06-13-2023, 03:13 PM
Downloaded this to read later. One thing near the end however caught my eye, as it is a key part of how I've been doing things.
Get a dispersion of shot-loads/MVs to cover your expected MV range, to get the curve (actually a linear curve fit) of MV vs charge load for that particular combo in that gun.
His variation study of shots-grs powder vs MV confirms that linear curve exists.
At that point I narrow myself into looking at the range of a more or less known node-velocity (OBT) for that barrel length. Chris Long theory. I have those nodes in an xls I developed.
That's why I earlier said that I think OP will find something that works in the 2475-2510 range for his howa-20" hb. Once you find an acceptable SD (I try for <10, ES in the teens), the remainder is to find a primer (if you have that option) and an OAL that gives the best groups.
Getting that curve for powder etc combo in YOUR gun is the key starting point.
I know other guys use other means, which is ok AFAIC... this is my way. Seems to work for me.
ps, in general a different bullet (same class), even a different powder (with a similar pressure curve and speed) doesn't affect this approach by very much.
Get a dispersion of shot-loads/MVs to cover your expected MV range, to get the curve (actually a linear curve fit) of MV vs charge load for that particular combo in that gun.
His variation study of shots-grs powder vs MV confirms that linear curve exists.
At that point I narrow myself into looking at the range of a more or less known node-velocity (OBT) for that barrel length. Chris Long theory. I have those nodes in an xls I developed.
That's why I earlier said that I think OP will find something that works in the 2475-2510 range for his howa-20" hb. Once you find an acceptable SD (I try for <10, ES in the teens), the remainder is to find a primer (if you have that option) and an OAL that gives the best groups.
Getting that curve for powder etc combo in YOUR gun is the key starting point.
I know other guys use other means, which is ok AFAIC... this is my way. Seems to work for me.
ps, in general a different bullet (same class), even a different powder (with a similar pressure curve and speed) doesn't affect this approach by very much.
"Down the floor, out the door, Go Brandon Go!!!!!"