Help with determining free bore

[jsthntn247]

I was wondering if yall could give me an idea of what the free bore on my 308 Tr rifle is. I used a Palma reamer and had it throated out to my specs. Wondering if I didn't ask the smith to do it out to far because my base to ogive is running 2.336 with the Juggernauts at a Jam. There is not very much bearing surface left in the case and I'm trying to figure out if it's better suited for a 200 or 215.

 

[Erik Cortina]

The number does not matter, if you need more of the bullet in the case, get a longer bullet.

 

[expiper]

how much bearing surface is in the case,,,????....~.100 is plenty,,,Roger

 

[jsthntn247]

The number does not matter, if you need more of the bullet in the case, get a longer bullet.

That was the point of the question

 

[jsthntn247]

Expiper seems to be around .140 in the case the best I can tell. I want to try 1000 yard match this summer and am trying to determine if I have enough freebore for the 215's. Everything I read on the heavies talks about freebore length and I don't know what mine is since it was throated and not on the reamer.

 

[Erik Cortina]

You said you had the chamber throated to your specs. What were your specs?

If the case will hold the bullet straight and with consistent neck tension, you are good to go.

 

[expiper]

If you have .140 of that bullet in the case when jammed ,,,your FB is ~.190"...that shuld be good for the 210-215 bullets,,,,,you have ~.270" of useable neck before you aproach the donut,,,and if your ND is above .340 you shuld have no problems ,,esp if using a bushing style sizer (they only size ~.185" of the neck so the rest stays out of the way,,,,a nice long FB gives the bullet a cylindrical bore (with .0002" of clearance)that guides the bullet into the lands if you decide to jump .030-.050",,,I hope this answers your questions and eases your mind,,,Iv'e been doing these calcs. and shooting for 50 yrs now Roger

 

[jsthntn247]

If you have .140 of that bullet in the case when jammed ,,,your FB is ~.190"...that shuld be good for the 210-215 bullets,,,,,you have ~.270" of useable neck before you aproach the donut,,,and if your ND is above .340 you shuld have no problems ,,esp if using a bushing style sizer (they only size ~.185" of the neck so the rest stays out of the way,,,,a nice long FB gives the bullet a cylindrical bore (with .0002" of clearance)that guides the bullet into the lands if you decide to jump .030-.050",,,I hope this answers your questions and eases your mind,,,Iv'e been doing these calcs. and shooting for 50 yrs now Roger

Yes that helped allot. I started with a 95 Palma Reamer and added .100 to the freebore. So I figured I was at .155 to 160 to start. My throat has moved some over 750 rounds so 170-190 should be just about where it's at. The gun is hammering the 185's still, but it shoots best at 2630. If I could get the 215's to 2550 I would have a 15" wind advantage at 1000. Not sure if 2550 will be accurately doable however.