Apr 27

Apr 27 My First Precision Rifle Match: Part 2

Bad Data, Good Data and Some Last Minute Fixes

The next step after getting my rifle, optic and ammo figured out was getting some good ballistic data. My favorite way of doing this is using Gunwerks G7 ballistic software, available for free HERE. I had used it on 4-5 other rifles and it had always came out great! They have also made a good how-to video for their software and the validation process.

To start off, I took the muzzle velocity off the box of ammo I was using, which is Hornady's American Gunner 6.5Cr 140gr HPBT at 2690fps. I plugged all of that data into the Gunwerks program and got a drop chart printed off. From there I headed out to the range.

Second Target @950yrds for velocity validation.

I set 2 targets up, one at 600 yards and the next at 950 yards. Next I fired 5 shots at each target. Each group (no pictures of those, sorry) came out higher than my aiming point. I also . noted that at 950yrds, I needed exactly 7.4mils of elevation. So I took the average height in inches, went home and plugged it all into the "Validation" section of the ballistics program. Then I got my corrected velocity of 2830fps, which seemed very high for that load. Almost impossibly high. I figure something along the was way off. I kept getting 7.9 - 8.3Mils at 950. So I went back to the drawing board. I started from scratch on 3 separate ballistics programs, entering in all of the same information and I kept upping my velocity in each of them until I got 7.4mils at 950yards. I learned 2 things: 1) ballistic programs can be very different from each other in their calculations. 2) I really needed a reliable chronograph, like a Magnetospeed.

I found a deal online for the Magnetospeed Sporter online, ordered it and had it overnighted(got it 3 days before the competition). So I went back out to the range, fired 20rnds and recorded the velocities. Here is what I found out. My average velocity was 2695fps but my SD was 28...much higher than I like, but at this point (2 days out) I already had 200rnds of ammo and wasn't changing that. But I was definitely hand loading for the next match I compete in...

SIG Kilo2400, Savage Ashbury Precision Rifle and SIG Tango 6

I headed back out and did some more ballistics validation, this time I was on. I shot at 600yrds and 950yrds. Groups weren't the best, but would be acceptable for hitting a standard IPSC target at each distance. But then things wen't from good to bad.. I went to shoot a target at 1150 yards, but my scopes elevation travel ran out at 1050!? Knowing there were going to be many targets out to 1400yrds at my competition, this was bad. Upon further investigation I learned that Savage put a flat scope mount on these rifles. Not the usual 20MOA as most shooters would use. So I hunted down the only 20MOA rail for a Savage Short Action in Bozeman, MT. But yet again, another issue came up. This rail was extended and needed about 3/4in cut off the front because it was hitting the hand guard. So I took a Dremel to it and had it cut to length in no time. When I went to install it, I encountered yet another issue.. This rail was meant for an "open top" receiver, not the "closed top" receiver like my rifle had. From my research, bot rails were the same, except for a "lug" on the underside of the rail. With time coming down to the wire and ordering a new rail impossible at this point, I went ahead and ground the lug off. Luckily, it mounted up perfectly and is working out great.

Different Savage action types. I think the top one is referred to as their "Target" action.

From here I remounted my scope, went to the range and re-zeroed my rifle, took some shots at 600yrds to confirm zero and tested the scope travel out. I didn't get a TON more elevation, but I now have enough for 1400yard shots. Now, I was ready(ish) for the competition.