Re: 7RSAUM Loads
I began load development yesterday from my new hunting rig for Colorado. I wanted to see where I was on velocity first before I started shooting for groups as I did not want to waste time / components finding a great group that was say 200 fps slower than the neighborhood I wanted to be in.
Barrel: 26” 1:9 5R SS Krieger with JEC Muzzle Brake. Chamber has a 0.180” Free Bore
Chronograph: CED M2 with IR screens 10’ from muzzle.
Climate: 80F 10’ above Sea Level
Loads:
Brass: New Nosler 7SAUM
Bullet: 168 Berger VLD Hunting
Primer: CCI BR2
Length: 2.190” base to ojive using a Sinclair comparator, 2.975" OAL. This is with a 0.050” jump to the lands.
Powder H4831sc
Grains FPS
58.0 2713 First round ever down the barrel
59.0 2686 Not sure why slower maybe because barrel is brand new?
60.0 2771
61.0 2829
62.0 2894
63.0 2963
63.5 2982
64.5 2975, 2961, 2973, 2957
65.0 3012, 3027, 3009, 3014, 3001 Slight Ejector marks on brass.
I did a retest with the same specs above except with a Remington 9 ½ Magnum Primer
64.5 2958, 2985, 2967, 2987 so not much difference than a “regular” primer
Powder H1000
62.0 2690
64.0 2800
65.0 2876 Case was basically full
Retumbo
63.5 2750
65.0 2796 Case was almost full
So what I have determined is that for the 168 VLD H1000 and Retumbo are too slow to give me my desired velocity. I will retest with H4350 and go from there. I am sticking to Hodgdon Extreme powders as I do not want to have a great load at home (sea level and hot) and end up with a crappy one in Colorado (cold at altitude).
Climate: 85F 10’ above Sea Level Density Altitude 1725'
Powder H4350
Grains FPS
56.0 2812
57.0 2857
58.0 2892
59.0 2974
60.0 3035, 2987, 2976 Very Slight Ejector Marks
60.5 3011, 3024,3049, 3037
61.0 3077, 3094, 3089, 3030, 3038
61.5 3088, 3112, 3080 Ejector Marks
I did a retest with only 0.020” jump or 2.220” base to ojive, 3.005" OAL.
61.0 3039, 3036
61.5 3106, 3113, 3081