Mass vs. Velocity?

[Kent Hunter]

I agree with Alan K. I shoot a Sako TRGS chambered in 7.82 (.30 cal) Lazeroni Warbird. It sends a 180gr .30 cal pill out of the bbl between 3400 and 3500 fps. I haven't shot any 200 grain bullets and chronographed them yet. I have shot more than a few deer and bear with the 180gr loads and three moose and one bison. I love the rifel and it has knocked the bejabbers out of every animal that I have harvested.

[dawei]

I hunt Roosevelt Elk in Western WA. I use the following guns and ammo.....
• Savage® 110L 30/06  w/180gr Speer® Grand Slam™ handload
• Marlin® 444SS w/290gr Beartooth® LFNGC Bullet handload

I use the 30/06 if I'm sitting a clearcut, otherwise it's the 444 most (90%) of the time.

[alwinearcher]

I'm going with the mass option..
338 edge shooting a 300 grn SMK at right around 2900..
I haven't gotten a chance to test it on elk or deer yet, but it puts the hurt of bears and 1/2" steel plates! 

[BULLBLASTER]

 

I'm going with the mass option..
338 edge shooting a 300 grn SMK at right around 2900..
I haven't gotten a chance to test it on elk or deer yet, but it puts the hurt of bears and 1/2" steel plates! 

I think that s the best of both worlds...

[alwinearcher]

I'm going with the mass option..
338 edge shooting a 300 grn SMK at right around 2900..
I haven't gotten a chance to test it on elk or deer yet, but it puts the hurt of bears and 1/2" steel plates! 

I think that s the best of both worlds...

Overkill? .... I think not!

[BULLBLASTER]

I'm going with the mass option..
338 edge shooting a 300 grn SMK at right around 2900..
I haven't gotten a chance to test it on elk or deer yet, but it puts the hurt of bears and 1/2" steel plates! 

I think that s the best of both worlds...

Overkill? .... I think not!

no such thing as overkill!

[andersonjk4]

Your figures are a little off. No .257 Weatherby will shoot a 140 grain bullet at 4000fps. If i remember correctly, 85 grain bullets are only going 3700? Someone will have to chime in on this...
[/quote]

You're right I was going from memory and didn't have the article infront of me.  I read the the article again and he was shooting a 120 grain Partition at over 3000 fps.  120 grains seems really light for elk to me.  But he is claiming its the best caliber for ALL western big game.  And he is the hunting editor for Outdoor Life, so that does have to say something about the cartridge. 

[andersonjk4]

I'm going with the mass option..
338 edge shooting a 300 grn SMK at right around 2900..
I haven't gotten a chance to test it on elk or deer yet, but it puts the hurt of bears and 1/2" steel plates! 

I think that s the best of both worlds...

Yeah I agree.  300 grains @ 3000fps!!! That is definitely the best of both worlds.  That would put the hurt on pretty much anything... including the shooter. 

[high country]

my answer is this, pick the bullets that work in YOUR velocity range, shoot well, and are as slick as possible. I have killed elk at better than 300yds with a single pass through from a 257roy launching a 100gr tsx at a measured 3600fps and I have killed them with a 300rum launching a few different 180gr bullets over the years at measure velos from 3200-3350. I have also seen elk take a 338 rum for a walk and the elk next to it flop from a 270 win....same distance, same day....heck, same time. both were solid double lung shots, one elk just did not want to die.
 
I was totally impressed with the performance of the 257 roy, and I will carry it this year or a 243 as I am due for shoulder surgery in sept...dang it! I will not feel the least handicapped by either as I have found from my own expierience that a well placed bullet of sund construction for the velocity it is traveling will yeild good results.
 
in all honesty, from the 243 to the 338 you are talking about 95 thousandths of one inch. that is the thickness of a piece of chewing gum.....it is not worth arguing about. imagine if somone came to you and said you were a fool because your gun shoots a bullet the thickness of a piece of paper different then theirs.......it happens every day.

[Rob]

I have put a lot of thought into this topic this year.  I hunt with the premise/bias that there is no such thing as too much penetration.  Based on this, my view is, more mass is better with one caveat – Distance.  If you are shooting under 350 yards, then get the heaviest bullet you can find for the caliber you are shooting (that shoots well of course).  If you are shooting over 300 yards, then a lighter bullet should be considered to allow for a flat shooting bullet.  Here is the research that led me to this belief

Assumptions:
-You are shooting a rifle YOU already shoot well
-You are shooting a single cartridge and the only variable is the bullet weight and associated velocities.
-My #’s are for a 210 grain and a 250 Grain Barnes TSX in a 338 Win Mag.
-200 yard zero
-The gun you are shooting had the right twist to stabilize a heavier bullet.

First I looked at some key variables:
Muzzle Velocity
We all know what this is.  Generally, faster is considered better-but not always as accuracy and bullet performance can be impacted

Sectional Density
Best explanation I have heard is; which will penetrate deeper into the ground when dropped nose first from 10 feet, a two pound rod one inch in diameter, or a 2 pound rod that is 10 inches in diameter?  Answer:  the smaller diameter rod as it has less frontal surface area for the given weight.  To get the two rods to penetrate the same depth, you would need to significantly increase the weight of the 10 inch diameter rod.  Another way to look at this is, The more mass you have behind a smaller surface area, the deeper it penetrates when traveling at the same speed.

Muzzle energy
How much energy is a bullet carrying as it travels?  More energy generally = better penetration for a given bullet.
Momentum
This is the variable I had never looked at.  This explains why a slow fat bullet with low muzzle energy (think the 45 ACP) can penetrate better than a fast light bullet.  The higher the #, the more momentum the bullet is carrying.

Here are some stats I ran on the 2 .338 bullets:
210 Grain TSX:
-MV= 2850fps
-Sectional Density = .263
-Muzzle Energy = 3788 Ft/Lbs
-Momentum = 85.5 lb/fps

250 Grain TSX:
-MV= 2700fps (5% slower than the 210 grain)
-Sectional Density = .313 (20% greater than the 210 grain)
-Muzzle Energy = 4048 Ft/Lbs (6.8% greater than the 210 grain)
-Momentum = 96.4 lb/fps (12.8% greater than the 210 grain)

So what this tells me (rounding the #’s) is that a 20% increase in bullet weight, will give me 7% more energy, and nearly 13% more momentum.  All this translates into more penetration.  An added benefit of a bullet carrying more momentum is that it is less likely to deflect should you hit a twig on the way to the target or a bone within your target.

But what about trajectory?  (Inches of drop for given yardage by bullet type)
Yards   210 Grain   250 Grain   Difference
50   0.7                0.9                 0.2
100   1.8                   2.1                 0.3
150   1.6                1.8                 0.2
200   0                0                         0
250   -3                -3.4                 -0.4
300   -7.8                -8.7                 -0.9
350   -14.2                -15.8                 -1.6
400   -22.7                -25.1                 -2.4
500   -46.2                -51                 -4.8
600   -80.2                -88.3                 -8.1
The table above indicates that with a 200 yard zero, the bullets are within one inch of each other out to 300 yards.  The lighter bullet does shoot flatter, but I don’t really see a noticeable difference until around 400 yards or so.

All this has led me to believe, that if you plan to take shots under  350 yards, once you select a cartridge and bullet type you like, pick the heaviest bullet your gun will shoot well and go with that.

[high country]

rob, there is a tangent you need to consider. look at penetration depths vs velocity. often higher velocity equals lower penetration due to bullet upset.....hence my "right bullet for your velocity window". FWIW a 100gr .257 made a full pass through breaking the off side shoulder on a 300 plus yard poke.
 
many people want to have a huge enrgy number, and while it is not a bad thing, it is largely unnecessary. it just does not take 1000 ft/lbs to push a .308" hole through a critter. I am not advocating hunting elephants with bb guns, but I have had the fortune of taking and seeing many animals killed. I always laugh at the minimum required to do the job guys. I have seen a bang flop from a 308win at a distance that nobody would believe.....heck, I would not have believed it with out seeing it.

[Rob]

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.

[Rob]

rob, there is a tangent you need to consider. look at penetration depths vs velocity. often higher velocity equals lower penetration due to bullet upset.....hence my "right bullet for your velocity window". FWIW a 100gr .257 made a full pass through breaking the off side shoulder on a 300 plus yard poke.
 
many people want to have a huge enrgy number, and while it is not a bad thing, it is largely unnecessary. it just does not take 1000 ft/lbs to push a .308" hole through a critter. I am not advocating hunting elephants with bb guns, but I have had the fortune of taking and seeing many animals killed. I always laugh at the minimum required to do the job guys. I have seen a bang flop from a 308win at a distance that nobody would believe.....heck, I would not have believed it with out seeing it.

That is EXACTLY the point I was trying to make, thanks for doing it in far less words!  this is where Momentum comes into play.  Momentum and Sectional density are the #'s to look at to measure penetration.  Velocity has little to do with it IMO.  I'll cross post an example in a moment. 

[Rob]

Here is a post from my Africa thread.  it shows stats on three different bullets of differing caliber and weights, but identicle ME's.

So I am re-reading “the perfect Shot” by Kevin Doctari
https://www.safaripress.com/product.php?productid=434&cat=0&page=1

The first 40 or so pages offers some of the best reading I have come across in terms of layman level discussion of ballistics as they pertain to hunting large game.

I am sure that what follows is a penetrating insight into the obvious for everyone else, but it clarified some things for me so I thought I’d share.

With Large game, especially African game, penetration is king.  You want a bullet that you know will go through thick hides, heavy bones, and still reach the boiler room.  I know I often look at energy when trying to compare different bullets for different applications-I have always known that this was not the best gauge, but I have not known why, nor have I known what other stats to use to help make such a decision.  In the book, Kevin made the statement that Muzzle energy means very little when it comes to making such a decision and then provided some interesting insights.

When selecting a cartridge, he looks at three variables:
•   Muzzle energy
•   Sectional Density
•   Momentum
To calculate these variables he uses Caliber, bullet weight and velocity

To illustrate his point, he did an interesting compare.  (I am not using his #’s as I don’t have his book here in front of me, although I do have all his formulas used to calculate the #’s.)  He took three cartridges in typical bullet weights and plugged in velocities such that all the bullets had similar muzzle energy.  The rifles he used were a 30.06 Springfield, a 375 HH and a fictitious gun he called the 22 LR “super”.   Here are the stats:

22 LR Super (again, this is a fake gun for illustrative purposes)
•   40 grain bullet, .224 caliber, traveling 6,600 FPS.

30.06 Springfield
•   220 grain bullet, .308 caliber, traveling 2,800 FPS

375 HH
•   300 grain bullet, .375 Caliber, traveling 2400 FPS.

These velocity/bullet weight combos yielded very similar Muzzle energy #’s:
•   22 LR Super 3,870 Ft/lbs
•   30.06 3,831 Ft/lbs
•   375 HH 3,838 Ft/Lbs

The question is, what would you rather shoot a charging Cape Buff with to get max penetration?  I jump right to the 375 HH, but why?  If I look at Muzzle energy alone, the answer would be, they are all the same. 

Kevin next calculated Momentum and Sectional density.
•   Sectional Density = Bullet Weight in Lbs/(Caliber squared)
      o         Sample:  for 30.06 SD= ((220/7000)/(.308*.308)) = .331
•   Momentum = (Bullet Weight * Velocity)/7000 Note:  the 7000 is to convert grains to pounds
      o         Sample for 30.06 = (220*2800)/7000 = 88.0

                             30.06   375 HH   .22 LR Super
Bullet Weight                220   300   40
Caliber                        0.308   0.375   0.224
Velocity                       2800   2400   6600
             
Sectional Density                0.331   0.305   0.114
Muzzle Energy (ft/lbs)   3831   3838   3870
Momentum Value (lb/FPS)   88.0   102.9   37.7

(The larger the momentum and Sectional Density #’s, the better the penetration.)

Now we are getting into how I am interpreting these #’s so I may be off. 

I am assuming the following:
•   Must be for Solids as I would assume penetration would be reduced for a bullet that expands
•   Must assume that the bullet retains 100% of its weight
•   Assumes penetration begins at the muzzle – one would need to lower the Velocity #’s to the down range distance that penetration begins.

So if I read this correctly, even though the SD on the 30.06 is the best (~9% greater than the 375 HH) and the Muz energy is about equal, the 375 HH shooting a heavier bullet at a slower speed will provide better penetration due to a momentum value that is 14% greater.  (i.e. it is harder to stop so it goes further). 

Oh yeah, and the “super” 22LR has pathetic penetration performance in spite of roughly equal muzzle energy, so it is “right out”

So my question would be, if the momentum value is greater for the 375 HH by 14%, does that mean that it will penetrate 14% deeper?  I’d love to see a table that translates a momentum value into inches of penetration in ballistics gel.

By the way, when looking at the 300 WM vs 338 WM, the 338 WM comes out on top.  I fudged the #’s such that the muzzle energy was roughly = between the two for an apples to apples compare.
                                  300 Win Mag    338 WM
Bullet Weight                        180        225
Caliber                              0.308        0.338
Velocity                              2950        2600
         
Sectional Density                 0.271      0.281
Muzzle Energy (ft/lbs)          3479       3378
Momentum Value (lb/FPS)     75.9        83.6

Anyway, I found this an interesting way to get hard #’s that back up what we have been saying on this topic. 
 

[high country]

pretty good read, now before everyone runs out and grabs a super magnum, remember it is very easy to overdrive a bullet. shove a berger fast and hit something hard.....its not good. would a barnes do better? I myself have taken elk with the smk/berger and if a good braodside shot opportunity arises, it has amazing results as it explodes violently about the time it gets to the good stuff.....add a bit of space between impact and the good stuff and results can change quickly.