Ridge Runner

probably not what you want to hear, but it will save you money, and cut your learning curve in the long run.
If its your first steps into the world of long range, forget the lazer flat trajectories, the "up" is the easiest part of the whole deal, lazer flat means big cases, small bullets, lots of throat erosion.

When I started I kept thinking man a bigger case and faster bullet will get me where I need to go.....I bought a 7mm mag, did ok to 450 yards, so I bought into the weatherby hype, bought a 270 Bee, did ok to 450 yards, so I went a step higher on the ladder and ordered a full house custom, a Bansner UR-1 chambered 7mm STW, still I was stuck at 500 yards.....how could this be? that 300 fps extra velocity only gives you another 50 yards max range, then I learned the #1 rule in long range shooting
In the world of long range, BC outruns velocity every time
cartridge is not important, a high BC bullet drops and drifts 30% less than a standard bullet at ranges beyond 500 yards
example
270 weatherby, 140 gr bullet, 3150 fps, sierra 140 HPGK sighted dead on at 250 yards, lets call the BC .366
at 750 yards that bullet is 126.5" low at 750 yards
same rifle, sight in and conditions only with a berger bullet of 140 gr, with a BC of .487 it drops 23" less at the same distance
jack that up to a 150 gr, with a BC of .531 and though it has a lower MV, it still drops 23" less than the sierra, or the same as a 140 gr berger at 3150 fps. yet they both retains almost 400 ft/lbs more energy at 750so what would you rather shoot a deer with a bullet that drops 126" at 750 yards and gets there with 668 ft/lbs of energy, or one that drops 103" and retains over 1000 ft/lbs of energy.

get a ballistic program and play with some numbers, take the load you shoot and just raise the BC on the bullet and check the drop and drift beyond 700 yards, you'll me surprised what you discover
and remember this, any 2 given bullets if they have the same BC, and launched at the same velocity, drift and drop exactly the same reguardless of weight or caliber
more to come
RR

jeepkid

That's the first thing you taught me years ago James...BC out runs velocity every time! Having both is always pretty awesome too

Ridge Runner

It is at that, but of all factors affecting bullet flight, BC has the greatest affect.
RR

Ridge Runner

to give real world examples here are the drops for 2 loads I shoot a bunch
all conditions are the same, both rifles sighted in at 300

6.5 Gibbs, 140 berger, MV 3180 fps, proven BC .7
both rifles fired in a 5 mph full value wind left to right
drop at 800 yards is 95.53" (11.5 MOA) drift is 14.19" time of flight is .92 sec.
bullet retains 1419 ft./#'s of energy

7mm Allen Mag, 160 nosler accubond, MV 3550 fps, proven BC is .58
bullet retains 1757 ft./#'s of energy
drop at 800 yards is 81.49" (9.75 MOA) drift is 15.9" time of flight is .857 sec


lets sum this up
700 shots and you either setback or rebarrel the 7mm, the gibbs will last 2500 because it burns about 1/2 as much powder, the 400 fps advantage in MV the 7mm carries amounts to 6 clicks of the scope but the 6.5 drifts 2" less. so to save those 6 clicks each shot at 800 you will rebarrel the allen 3 times, burn twice the powder in the course of 2500 rounds from each rifle. and the gibbs still retains well over enough energy for a clean kill at that range. but the 7mm will get the bullet there 63 thousanths of a second sooner
RR

Sheridan

Okay - BC is king, I agree.



Keep it coming, I am about to put together a 7MM RM right now.....................?!?!

Ridge Runner

In a 7RM, I would look for an 8 twist, that way you could shoot the 160 class bullets and the 180 berger, you would be surprised how well even the lighter bullets would shoot, you may lose 60-75 fps velocity over a 9 twist but the faster twist also helps with expansion and as long as the bullets jacket can stand the RPM's you will not over stabilize them.if your wanting to shoot the thin jacketed vld's I would opt for button rifling over cut rifled.
have a friend that I've been working with who does well with a 7 mag and 162 a-max's, I would go at least 28" on the barrel and prefer 30" if your not wanting a mountain rifle, keep it around 10# if you shoot off a bipod, preload the bipod, next to proper setting of the parralex it will help most to make your shooting consistant.
RR

bronko22000

RR I didn't take you as a long range shooter with an ID like that. I envisioned you as a short range (<100 yards) still hunting the mountain tops for game!
Long range often intrigued me but I just never had the $$ to pursue it properly with the right equipment even though I've taken several animals in the 300 - 500 yard mark. All with a Rem 700 in .270 Win and 130 gr. Nosler Ballistic Tips.

DJfan

Forgive this rookie, but what is BC?

Also, if you could address some of the other technical terms, I know I would appreciate it. I live in elk country, but have arthritis in my hips, so long shots are necessary. I have wanted to get into long range shooting.

Thanks for any time on this.

Sheridan

This site might be of some help to you along the way.............

http://www.chuckhawks.com/bc.htm

Ridge Runner

I acquired that name chasin bear hounds in my youth, use to be said if ya wanna know where he is, look somewhere between the bear and the first few dogs, but since `1981 or so I have been ate up with shooting extended distances, have taken a handful of deer beyond 1000 yards, 2 beyond 1200, just something I decided many years ago to learn to do, not easy for a backwoods hick, so if I can do it, anyone can.
RR