7mm Rem Mag - 150gr NP - ADI AR2213SC (H4831sc) - Low velocities
I'd really appreciate some help and/or advice.
I recently bought a Remington 700 XCR II in 7mm Rem Mag. 24" tube, 3.6" mag.
To date I have been breaking the barrel in (using factory ammo) and have just started reloading for it. The barrel has fired 120 rounds to date (excluding the tests below)
My first effort was a 150gr Nosler Partition in a Hornady case on top of ADI AR2213SC (H4831sc) powder and a Federal 215M primer. COAL was 3.280" (or 2.625" using a comparator), which gives me a seating depth 20 thous of the lands. Loaded rounds were then given a very light crimp with a Lee Factory Crimp die. Cases were FL sized to the point where the shoulder was bumped 2-3 thous and cases were trimmed to 2.490".
I loaded 13 sets in 0.5gr increments from 59gr to 65gr. The powder charge was the only thing that was changed between all the sets. Each set consisted of 4 rounds.
@59gr according to the ADI Manual/Hodgdon website should have produced 2775fps. I got 2572 avg.
@61gr according to the Nosler reloading guide #6 should have produced 2985 fps. I got 2765 avg.
@62gr according to the ADI Manual/Hodgdon website should have produced 2956fps. I got 2718 avg.
@63gr according to the Nosler reloading guide #6 should have produced 3023 fps. I got 2817 avg.
@66gr according to the Nosler reloading guide #6 should have produced 3075 fps. I got 2925 avg.
I got 3 loads of interest.
One group of 1/4 inch @2633 fps. ES=63, SD=25.4. Good group, but way too slow to be usable and poor ES/SD.
One group of 0.8 inch @2817 fps. ES=12.4, SD=5.4. Acceptable accuracy, but good ES/SD. Was hoping for more speed though.
One group of 1 inch @2886 fps. ES=30.2, SD=13.6. Acceptable accuracy, but the pace is getting towards what I was expecting.
I have another 50 of these projectiles and would really like to try and get more from them. I tend to feel that trying a different powder may be worth while as I really would like to get closer to the 3000fps mark, but I'm unsure which way to go. Do I try a faster powder such as AR2209 (H4350), or a slower powder such as AR2217 (H1000) or Retumbo. I would prefer to only use temperature insensitive powders as I hunt in both summer (25-30 deg C) and winter conditions (sub zero deg C).
Also, could anyone explain why I seemed to constantly get 200fps less than that the book said I should expect. I think that 200fps is quite a lot. Is it the 24 inch tube, or is something else at play? As a further point of interest, I chronied some 162gr Hornady Superformance Factory Ammo, and you guessed it ... 200 fps below what the ammo box claimed. Box claimed 3030fps, I got 2815fps as an average of 5 shots.