Mass vs. Velocity?

[andersonjk4]

Also, in reading these replies, it looks like many people are trying to decide on one caliber over another caliber. 

To me that is a personal choice based on:
-comfort with recoil
-confidence in the rifle
-etc.

The more interesting question to answer (I think), is that if you hold cartridge constant, what is better, more mass or less mass?

It should be a given that, within the legal limits of the law, folks should shoot what they have and what they feel most confident in putting a bullet on target with.  Once you make that call, what do you look at then?  Mass, bullet construction, and if you are a long range shooter, trajectory.

  That is why I posted the question.  I'm set on using my .30-06 (at least for now) and using it for both whitetail and elk.  I have been shooting it for close to 15 years and am very confident with it.  I was just pretty surprised at first when I saw guys using 120 grain bullets for elk, becasue I was previously in the mindset that heavier was better for bigger animals. And I've been toying with trying something besides the 165 grain Nosler balistic tips I currently use for both species.  I've been shooting the balistic tip, because they are very accurate in my rifle, and while I have no complaints about there performance killing game, I also haven't really been blown away by their performance either.  So that is why I've been thinking about trying out some different bullets and that inevitable leads to the question of how heavy of bullet should I use (and for the .30-06 there is a very wide range to choose from). So I decided to see how many other guys (if any) were using "lighter" bullets for elk and having success.     

[high country]

consider retained weight and bullet upset between the 165 bt and say a barnes tsx. the tsx will typically retain very close to 100% of its weight while the bt never will. the bt gets the nod on bc, but can't compare in terms of penetration.
 
that said, I would never fail to endorse a guy using a 06' on elk, I would not sugest a B tip, but they have worked for a great many though.

[Curly]

If I were going with a 30-06 for deer and elk, I think I'd choose the 150 gr Barnes TSX or Nosler E tip if they shot acceptable groups.  No reason to switch to a heavier bullet for elk than for deer if you go with a good bullet that will retain its weight.

Now, the article that was mentioned where the guy is using a .257 Weatherby.........I think he is making a mistake with using the 120 gr Partition (he should be using a bullet that will hold together better than a Partition will).

With the advent of bullets like Barnes TSX, the thinking of heavy for caliber bullets can be thrown out the window pretty much.

[GoldTip]

I would never recommend using a Nosler ballistic tip on elk, even if you could find a 200gr version for your 30-06, in fact I would strongly advise against using a Nosler Ballistic tip on elk.  If you want to use a polymer tipped bullet on elk, stick with a bonded bullet such as the Accubond or the swift scirocco.

[Rob]

How about asking this question another way.

if:
1.  you decided to shoot a 30.06 Springfield because you have one, you like it, and it shoots well

-and-

2.  You have tried 150, 165 and 180 grain bullets in a brand/style you feel is effective at killing, and found them all to group well from your gun.


-and-

3.  You are targeting Elk.


What bullet would you shoot and why?

[high country]

I will take a peek at the bc's of each and velos of each....from there I can decide which is the best bang for the buck at the distances I shoot.

[Rob]

What attributes of BC and velocity would you be looking at to make your decision?  What role does distance play in your decision making process?

I see the variables that you would be looking at, but what sways you one way or the other?

[high country]

If a 180 gr bullet gives me a bc advantage over a lighter bullet, and I do not pay a large elevation penalty, that would be my choice. It is very easy to learn your vert corrections, wind is the tough one. If I am paying a 12" elevation penalty at 400 yds to save 2" of windage the lighter bullet gets my nod. I see it as simple math.

Stretch the range over 500 and my rules change to highest bc premium I can find.

[Rob]

I asked about BC as I have been looking at this over the past couple months getting ready for a hunt in 2012.  I have come to a conclusion that has kinda surprised me so I am trying to poke holes in my conclusion. 

Here is my conclusion:  In terms of Trajectory, BC is largely irrelevant in hunting situations if the shooter plans to shoot at distances under 350ish yards.  Here is why I came to that conclusion.  First the assumptions:
-I am holding MV constant at 2700 FPS.
-I am comparing two bullets, both in .308 caliber but with different BC’s
-I went with a heavy bullet as I figure this will have the worst trajectory data.
-I am taking bullet performance out of the equation for this compare (i.e. how well does the bullet hold together, how well does it expand, etc)  I am only interested in seeing how BC impacts trajectory over distance.

So I am comparing a Barnes Solid in 220 grain/.308 caliber traveling 2700 FPS with a Sierra HPBT Matchking in 220 grains also traveling 2700 FPS.
-The Barnes has a BC of .305
-The Sierra has a BC of .629
See the table in the attachment below.  (I ran these #’s in the phone app “shooter”)  This table tells me that even though these two bullets are aerodynamically very different, they will shoot within 3 inches of each other out to 325 yards. 

Now, in typing this up and looking at the numbers, I have just realized something very interesting (again, probably a penetrating insight into the obvious for everyone else, but this kinda stuff is new to me so humor me).  This should have been very obvious to me, but it was not until I saw the #’s.
While the two bullets are pretty close from a trajectory view point, look at the velocity #’s!  The poor BC bullet is moving 420 FPS slower at 325 yards than the good BC bullet!  That is a 20% difference!  This translates into a reduction of 841 foot pounds of energy, and a reduction of 13.2 lb/fps in momentum. 

Now those are significant #’s…
So I guess I have revised my view after looking at this stuff.
When planning to shoot under 350ish yards:
1.  Choose the heaviest bullet that shoots well for your gun
2. BC does not matter much when it comes to bullet drop at those ranges
3. BC does matter in terms of velocity which translates into energy, momentum, and penetration.
4.  So pick the heaviest bullet with the best BC.

[whacker1]

I asked about BC as I have been looking at this over the past couple months getting ready for a hunt in 2012.  I have come to a conclusion that has kinda surprised me so I am trying to poke holes in my conclusion. 

Here is my conclusion:  In terms of Trajectory, BC is largely irrelevant in hunting situations if the shooter plans to shoot at distances under 350ish yards.  Here is why I came to that conclusion.  First the assumptions:
-I am holding MV constant at 2700 FPS.
-I am comparing two bullets, both in .308 caliber but with different BC’s
-I went with a heavy bullet as I figure this will have the worst trajectory data.
-I am taking bullet performance out of the equation for this compare (i.e. how well does the bullet hold together, how well does it expand, etc)  I am only interested in seeing how BC impacts trajectory over distance.

So I am comparing a Barnes Solid in 220 grain/.308 caliber traveling 2700 FPS with a Sierra HPBT Matchking in 220 grains also traveling 2700 FPS.
-The Barnes has a BC of .305
-The Sierra has a BC of .629
See the table in the attachment below.  (I ran these #’s in the phone app “shooter”)  This table tells me that even though these two bullets are aerodynamically very different, they will shoot within 3 inches of each other out to 325 yards. 

Now, in typing this up and looking at the numbers, I have just realized something very interesting (again, probably a penetrating insight into the obvious for everyone else, but this kinda stuff is new to me so humor me).  This should have been very obvious to me, but it was not until I saw the #’s.
While the two bullets are pretty close from a trajectory view point, look at the velocity #’s!  The poor BC bullet is moving 420 FPS slower at 325 yards than the good BC bullet!  That is a 20% difference!  This translates into a reduction of 841 foot pounds of energy, and a reduction of 13.2 lb/fps in momentum. 

Now those are significant #’s…
So I guess I have revised my view after looking at this stuff.
When planning to shoot under 350ish yards:
1.  Choose the heaviest bullet that shoots well for your gun
2. BC does not matter much when it comes to bullet drop at those ranges
3. BC does matter in terms of velocity which translates into energy, momentum, and penetration.
4.  So pick the heaviest bullet with the best BC.

I agree with your outcome.

That is similar to what I learned in the last several  years in picking bullets for 270 and 300 RUM.  For the layperson, the Ballistic Coefficient is its ability to fly and how well as compared to another bullet.  This took me quite awhile to understand and wrap my arms around, but to state in terms that most can understand.  The better a bullet fly's - the better it will retain energy, retain velocity, and buck the wind.  If you compare the ability for a round ball to do these three things as opposed to modern bullets, it becomes very obvious.  The round ball loses velocity quickly, which results in the loss of energy.  With it being a slower moving object and thus in the air longer, the wind will have more impact on it. 

[high country]

Rob, plug a 10 mph full value cross wind in and see what happens. That loaf of bread will go off like poor golf slice.

[Rob]

That is interesting.

Out to 250 it is not too big of a difference, but beyond that it is substantial.

I added some color to show where I start to worry.

[Rob]

I still think energy loss is the bigger argument for a better BC bullet.  at just 100 yards, you are loosing more than 10% of your energy when comparing these two bullets.

but the drift should not be overlooked.

[whacker1]

I still think energy loss is the bigger argument for a better BC bullet.  at just 100 yards, you are loosing more than 10% of your energy when comparing these two bullets.

Now try it with a 35 mile our wind like you might run into in the high country or the plains. 

[Rob]

That's probably moot for me, as I would not attempt a shot in that kind of wind.  but I am sure it is even more pronounced.

Besides, I have convinced myself in the first run of the #'s that a better BC should not be overlooked.

But I would still choose a heavy bullet over a light one for shots under 350 yards based on penetration!