Heavy Bullets!

[Broz]

Bryan Litz commented (in an older thread I couldn't find) on the higher BC lower weight mono bullets and said that they won't actually fly the same as a higher weight bullet of the same BC (assuming the bullets are the same caliber).

The way it was explained to me is to think of wiffle ball and a baseball of the same size and shape (identical BC so to speak) and throw them both as hard as you can. The wiffle ball will start out much faster but it loses its velocity at a quicker rate because it doesn't have enough weight to maintain its momentum. This extreme loss of momentum in the wiffle ball allows the baseball (heavier) to carry its momentum further and deflect less in the wind.

Browninglover, Thank you for the analogy. It helps to explain what and why the test results are what they are. All I know is what I have seen and what works for me.

Thanks
Jeff

 

[Long Time Long Ranger]

The ballistic coefficient equations take into account the ratios between weight and bullet design. The same BC is the same BC. A bullet with a lower bc will at some point in space be overtaken by the higher bc bullet no matter what the weight of the two bullets are. Very simple. The weight is not an issue. Just look at the bc and the bc/velocity ratios to see what has the best ballistics out to a given range where you intend to be shooting.

 

[Broz]

I guess that answers my question then, you have not done any actual field testing? I think I will take Bryans and the others word for it since their findings mirror mine. That is very simple.

Thanks

Jeff

 

[Scot E]

Good Thread. A couple things of interest to me.

A ballistic program will show the same drop and drift exactly with 2 bullets with the same BC but different weights. So the question is does real world data differ from this. In my experience the answer is no, at least not out to 900 yards or less and if it does differ it is very minor. I do, with some loads, begin to see some changes beyond 1000 but they are very small in most cases. But I don't shoot must past 1000-1200 yards and I do know that beyond those distances ballistic programs do need more tweaking to stay with real world results.

But this isn't really the issue in my mind because the real question should be when do heavier bullets shot at lower velocities overtake lighter bullets shot at higher velocities in drop and drift categories.

BC is important but you can't ignore velocity either because it is directly related to time of flight (TOF) which must affect bullet flight when dealing with the affects the wind and gravity. It is easy to prove with a ballistic program or shooting in the field that shooting bullets at faster velocities means less drop and drift. So the only question is where the line is drawn where shooting a faster bullet with a lower BC is overtaken by a bullet being shot slower but with a higher BC.

The point I would drive home is that the answer to what is the better method will be different for everyone. As you can see here in this thread some of the ELR guys find the heavy weights to be a really big advantage and rightfully so because at ELR a heavier higher BC bullet will always perform better. But for guys like me, and 95% of LR shooters, we need to do our home work and find out where a lighter but faster bullet breaks even with a heavier one. If we only shoot below that distance then at least for me it will be the lighter bullet I choose because I will get less recoil which gives most guys a bit more accuracy and will allow me to shoot a lighter carry weight gun a bit better. And in most cases I will get less drop and drift as well. Plus a higher velocity bullet is important in some circumstances when guys are using bullets that require a certain FPS to open up properly. In addition, for the hunting situations when a faster shot is needed it is nice, at least for me, to have the flattest shooting bullet I can get. Then I can quickly hold over with my reticle and still know I am going to dump him where he stands. Yes, for the longer range stuff I do take my time and make sure I have everything in line before making a shot.

To summarize I think there are merits to both concepts but one has to know their max range and test to that distance to find out what is best.

Scot E.

 

[angus-5024]

Numbers dont lie, without human error anyway.

If you have a lead ball with a weight of 25 lbs, you also have an aluminum ball weighing 2 lbs; these balls are the exact same shape. They are dropped from a building at the same time. The balls will hit the ground at the same time, cant argue it. learned it in grade 6 or 7. pretty elementry. The same goes for if those same balls are launched horizontal, they will actually strike the ground at the exact same time as the balls that were dropped. The only thing that can change that is external forces (wind, air density...). Thats where haveing more velocity is a ++ because you can cover more ground in the time it takes to hit the ground

With wind being the main external force we're concerned about, lets break it down. Mass helps to boost B.C, but its not B.C.

The Two balls again. If a force of X is applied to the heavy ball, It will be accelerated in the direction of force. Acceleration= Force(net)/mass.
If the light ball has the same amount of force applied to it, useing the above formula, its obvious that it will be moved more.

So we can saflely say that two objects of identical shape will fall at the same rate, but when a force is applied to them (wind), the lighter one will be affected more.

The catch is that two bullets having the same b.c, one being heavier, will not have the same shape. The heavier bullet has the momentum advantage, being able to use that momentum to "plow" through its medium (air). However, that advantage could be offset by velocity for awhile, but eventually the heavier bullet will catch up.

typically the heavier bullets will have less surface area, which is where I think that it make the biggest diffrence, becuase less force is applied to the bullet with less area.

Velocity can offset that surface area however, because Time of Flight is less. That means less time for the bullet to be acted upon. It just get there faster.


All that being said, I think that the ballistics calulator doesnt lie.

Drift 1k Drop 1k TOF 1k
300 grain .76 B.C- 4.5moa- 25.8moa- 1.36sec
mv 2750

262 grain- .76 B.C- 3.8moa- 19.6moa- 1.193sec
mv 3100

Numbers dont lie, but feild data cant be ignored either. Im gonna see if I can ring this out further with feild tests, but I suspect that at 1 k the ligher bullet wins.

At ELR Im thinking that the heavies are gonna take the cake every time.



I just want to thank both Broz and LTLR for there insight into this. Two very knowledgeable shooters who have more than theory behind them. Thanks for your time guys!

 

[Browninglover1]

The ballistic coefficient equations take into account the ratios between weight and bullet design. The same BC is the same BC. A bullet with a lower bc will at some point in space be overtaken by the higher bc bullet no matter what the weight of the two bullets are. Very simple. The weight is not an issue. Just look at the bc and the bc/velocity ratios to see what has the best ballistics out to a given range where you intend to be shooting.

I'm not being a jerk when I ask this, but do you have an article I could read that talks about how BC's are computed? I remember reading an article in Shooting Times many years ago that said BC's are calculated off of the G1 drag model that only takes into account a bullets shape. The problem with the low drag bullets is that they are so far removed from the standard G1 model that results can be drastically different depending on what velocity you are shooting the bullets at. That is supposedly the reason that the G7 standard was developed because it computes a number based of a model that much closer resembles the actual low drag bullets.

Again, I don't want to sound like a jerk but I would really like to understand. Like I said, I understood that BC's were computed off the "drag factor" determined by bullet shape and had nothing to do with weight, but I could definitely be wrong.

 

[Broz]

Scott, I hear what you are saying but lets not forget the OP article was done at only 1000 yards and supported this. This was preformed by two respected long range competative shooters. I agree it becomes more prevelant at longer distances (everything does) and the shortest I did the test was 1000 yards. I ask no one to take my word for it. I would suggest if the article is not sufficent proof then by all means get with a buddy and do the test for your self. You may be surprised.

As far are the programs windage info being correct? That is hard to tell as we perfect the drops( elevation) with BC and velocity tweeking to get them perfect. Again elevation is something we can get spot on. But windage / wind drift is not as we have no way I know of to prove what actual winds the bullet is actually traveling in. So with what I have to work with I can't call a program right or wrong. But, like I have done, we can prove which bullet does indeed have the most drift simply by shooting them back to back in like conditions. And the more samples the better.

One thing this has proven to me is to look at what is in front of you. Not what someone says. The small fast bullet coolaid does not taste good to me. Now a heavy fast bullet,... well that has a very appealing flavor. I have some of that brewing as we speak.

Jeff

 

[Browninglover1]

I just want to thank both Broz and LTLR for there insight into this. Two very knowledgeable shooters who have more than theory behind them. Thanks for your time guys!

Ditto Angus' remarks. As a side remark to what you said, the numbers in a ballistics calculator are only as good as the equations themselves and the variable inputs. I haven't played with a lot of ballistics calculators, but when comparing 3 or 4 different calculators I often come up with different values (often within .2 MOA but different nonetheless) which tells me that each calculator is probably using a different version of a general equation.

I also agree, that at normal ranges (for me less than 600 yards) the lighter faster bullets seem to be easier for me to make hits with, but as I extend the range past 600 the heavies seem to make it easier for me. I have not done enough real shooting beyond 600 though to have enough data to support what I feel but I do feel the heavy bullets make the longer shots easier.

 

[Broz]

So we can saflely say that two objects of identical shape will fall at the same rate, but when a force is applied to them (wind), the lighter one will be affected more.

The catch is that two bullets having the same b.c, one being heavier, will not have the same shape. The heavier bullet has the momentum advantage, being able to use that momentum to "plow" through its medium (air). However, that advantage could be offset by velocity for awhile, but eventually the heavier bullet will catch up.

I think this is well stated and brings one important thing to the discussion. We do input BC, bullet length , weight, diameter into a program for a correction and to model the drag. But I feel actual shape has something to do with all this too and is sometimes over looked. We all like to think the sleekest looking bullet is best. But is it? This is why I say test them. The proof is in the pudding. What ever the reason is. Hits closer to the point of aim is what I seek.

Jeff

 

[WildRose]

On a ballistics computer enter data for two bullets with identical ballistic coefficients. One bullet at 150 grains and the other at 300 grains weight. With weight being the only change in the data. See what the results are. The two will probably be identical no matter the weight entered.

I don't think I forgot any important factors in the equation. The same bc should fly the same. The key is finding the best velocity/BC combination with adequate weight/construction to do the job. A heavier bullet will not drift less just because it is heavier.

I'm going to have to disagree with you as well on this point.

The heavier an object is, the more force it takes to cause a deviation in it's flight path.

Thus when you compare two bullets of any given caliber of the same design traveling at similar velocities, the drift of the heavier bullet is going to be less with the same wind velocity and range.

What little tinkering I've done also shows that with different calibers comparing bullets of the same design shows the same thing unless you are running the heavier bullet at a much, much slower velocity which then allows for dramatically increased flight time which then allows the same wind to act on it for a much longer period of time than the faster smaller bullet.

 

[WildRose]

Browninglover, Thank you for the analogy. It helps to explain what and why the test results are what they are. All I know is what I have seen and what works for me.

Thanks
Jeff

I don't think that problem is as severe as it used to be. When for example the first bans on lead shot came out we quickly discovered that Steel just didn't cut the mustard because it was less dense than Lead.

Similarly with the early monometal bullets it didn't matter how the bullet looked you just couldn't get the same density in the same sized projectile as you could with traditional bullets.

When we look today at the SD's of the modern monometal bullets they are indeed much, much better but they still just don't seem to fly quite as well as the lead/copper jacketed bullets.

One problem we get into in these discussions is that the average shooter cannot shoot well enough to do a true side by side comparison because they either lack the skill or the equipment for true precision no matter what they are shooting.

It's a very, very small percentage of shooters that have both the skill and equipment to really judge the differences in bullet performance especially at long range.

We are really fortunate here to have quite a few people who contribute to this site that have both which makes it a great resource.

 

[WildRose]

I'm not being a jerk when I ask this, but do you have an article I could read that talks about how BC's are computed? I remember reading an article in Shooting Times many years ago that said BC's are calculated off of the G1 drag model that only takes into account a bullets shape. The problem with the low drag bullets is that they are so far removed from the standard G1 model that results can be drastically different depending on what velocity you are shooting the bullets at. That is supposedly the reason that the G7 standard was developed because it computes a number based of a model that much closer resembles the actual low drag bullets.

Again, I don't want to sound like a jerk but I would really like to understand. Like I said, I understood that BC's were computed off the "drag factor" determined by bullet shape and had nothing to do with weight, but I could definitely be wrong.

BC's are calculated in different ways.

Hornady's 8th edition reloading manual has a couple of chapters that explain in some detail ballistics including how BC's are computed.

There are two basic ways.

Once is Drag of a standard projectile divided by drag of test projectile.

The other is more complex where you have:

BC= WID2 (D squared) where
W=mass in lbs.
I=coefficent of form factor
D=Bullet Diameter (measured in inches).

In short both methods tell you how efficiently a bullet will fly at a given velocity.

BC's are not however static as they change as velocity changes.

Bullets that fly the most efficiently at high velocity tend to destabilize when transitioning from Supersonic to Subsonic speeds.

Bullets designed for subsonic stability will not fly well at all at supersonic velocities.

Think about a Piper Cub and the SR-71. The cub flies great and is extremely manueverable at low speeds, but would tear itself apart if you you pushed it beyond Mach 1.

The SR71 flies at Mach2 plus extremely efficiently but cannot fly at all at low speed.

Calculated BC's are very helpful in picking bullets, but the highest BC will not always be the best bullet for every application.

 

[Bullet bumper]

The G1 model bullet weighs 1 pound ( 7000 grains ) and has a BC of 1.
So if a bullet has a BC of .5 it flys with 50% of the efficiency of the G1 bullet.
So if weight is the most important factor in a bullets performance with a .5 BC it should weigh 50% of the G1 bullet , 3500 grains ????
However there is a few .5 BC bullets out there that only weight upto 400 to 500 grains , that is only about 15% of half the weight of the G1 bullet ???
So is weight the most important factor ?? I am not saying this is right . I am just saying that it seems queer to me.
I do the ballistic calculations and the heavy ( longer ) bullet seems to exhibit the least amount of windage .

 

[WildRose]

The G1 model bullet weighs 1 pound ( 7000 grains ) and has a BC of 1.
So if a bullet has a BC of .5 it flys with 50% of the efficiency of the G1 bullet.
So if weight is the most important factor in a bullets performance with a .5 BC it should weigh 50% of the G1 bullet , 3500 grains ????
However there is a few .5 BC bullets out there that only weight upto 400 to 500 grains , that is only about 15% of half the weight of the G1 bullet ???
So is weight the most important factor ?? I am not saying this is right . I am just saying that it seems queer to me.
I do the ballistic calculations and the heavy ( longer ) bullet seems to exhibit the least amount of windage .

Weight is but one of the factors in the equation, but when it comes to resisting cross winds it's extremely important.

The heavier the object in flight is, the more energy it takes to force it from it's initial flight path.

The amount of force exerted against that bullet is a function of wind direction, speed, and duration of time of flight.

The profile of the bullet also comes into play as a long, streamlined bullet presents less surface area for the wind to work against than a big fat flat or round nosed bullet.