Re: Help me build a 1 mile rifle...
Well Gents (and I use that term with some trepidation on this thread),
I was extremely excited a few minutes ago when I tripped over this thread. I LOVE this stuff. I was terribly disappointed a few posts in when the bashing started. The main reason i chose this forum for my company's advertising dollars a year ago was the culture of the folks here. I was having dinner with Jim See at the Varmint Hunters jamboree in SD last year and he told me about LRH. We spent at least an hour discussing the pros and cons and the "culture" of the different serious shooting forums. I then spent a couple of months lurking here and was highly impressed with the genteel attitude of the members. I had never found another forum where rookies were treated with such respect and where gun and gear builders big and small shared their collective wisdom.
Thanks Shawn for getting it back on track!!!!
So please allow me to share my most recent experiences on this very subject. There are a huge number of variables to contend with but they are eminently within reach. I had a meeting about a month ago with Josh Ruby who runs North Texas Rifle Precision. I've known Josh for 5 or so years and shot many tactical competitions with him. He is running one of the best long range training facilities in the country. He does one on one training and hasn't gotten so big that he is cycling big groups of military and Law enforcement yet. He will be hosting his first tactical competition on Oct 1-2 and as part of the two day event, he is giving every shooter two shots at his 1780 yard target from a very stable two story tower. He has two pieces of steel, 20"x20" (1.1 moa) and a 36"x36" (2 moa). So that every competitor does not have to bring a mile capable rifle and so that they are not absolutely ruining his steel at closer ranges, he had us build him a dedicated one mile rilfe that everyone will shoot at the mile.
We sat for several hours discussing as many of the variables as we could think of and pouring over our ballistic calculators (Ballistic FTE on iPhone running the JBM calculator and set up for direct Density Altitude entry). What we came up with works and works really well. It is by no means the only solution so I will try to include the rationale for our decisions as well.
Caliber / cartridge choice
300 RUM - We considered several 338 ideas including Lapua, Edge and RUM and decided against them for purely financial reasons. It simply cost two to three times more per shot to launch these. Our desire was to let everyone shoot a platform that should they decide to jump in, they could actually afford to feed. We also considered several 7mm choices, all of which have already been mentioned. Most of these will also get there very well but downrange energy was important so that when the steel is hit, it moves discernibly for spotting / learning purposes. Simply put, 225 grain 30s hit a bit harder than 160 -180 grain 7s. Bottom line is that you need a BC of .670 plus going 3100 fps plus at 1000' DA. What you are looking for is not just a mile (1760 yd) launch but about 1900 - 2000 yds of supersonic flight so that you have some margin at the mile. Result - we have the new 225 grain Hornady match bullets doing 3175 out of a 26.5" Bartlein 5R tube. The load is 96.4 gr Retumbo with CCI primer in Rem brass. Tried Federal 215Ms and found them to create excess pressure a little to quickly. Surprised me a bit. Remington brass is borderline. Needs lots of prep. Wish Lapua made this case. And we discovered that the Hornady BC appears to be understated a little. They told me .670 and we are calculating an actual .690. Our load gave us an ES of 11 and an SD of 5.
Thoroughbred Action (a combination of all the good features of the Stiller Predator and Tac). One key ingredient is that the mag well opening is .130 longer than a standard Remington. This is irrelevant if you use detachable mags because they don't need the extra length but they also limit your COL. Our loaded COL was 3.81. We used Wyatt extended mag box with PTG BDL bottom metal. The Wyatt box is .110 longer than standard. All this allowed us to seat the bullets with the junction of the boattail and shank even with the junction of the neck and shoulder (or real close) so that the bullets aren't taking up precious case capacity. We are jumping .010 to the lands and I used a PTG match reamer. This works out to just about the perfect setup.
Although I personally like to kiss the lands for easy accuracy, it's not ultimately desirable for pressure and reliability. Don't want to stick one accidentally a bit too deep and have to un-chamber a live one in a hot chamber.
Bartlein 5R, 6 contour (Bartlein's contours are different than others) fluted finshed at 26.5", 10 twist.
McM A3/5 with adj LOP and Cheek bedded with g10 pillars and MarineTex.
Stiller 30 MOA base - a must have to get from a 100 yd zero to a mile with even the best glass. Our come up for 1780 was 56 moa on a 3000' DA day.
Nightforce 5.5-22x56 - The main point here is the 56mm obj. It is remarkably better at resolving long range in daylight than the same scope with 50mm objective. You need an optic with at least 110 moa total. Remember that you only get half of that for up and it takes about 5 - 8 moa to zero at 100 yards. The base makes it possible for you to be looking through the better closer to center part of the scope lens. An S&B or USO would also work great. We just like NF.
Tubb 2K Brake - a real touch of secret sauce. We tuned our load for low ES / SD then we used the T2K brake to tune the barrel. During load development we used two turns to get sub half moa and then when we began long range testing we put one more turn on it and Jay shot a three shot group with outside to outside of .4 inches at 100 yards.
I think the whole rig weighs in about 15 lbs although I haven't actually weighed it yet. Point is that it is easily man portable for position hunting /shooting.
Don't have any idea yet how these new 225 grain pills will perform on game. One thing I learned the hard way this year in South Africa is that I really like penetration. And I mean all the way in and out. I know it doesn't dump all the energy argument but it lets out more air and juice out of two holes vs one and if your placement isn't perfect (quite statistically possible at a mile), you get a nice blood spoor to follow after your 4 minute hike to a mile - haha - not happening in my remaining lifetime.
We had the huge advantage of exact known distance. Otherwise a world class laser is mandatory. Maybe the Zeiss binos will work. I haven't tried them to a mile yet on game or anything else. The Swaro monocular gets close but no cigar. The new relatively cheap Bushnell is getting some good press but I think the screen is too cluttered. Got get me a Vectronix ranger.
Best solution for spotter in my humble opinion is a pair of Canon 18x50 stabilized binos on a nice Manfroto tripod. Best kept secret out there. Talk about seeing mirage and spotting trace. Totally incredable. Not to mention glassing without fatigue (due to high magnification jitter) forever.
Build a really good .308 and send 1000s of rounds out to 1000 yards for practice in similar terrain. I used to get up before first light and drive to a little open piece of pasture on the west side of a hill, drop a bag of deer corn in about a 20 yard circle, get back in my Avalanche and drive across the little valley to the opposite hill at 650 - 660 yards. Point my truck at the target zone. Relax till the sun started to rise behind me while enjoying heated seats, light music and hot coffee on very cold mornings. Wait for a few doe to show up on the corn, climb up on the Avalanche rear deck with my favorite 308, bipod and rear bag and setup on the roof of the truck. Took some practice in the off season with a piece of steel but I got really good at first round hits on doe.
Decide what you want to do, make a plan, acquire the gear, practice - then just go do it!!!!!