OK, I shot a ladder test @ 400 yds. and had two very distinct nodes. The other 9 rounds were all dispersed in between my two nodes.
I am going to work up both nodes, but I am leaning towards the faster node, as this is for a hunting rifle, and looking at the energy differences, I can get another 125 yds. or so to remain above 1000# of kinetic energy.
The cartridge: .250 Ackley Improved 40°
Case capacity: case capacity for .250 Savage AI is 51.92 gr of water. (Case capacity for .257 Roberts is 52.43 gr of water for reference)
I used the .257 Bob as a loose guide for the new load workup. I have some great loads for a 100 SMK and 100 TSX already, but wanted to work up a 115 Berger VLD load.
The 115 Berger VLDs are seated very long (@ 2.754" COAL and boat tail base is right at the shoulder/neck junction) and were jammed about .010" into the lands for the ladder testing, meaning once I start seating depth adjustments, pressures should go down a bit (being aware I will be encroaching on case space though).
Powder is IMR4350
CCI BR-2 Primers
Starting load was 39.0 (about middle of the .257 Bob loads per the Berger book w. starting at 37.5gr. and under starting loads per Hodgdon manual of 41.9gr.)
Worked up in .5 grain increments
Ending loads with no signs of pressure at all (no sticky bolt, ejector marks, bolt face marks, cratered or flattened primers, etc.) was 46.0gr. (over max per Berger book but barely over 45.5gr. max per Hodgdon manual w. 115gr. SBT)
I fired two rounds of the 39.0gr. loads to verify dope and POA and was within 2" of desired impact with just guessing at velocity. Not bad.
My nodes were as follows:
Highest impact on target but middle velocity of all 15 rounds (5" above POA) with about .355" of total vertical dispersion
41.5gr @ 2817fps
42.0gr @ 2875fps
42.5gr @ 2922fps
Lowest impact on target but nearing highest velocities of all 15 rounds (4" below POA) with about .225" of total vertical dispersion
44.0gr @ 3073fps
44.5gr @ 3091fps
45.0gr @ 3146fps
The rifle:
Rem 700BDL SA
23.5" Shilen barrel 1-10" twist #4 sporter contour
Custom English Walnut stock w. fully glass bedded action & pillars & free floated barrel
Timney trigger @ 2.5#
Vortex Viper HS 4-16x50 @ 16 power
Front bipod, rear bag prone position
Weather:
60-65° F over the coarse of 2 hours shooting time
Winds fairly steady 5mph @ approximately 10:00
Baro: 28.82
Altitude 1563' AMSL
I have taken game with this rifle on several occasions, and my older daughter has as well. Loads were 100 SMK @ 3240fps and 100 TSX @ 3290fps. I also had an 85gr. NBT @ 3380fps load, but have stopped using it for the SMK loads. Much more accurate load.
This rifle has always been faster than published loads for some reason.
I am going to work up both nodes, but I am leaning towards the faster node, as this is for a hunting rifle, and looking at the energy differences, I can get another 125 yds. or so to remain above 1000# of kinetic energy.
The cartridge: .250 Ackley Improved 40°
Case capacity: case capacity for .250 Savage AI is 51.92 gr of water. (Case capacity for .257 Roberts is 52.43 gr of water for reference)
I used the .257 Bob as a loose guide for the new load workup. I have some great loads for a 100 SMK and 100 TSX already, but wanted to work up a 115 Berger VLD load.
The 115 Berger VLDs are seated very long (@ 2.754" COAL and boat tail base is right at the shoulder/neck junction) and were jammed about .010" into the lands for the ladder testing, meaning once I start seating depth adjustments, pressures should go down a bit (being aware I will be encroaching on case space though).
Powder is IMR4350
CCI BR-2 Primers
Starting load was 39.0 (about middle of the .257 Bob loads per the Berger book w. starting at 37.5gr. and under starting loads per Hodgdon manual of 41.9gr.)
Worked up in .5 grain increments
Ending loads with no signs of pressure at all (no sticky bolt, ejector marks, bolt face marks, cratered or flattened primers, etc.) was 46.0gr. (over max per Berger book but barely over 45.5gr. max per Hodgdon manual w. 115gr. SBT)
I fired two rounds of the 39.0gr. loads to verify dope and POA and was within 2" of desired impact with just guessing at velocity. Not bad.
My nodes were as follows:
Highest impact on target but middle velocity of all 15 rounds (5" above POA) with about .355" of total vertical dispersion
41.5gr @ 2817fps
42.0gr @ 2875fps
42.5gr @ 2922fps
Lowest impact on target but nearing highest velocities of all 15 rounds (4" below POA) with about .225" of total vertical dispersion
44.0gr @ 3073fps
44.5gr @ 3091fps
45.0gr @ 3146fps
The rifle:
Rem 700BDL SA
23.5" Shilen barrel 1-10" twist #4 sporter contour
Custom English Walnut stock w. fully glass bedded action & pillars & free floated barrel
Timney trigger @ 2.5#
Vortex Viper HS 4-16x50 @ 16 power
Front bipod, rear bag prone position
Weather:
60-65° F over the coarse of 2 hours shooting time
Winds fairly steady 5mph @ approximately 10:00
Baro: 28.82
Altitude 1563' AMSL
I have taken game with this rifle on several occasions, and my older daughter has as well. Loads were 100 SMK @ 3240fps and 100 TSX @ 3290fps. I also had an 85gr. NBT @ 3380fps load, but have stopped using it for the SMK loads. Much more accurate load.
This rifle has always been faster than published loads for some reason.
