gone to .124/.125 freebore and like the bullet position much better..I can also shoot a high load to get a little more velocity at the same pressure...or vise versa, shoot same load at less pressure...

Get the .124 freebore...especially with the 105 hybrids..

 

[40X Guy]

As Falcon pilot just relayed, both my Dashers have .125 freebore and both barrels are .236 bore. (same reamer) The bullet ends up being in the right position in the case and also in relation to the lands. It seems to be either .104 freebore or the .124-.125 freebore for 105 class bullets. I have seen .136 freebores also.


Frank

 

[rcw3]

Talking about only the free bore with a wildcat cartridge like the Dasher that does not have a set "max case" length is an exercise in futility - - it's like debating half the equation while ignoring the other half that's essential to the total picture. The third piece is the throat angle which also is not mentioned above (since minor changes in throat angle can also change where the bullets make contact with the lands and sits in the case).

Dasher "max case" length on various reamers runs typically from 1.555" to 1.571", and your free bore sits on top of that, so a Dasher with a 1.571" max case and a .104" free bore is the same (bullet position wise) as a Dasher with a 1.555" max case and a .120" free bore.

If you're going to debate free bore numbers down to the thousandths it seems to me you cannot do so without giving the total picture (i.e. "max case" of your reamer, throat angle and free bore length).

 

[yat3b35]

Thanks jh,
Could you share some info? I have some Berger 108 bullets and if you would let me know what your
column overall length is (base of brass to tip of bullet) I could make up a dummy round for reference.

Thanks,
Gary

As rcw3 stated it does depend on your reamer,my rifles are both chambered with the same reamer and .104 works just fine for them. I don't normally measure from tip of bullet to base of case , but for you I did and that measurement is 2.330" which puts the start of the boat tail right at the neck shoulder junction, and that gives me a .005" jump. My best group at 500 yards with the Bat 3 lug was 1.220" vel. 3050 fps . A .236" bore will create a bit more pressure than a .237" bore.

 

[Dubya]

Thanks very much to all, I appreciate it.
Gary.