JGS 1045 Reamer

[Jud96]

The leade angle is what helps center the bullet to the bore. It’s a cone with a slight angle that’s typically 1.5 degrees. Even if you’re seating bullets into the lands, that leade will help center that bullet. However with a tight freebore (.2433-.2435) if the bullets measure .2433-.2435 (not uncommon) then essentially you’re swaging the bullet with the freebore and not letting the leade center the bullet as well.

 

[DaveTooley]

Here's a number most haven't done the math on. An increase of .0001" per side in the FB, with 1'30" lead, adds .0038" to the length of the FB.

 

[DJSBRS]

The leade angle is what helps center the bullet to the bore. It’s a cone with a slight angle that’s typically 1.5 degrees. Even if you’re seating bullets into the lands, that leade will help center that bullet. However with a tight freebore (.2433-.2435) if the bullets measure .2433-.2435 (not uncommon) then essentially you’re swaging the bullet with the freebore and not letting the leade center the bullet as well.

At what point after throat erosion begins, does the leade or lands become non concentric? Does this then becomes a mute point for concentricity?

DJ

 

[DaveTooley]

At what point after throat erosion begins, does the leade or lands become non concentric? Does this then becomes a mute point for concentricity?

DJ

What discipline?
I know BR guys who set there barrels back occasionally to get a fresh leade. I don't think they do it because of concentricity issues, but having fresh lands allows them to use their bag of tools keeping the rifle in tune.

 

[Shooter13]

I think the .060 free bore is a bit much for BT bullets,.045 I think is optimal, but my thoughts and $2 will get you a cup of coffee but not at Starbucks! LOL

 

[jackieschmidt]

Years ago I also started with a .262 1045 JGS.
When I went to a .269 neck, I shortened the Freebore to .050. Everything else stayed the same.
You can ask Dave Kiff at PTG who was the first shooter he ground a ..269 for.

 

[Tim Singleton]

So .4402 @ 200 line would be fine if using a custom die or add little extra?

IME .4415 works well .442 wouldn’t hurt at the 200 line

 

[ShtrRdy]

Years ago I also started with a .262 1045 JGS.
When I went to a .269 neck, I shortened the Freebore to .050. Everything else stayed the same.
You can ask Dave Kiff at PTG who was the first shooter he ground a ..269 for.

What case length were you using with the 0.050" freebore?

 

[jackieschmidt]

What discipline?
I know BR guys who set there barrels back occasionally to get a fresh leade. I don't think they do it because of concentricity issues, but having fresh lands allows them to use their bag of tools keeping the rifle in tune.

^^^^^^^^^
Exactly.

 

[turkeynut]

Do you all think this would work with 68grbt Barts or any other bt?

 

[ShtrRdy]

Do you all think this would work with 68grbt Barts or any other bt?

I would take an educated guess and say yes.

 

[Tim Singleton]

Do you all think this would work with 68grbt Barts or any other bt?

If you would increase the .200 line to 4415
I would say it would be about perfect!

 

[jackieschmidt]

What case length were you using with the 0.050" freebore?

A Lapua 220 Russian fireformed to 6PPC will end up about 1.490 to 1.495.

 

[J.J. Coe]

A Lapua 220 Russian fireformed to 6PPC will end up about 1.490 to 1.495.

Did you keep the chamber length 1.525?

 

[Mulligan]

The Micron die is built (as far as I know) for that reamer. It works perfectly for me regardless of how hard I push it. Freebore length, diameter, and neck diameter are the areas I would look at while keeping in mind changes in either the neck diameter or freebore diameter may change the effective freebore.

I’ll post a pick of my print in a few minutes as a visual.

CW

 

[turkeynut]

Going from .2433 to .2437 fb diameter, how much would that change fb length? I would like to some of your prints. Thanks

 

[xr650rRider]

Going from .2433 to .2437 fb diameter, how much would that change fb length? I would like to some of your prints. Thanks

0.0076" increase and within their tolerances, could be a .2442" and would increase by .0172".
Intense overthinking things.