I look forward to that article too JB.
Currently working with a 7x57, economy A&B 21" bbl ( I was gifted several vz-24 recievers, A&B bbls in various chamberings, reamers, go/nogo gages, Timney triggers, sporter stocks, & so forth). Dyna coated the bore due to the A&B bore is very prone to copper foul.
Anyhow, worked w/ Hornady 139 IL & Nosler 150 BT. Goal is to get some background w/ Nosler BT, then work with 150 Nosler Accubonds for the final load.
Seated the Hornady to 3" oal, per Hornady book. I did the slit case neck, start bullet, push case in chamber until case shoulder butts chamber shoulder. OAL =3.080". Hornady 139IL jump is ~0.080". 2700 fps per crono, makes 1 3/4" @ 100.
Nosler 150 BT seated to 3.070" (SAMII max is 3.065" per Nosler book). I did the slit case neck, start bullet, push case in chamber until case shoulder butts chamber shoulder. OAL =3.150".
I conclude that the Nosler 150 BT is jumping ~0.080". This shoots ~1.00-1.25" @ 100 yard. W/49gr IMR 4350 makes 2815 fps per crono.
Intuition tells me to jump the Nosler BT a bit less, say 0.050" using same powder weight. Given I'm working with an A&B barrel, could be that 1" 3-5 shot groups could be all I can expect.
I've always approached seating depth (bullet jump) as trial & error. I'll say it again, looking forward to that article JB.
Pat
Last edited by TooDogs; 10/24/17. Reason: friggin typo
