Hunting Bullets and BC's

[ohiohunter]

Well I'll be a monkeys uncle...

Even w/ the advertised bc's it works out to be about the same at 1k in my bullet drop app. You guys are making my brain hurt... Now I'm looking for lighter bullets for fclass. The whole time of flight thing.

Some guys were talking about pushing the 6.5's fast enough to out perform the 215's.. bergers that is. Food for thought i guess.


Ridge.. what I was suggesting is why use berger vld (not their slickest design) vs nolser's ablr (their slickest)... Compare the 168 ablr vs 150 ablr, but it still seems to be a moot point.

 

[MMERSS]

Great topic. IMO it depends. Form factor, SD, energy both ends, velocity, and seating depth to name a few should be factors with the decision all the while not compromising accuracy. Considering all else equal, the higher BC bullet of same weight and velocity will drift less at 500 yards. A significant difference in BC may only equate to a 10% or slightly less difference in hit probability depending on the size of the target but why leave this on the table? This would be the same as leaving velocity on the table, again considering all else equal.

 

[Ridgerunner665]

The whole time of flight thing.

Form factor,

Exactly...I think...after reading Bryans books (all of them), parts of them multiple times, so it sinks in.


Now, given what we are agreeing on thus far, and standard rounds (280 Ackely, 30-06, 270 Win, etc.)...it all goes out the window if you move out to ELR (1,200+ yards) with a big magnum round...then a person is better off with the highest BC bullet they can get going at least 2,850 fps or so (as was mentioned earlier)

Its all in that time of flight number...err, well...better way to put it is, don't overlook the TOF number.

 

[MMERSS]

Well I'll be a monkeys uncle...

Even w/ the advertised bc's it works out to be about the same at 1k in my bullet drop app. You guys are making my brain hurt... Now I'm looking for lighter bullets for fclass. The whole time of flight thing.

Some guys were talking about pushing the 6.5's fast enough to out perform the 215's.. bergers that is. Food for thought i guess.


Ridge.. what I was suggesting is why use berger vld (not their slickest design) vs nolser's ablr (their slickest)... Compare the 168 ablr vs 150 ablr, but it still seems to be a moot point.

This topic is covered in one of the Applied Ballistics books. Considering same energy at launch, the slower velocity higher BC bullet will drift less than the faster velocity lower BC bullet at 1000 yards...or 500 but not as much. SD and energy are more of a consideration at 500.

 

[Ridgerunner665]

This topic is covered in one of the Applied Ballistics books. Considering same energy at launch, the slower velocity higher BC bullet will drift less than the faster velocity lower BC bullet at 1000 yards.

Thats "generally" true...but its a little too general to fit in all instances (I think, based on my understanding of Bryan's work)..a lighter bullet with a high enough BC launched fast enough will run right along with the heavier bullet to 1,000 yards...this is where form factor and TOF have to be accounted for.

The 150 ABLR in the 280 Ackley is a prime example of this...very good form factor, still light enough to launch fast, and enough BC to hang on to it pretty well....it takes more than 1,000 yards for the heavier bullet to best it by any significant amount.

150 Nosler ABLR (G7 .295)


180 Berger


What I have not calculated is how much the 2" drift difference effects the hit probability...

 

[MMERSS]

Thats "generally" true...but its a little too general to fit in all instances...a lighter bullet with a high enough BC launched fast enough will run right along with the heavier bullet to 1,000 yards...

The same could be said about the heavier bullet, if launched fast enough! Equal energy comparison at launch betwen the two is equal playing grounds.

What is the kenetic energy of the bullet leaving the muzzle with the two examples given? Are they the same? Use same energies in an example and see which drifts less.

 

[Ridgerunner665]

I did make the launch energy equal (within 1 pound or so)...still only a 2" difference at 1,000 yards...according to the app anyway.

I did add that after the first edition of the post...may have been adding it while you were typing

And you're not wrong...regardless of bullet weight...TOF, form factor, and velocity ALL have to be taken into account...just looking at the highest BC or the highest muzzle velocity isn't enough...there's more to it than that.

 

[bigngreen]

I think some of us use BC to describe what we're liking in terminal performance, wrapping up BC, sectional density, impact velocity as well as ballistics and broadly talking about it as BC. I've ran a number of rifles with light fast bullets and heavies at moderate speed both bullets being as good a form as possible in their weight class, both ways look equal on paper but paper and computer work is all fun and good but when I put bullets on game, close and far big and smaller game I've been more impressed by what we'd describe as high BC bullets.

I recently started shooting the 308 again because of the terminal performance and ballistics I'm seeing by going to the 215 Berger, even only at a little over 2400 fps it simply destroys every thing else I've shot in my 308 and terminal performance has been unreal. I think we tend to describe this simply by saying BC.

 

[MMERSS]

I did make the launch energy equal (within 1 pound or so)...still only a 2" difference at 1,000 yards...according to the app anyway.

I did add that after the first edition of the post...may have been adding it while you were typing

And you're not wrong...regardless of bullet weight...TOF, form factor, and velocity ALL have to be taken into account...just looking at the highest BC or the highest muzzle velocity isn't enough...there's more to it than that.

2" may not seem like much. Factor in the SD and energy increase as well and all the littles start to add up.

 

[RockyMtnMT]

I picked a well known ballistics calculator and well known bullets to compare. Yes I have used several ballistic calculators over the years looking at these things.

As I said in my 1st post, the longer the range the more the bc matters. Kind of my point of interest for this thread was to talk about how far out does it need to be for bc to become relevant. Guys always talk about that "quick shot that jumps up". That is where the flatter bullet comes in. No time to range. Or just enough time to range and know that you can hold on and make the shot. The closer the range the less time is available. Some guys carry two different bullets and loads for this reason. Some say speed kills. I'm not so sure that it should so quickly be dismissed. I picked the 300wm as a middle of the road for the comparison. Not too many years ago it was kinda the big boy. You start looking at the big mags and how they can push the smaller bullets and suddenly 800 plus yards becomes not so far out. It starts pushing 2000 yards for the heavies to catch up.

I just hate to see guys being told that if they run anything less than the highest bc bullet they are making a mistake. Even on this site that is dedicated to long range hunting, most of the membership here hunts under 400 yards. (I think I saw that number in one of Len's poles. Correct me if I am wrong.)

Maximum point blank range becomes a very significant number for many hunters based on their ability, style, and geography. Time of flight also becomes a significant element.

Just because my long range is 1000 doesn't mean that that guys 400 isn't long range. And those guys that are hunting at the mile range doesn't make my 1000 short range.

I would have to say that the thread has made the over for staying civil.

Steve

 

[stonehands1]

Looking at my charts, looks to me that the 150 is king to about 600 or so then the 190 takes over. Unless I'm planning a hunt where I know I'll be shoot more than 6-700 then Imo less recoil and flatter shooting wins every time.