A few years back I commissioned a dear family friend of ours to build me a 308. I hoped for match precision on a practical platform. I provided him a SA 700 I bought for the project - from Walmart. A well respected barrel maker and 'smith, he was up to the challenge.
Time was not an important consideration for me, and, this or that circumstance arose, delaying the build. Two and a half years passed, but, I am the proud owner of an exceptional and uniquely crafted tool. Twenty-eight inches of heavy, hand-made barrel compliment the smoothest 700 action I have ever felt, chambered for my duty ammo - 168gr Federal GM Match. The Walmart special was certainly transformed and I was anxious to begin load development.
On 5/11, after a week of rainy weather here in SW Colorado, a sunny day allowed me to finish up my initial development. Satisfied with the results and all hand loads shot, I readied a box of Federal GM Match. My spotter and I located the only acceptable, safe target outside the confines of our range. The large rock was 4.98' tall and shimmered nicely in the morning sunlight on a dirt outcropping.
The only potential issue was the distance it sat from our location; 1660 yards. I reasoned, the ammo was free from a colleague, so, I had nothing to lose. What better way to spend a beautiful spring day?
I plugged conditions into my calc, and came up with a solution - 83 MOA elevation. I find inputting a wind value of 1MPH is easy to work with, so, as conditions change, I can simply multiply my 1MPH value by given speed (if same, or opposite direction). I ran the IOR out to near-max - 75 MOA. Math was never my strong suit, which makes for a little bit of frustration when dealing with maxed out MOA turrets and a MIL reticule, but I came up with the appropriate additional hold in MILs. I did the best I could reading mirage for distant wind (Ponderosa and rigid Juniper are not the most effective wind gauges) and held 2 MILs right.
First one was on its way. The calc reported a 3.67 second TOF, so, we waited....and waited. Nothing. I reviewed my data, wondering what variable I may have missed. The only thing I could figure was power temp. I had no idea what it was when I Chrono'd it a while back, but I knew it had been sitting in my garage and overnight temps where I live at 8000' ASL are still around 40 deg F. Being that it was still fairly early in the day and the box had been in the shade, I figured I would hold a bit higher and hope for the best. Wind seemed to be similar, so I sent the second one.
After a quick stretch and a sip of my beverage I figured I better watch for an impact. ;-)
To our suprise, that round hit about one MIL low, spot-on for windage. Our spirits lifted, I made the appropriate adjustment - deciding on a 4.5 MIL hold (equating to a total elevation adjustment of about 90 MOA!) - verified conditions, and sent a third round. It eventually made it all the way out there, dead center elevation, approximately .5 MIL right.
I again adjusted accordingly, and the fourth one was on its way. That one found its mark, slightly left of DC of the rock. I couldn't believe it. I squealed like a school girl.
My spotter, a good friend, colleague and capable shooter, decided he'd done enough spotting and wanted a shot at it. Behind the binos for the first time that day, I watched the vapor trail of his round arch so badly I figured a leprechaun would be on the other end. His 168 grain Sierra made landfall 8-10" right of mine and at dead center of our target.
I'm not sure if "elation" is the most appropriate descriptor here, but looking back as I type this, I think I would be embarrassed to see a replay of our reaction. Suffice it to say it was long, loud and extremely feminine.
I feel blessed that I get to spend the remainder of this shooting season (and many more to come) in God's country, getting to know this rifle.
That's awesome! Great shooting. I'm surprised that 168 didn't start tumbling as it went transonic... they have a tendency to do that. What was the computers estimated velocity at the target? Also, what BC did you use? A banded G1 or G7?
I was rather surprised as well. My program shows the 168 coming back through at about 1250 yards. The logistics here are more intricate than my meager knowledge of very basic ballistics. Everyone has to get lucky now and then, I guess...
My initial input showed a velocity of 953.9 fps at target, carrying 339.4 ft-lbs of energy. However, adjusted for powder temp, I showed 933.1 fps and 324.7 ft-lbs!!!
I used a banded G1, as it was all I had available.
It is a little breezy today, but I may try to get out and burn up more of this GMM.