I just measured the throat in the 6XC barrel on my T2K. It is the original 25†Polygon barrel they supply.
When new, an 85 gr Sie was 3.065†after chambering a long round and letting the Lands soft seat the bullet.
I was using the Sinclair Nut Thingy to check the length.
At 1047 rounds the same was 3.085†so I had .020†erosion.
At 1560: I just measured it @ 3.096â€. So I have a .031†increase based on soft seating. I am using the same bullet in the same case I had set up on the shelf for this very purpose. Seems a bit small to me but I repeated it several times and it was the same.
Note that a lot of the rounds were the 70 gr Sie for 200 yd XTC: @ 35.0 gr Var. The 85 gr Sie for 300: @ 34.0 gr Var- and the 107 @ 600 with 39.0 gr IMR 4350. If I were running all the rounds with the 107’s @ 2900 I believe the throat would be out a good deal more than it is.
YMMV.
Reid
When new, an 85 gr Sie was 3.065†after chambering a long round and letting the Lands soft seat the bullet.
I was using the Sinclair Nut Thingy to check the length.
At 1047 rounds the same was 3.085†so I had .020†erosion.
At 1560: I just measured it @ 3.096â€. So I have a .031†increase based on soft seating. I am using the same bullet in the same case I had set up on the shelf for this very purpose. Seems a bit small to me but I repeated it several times and it was the same.
Note that a lot of the rounds were the 70 gr Sie for 200 yd XTC: @ 35.0 gr Var. The 85 gr Sie for 300: @ 34.0 gr Var- and the 107 @ 600 with 39.0 gr IMR 4350. If I were running all the rounds with the 107’s @ 2900 I believe the throat would be out a good deal more than it is.
YMMV.
Reid