Chasing the lands or chasing fairies

[hunter686]

I'm about to confirm my drawings for the reamer of my new 6.5 and have a question regarding freeborn and throat erosion.

The original freebore is 0.055 designed to fit the AICS DBM of 2.880. I have changed the freebore too 0.140 which means an 140 ELD-M will hit the lands at around 2.934 keeping the bearing surface above the N/S juntion. A modified AICS (front plate removed) mag will allow a Coal of 2.950. A loaded round touching the lands leaves 0.016 max mag length.

I understand its unlikely I'd go with a round touching the lands but worst case scenario is 0.016 a bit too close? I also have the option of the alpha mags which allow a COAL of 2.965 (0.032 over the lands)

The question is: is this 0.032 enough space to allow seating for throat erosion in a mid to hot 6.5? Or should i consider bringing the freebore back a few thou?

Rifle will be a low volume LR steel and crow gun i.e barrel won't be getting the 3rd degree too much

It's worth adding I have the facilities to set back my barrel at anytime.

Thanks

 

[Terry]

Keeping the bullet out of the donut area is a primary goal. Beyond that less freebore equals longer barrel life.

 

[Alex Wheeler]

I want at least .050" clearance in a mag. You will get into issues running it tight. Hornandy bullets dont seem to have a pressure ring, you will be fine seating them into the doughnut area if you dont size the whole neck, and you have enough neck clearance.

 

[hunter686]

Keeping the bullet out of the donut area is a primary goal. Beyond that less freebore equals longer barrel life.

Intersting! What's the correlation between seating long and barrel life?

I want at least .050" clearance in a mag. You will get into issues running it tight. Hornandy bullets dont seem to have a pressure ring, you will be fine seating them into the doughnut area if you dont size the whole neck, and you have enough neck clearance.

So you think maby move the COAL back in that case?

 

[Terry]

Intersting! What's the correlation between seating long and barrel life?



So you think maby move the COAL back in that case?

The longer the freebore, the less in the case. Sooner or later you run out of case or barrel ware reduces accuracy.