So please correct me if I'm wrong...

[rockstar.esq]

I've been reading up on ballistic coefficient as it relates to long range (1000yd) shooting. Thus far I've come to understand that bullets with higher B.C.'s equate to streamlined bullets that drop and drift less than bullets with lower B.C's. So far so good, now I look into the history of long range shooting and I see the .45-70 was/is used by BPCR shooters for 1000yd shooting to great effect. This leads me to wonder if consistency should carry more weight than the ravenous debating about B.C. and sectional density. I understand that Higher B.C.'s and S.D.'s often add up to flat trajectories that don't drift much in the wind. All of which would make the theoretical "window" into which all centrally aimed shots would fall as small as possible. How then do folks explain how the buffalo bore shooters do it? Add to the mix the silohuette shooters who're knocking over wee targets with revolver cartridges at 300 yards? I guess my new position is that the study of exterior ballistics certainly has it's interesting tidbits but it doesn't seem so significant that most long range shooters would need to obsess over them. I'd love to hear from all of you. Especially if I'm mistaken about something. Thanks in advance.

 

[Ol` Joe]

On the target range you shoot at a known distance and have your sights set for it. There is no "guessing holdover" as there is in the field. The guys that do this (both long range hunters & shooters) know their rifles and a big part of their ability to win comes from being able to read the wind and adjust their sights for conditions. It isn`t just the equipment the user plays a big role too.

 

[45crittergitter]

BC and accuracy aren't directly related. As Joe said, if you know the range and your trajectory, the most accurate combination is what you want, not necessarily the flattest shooting one. However, given equal accuracy potential, a higher BC round will likely give better target results, due to minimizing the effects of wind, range error estimation, etc.

 

[Old Time Hunter]

This might be too much of an extreme, but does wind affect a feather or a bowling ball more? In long distance shooting, even if the 100 grain bullet is more aerodynamic, eventually it's velocity reduces to a point where any resistance from any non-parallel direction will have more effect on the direction than a 535 grain bullet moving at 1/4 of the velocity. Flat trajectory might be the cat's meow out to maybe 300, 400, or even 500 yards, but there is not a projectile today that is absolutely flat to 1000 yards. Therefore, why fight physics, if you are going to have a trajectory, go with the weight instead of the speed.

 

[browningguy]

For long range shooting BC and SD certainly make a difference. Has anyone won Camp Perry with a 45-70 lately?

No one ever said you could not shoot accurately with the 45-70, but you can do it easier with one of the newer cartridges.

 

[Old Time Hunter]

I dunno browning guy, been out to Drummond and the wiz bang, super dupper, Camp Perry dudes had no problem getting to the little cast iron figures at 1k, but could not knock them over. At least with their .22-250 and 7mm-06's and such. My previous post did not necessarily imply .45-70's, it was just a bullet weight vs. drift discussion.

 

[Jim Watson]

A .45-70 will do amazingly well at 1000 yards (.45-90, -100, and -110 do even better) but you do not see them in direct competition versus even .308s. Accuracy standards are relative to the capabilities of the equipment.

A 500 gr .458" at 1200 fps is blown nearly twice as far by the same breeze as a 175 gr .308" at 2700 fps.

A very good .45-70 will approach MOA accuracy, but Pedersoli has given out darned few of their MOA Challenge plaques for BPCRs (any make) that will average one MOA or smaller for four consecutive five shot targets.
No highpower target shooter will fool with a rifle that will not stay well under MOA under good conditions.

 

[Old Time Hunter]

Maybe true Mr. Watson, but which one will have a tendency to follow it's course more? The 500gr @ 500fps or the 175gr @ 1000fps. Do the math.

Regarding the matches, do the .308 shooters use iron sights?

 

[Jim Watson]

I've DONE the math, or rather Sierra Infinity did it for me.
What do you mean by "follow it's course more?" What do you mean by 500 fps and 1000 fps? The .45 arrives at 1000 yards at 683 fps, the .308 at 1243 from Infinity calculations. A 540 grain .458" Creedmoor bullet would do better, but not a lot better.

The .45-70 is deflected more by wind and is not as accurate grouping as a .308 with equal quality ammunition of the appropriate types.

Either calibre can be shot in competiton with scope or iron sights. Irons are more usual, you have to be in the rather sparse BPCR scope divison or Highpower any/any (any gun/any sight) or F-class to use a scope in NRA competition.
From what I have seen, a good shooter can do as well with irons as a scope. My friend the AAA BPCR and Master Long Range shooter can. Don't know that I can, but I have not worked at it as hard and as long.