Dasher freebore

[Gilbert Garza]

How can I tell freebore of my barrel ?
I have a Dasher barrel that with a 105 Berger Hybrid sits at 1.7110 with .015” off the lands. So based on my measurements I’m at 1.726” BTO with a 3-24 comparator. This is my first Dasher but it’s a shooter, just curious on freebore length. Not sure if their is another way of measuring.

Thank you in advance

 

[retired]

ask the guy that chambered it or the reamer maker ?

 

[Gilbert Garza]

We can’t find the reamer print. And the reamer only shows “dasher .272” that’s legible on the reamer itself so can’t ask the manufacturer.

It’s more of a curiosity thing, still getting really good speeds out of a 26” Bartlein barrel & Varget. But I wanted to know, wondered if there was a way to measure based on other people’s measurements.

 

[Sheldon N]

You're about 0.050 to 0.060 shorter than my .104 freebore Dasher barrels.

 

[Gilbert Garza]

So that would theoretically put me at .040-.050” freebore

With only running 105 hybrids & JLKs would there be any issue except maybe the loss in case volume ?

Currently I’m running 32.9g of Varget @ 2980fps in 26” 1-7.5 Bartlein

 

[wmcclendon]

Hmmm...sounds like my freebore. I'm super worried it's not going to work for these longer bullets.
What brass are you running?

 

[dmoran]

My experience for the 105 type bullets, short FB will pressure out sooner, and bullet seating can be subjected to neck/shoulder junction issues. As to accuracy?... can only speak from myself, which is: was not able to get the accuracy from shorter FB's like I did from +.135". My current 6Dasher reamer is a .160" FB.
Donovan

 

[Gilbert Garza]

Hmmm...sounds like my freebore. I'm super worried it's not going to work for these longer bullets.
What brass are you running?

Lapua brass
So far I’ve tried 105 Hybrids and just today JLK’s and had tried some 115dtacs about a month ago. Accuracy is stupid, speed is good For me. Currently running 32.9g Varget @ 2983fps in my 26” barrel. It hasn’t been hot here, mid 80’s most days so don’t know what it’ll do in 100* heat. I was more worried overall length for the sole reason that I’m running this in my AX rifle and was thinking it might feed more reliably if it was longer. But so far it’s been a great caliber. Only shot a tad over 400rds but it’s become probably my favorite caliber. I’m actually selling off all my 6 creedmoor stuff to fund more components.

 

[Gilbert Garza]

My current 6Dasher reamer is a .160" FB.
Donovan

I know throat erosion is not as bad on the Dasher but with it sticking out so long do you feel that you’ll have enough in the throat and bullet to be able to chase the lands being .160fb ?

Mine currently is at 1.725” BTO with hybrids, if i continue to chase I’m assuming I’ll have a full 2000rds before the throat is gone. Again assuming about .025” of erosion every 1000rds.

Thoughts ?

 

[expiper]

Gilbert....tell us how much bullt shank you have in the case neck when touching the lands and then we can give a very good estimate of FB length,,,Roger

 

[dmoran]

@Gilbert Garza
Have had 6Dasher's with .175" and .205" FB's as well. Did run out of case with the .205" to early, but the .175" was not a problem to +2000-rounds. The longest I ever went was 2600-ish before I set it back.
Donovan

 

[Gilbert Garza]

Gilbert....tell us how much bullt shank you have in the case neck when touching the lands and then we can give a very good estimate of FB length,,,Roger

Pardon the dumb question but how do I measure this ?

I’m guessing measure the bullet and measure the overall length minus the case ?

 

[expiper]

Pardon the dumb question but how do I measure this ?

I’m guessing measure the bullet and measure the overall length minus the case ?

Dont complicate it,,,,set a bullet on the case mouth and measure it ,,,,that is the long measurement,,,,then seat the bullet to the correct length ,,,then measure the diff,,,,that is how far you pushed the bullet in the case neck,,,Roger

 

[Gilbert Garza]

@dmoran this being the first Dasher we did here in the shop I guess I’m new so used what i had. It works, i ain’t complaining at all. I’ll have a better idea on pressure in the summer. I ran a water test and didn’t have issues with primers or sticky bolt so I’m ok for now.

And a longer bullet just looks sexy af

After the Lone Star match I may use the new throater we received and open it up at tad.

 

[Gilbert Garza]

@expiper if i did this correctly I’m at .514” of bullet into the case.

 

[expiper]

@expiper if i did this correctly I’m at .514” of bullet into the case.

ooo my ,,,,the neck is only .215 +/- ,,,I have never seen a FB that short,,,your bullet is wayyy down in the case and robbing you of case volume,,,,my chamber with .150 FB a 105 Hybrid is ~.160" of shank,,,I dont even see how you could have that much shank in the case ,,,,did you measure the ctg length with the bullet clear out and then seated properly,,,,(the boat tail section should not come into play)....Roger

 

[Gilbert Garza]

Sorry that is with boat tail length also
I got creative with math since I was at work and couldn’t seat a bullet. But I had a fired case and bullets so I started measuring.
I know my OAL length is 2.31” touching the lands, hybrids are 1.278” so I subtracted case length of 1.547” and got .514

But it should be 2.33” in lands, 1.278” bullet and 1.547” case length. Leaves .495” but that’s also the boat tail.

 

[Gilbert Garza]

@expiper i did it again

I placed a bullet on a sized case, BTO on that was 2.0060”
My bullet seated to the lands is 1.725”

Leaves me with .281”

 

[expiper]

@expiper i did it again

I placed a bullet on a sized case, BTO on that was 2.0060”
My bullet seated to the lands is 1.725”

Leaves me with .281”

thats more like it,,,,,just guessing ,,,,your FB is ~.040".....you can shoot 107 SMK (I think,,),,,I woudl use a shorter 90 gr Berger till the bbl/throat get some wear on it,,,they only woul;d be seated at ~.170" shank,,,that even leaves room to jump ~.020" if you need to,,,,Roger

 

[Gilbert Garza]

What do yours measure at shank?

I have a throater, I may open it up after next weeks match, that’s when I should be getting my JLKs and need to do load workup again.