Ballistics school

mackillan

mackillan

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I have some questions about ballistics. What are the factors involved in accuracy, recoil, and killing power?

1) bullet mass
2)velocity
3) sleekness of bullet (longer bullet will carry same grains of bullet more accurately)

Can someone give me a lesson on this.

I am also wondering if the number of grains of bullets can impact on the kick. I am also wondering if a 300 win mag in 150 grains would kick less than the 180 and still take out a moose. Ive always shot a 30-06 180 grain with moose and it never failed me with moose but I traded it in with a scope for a 300 win mag and the mag is obnoxious at the range.
 
Large books have been written about ballistics, but here's a Coles Notes version. The quality of the bullet is paramount to accuracy, and the bullet's center of gravity must match it's dimensional center. The rate of spin given to the bullet must be appropriate to the bullets length.

Velocity has little to do with accuracy in that very slow and very fast bullets can be very accurate. Velocity combined with the structure of the bullet can have a significant impact in the size of the wound channel.

Killing power relates to the amount of tissue that can be destroyed by the passage of the bullet. The frontal area of the bullet combined with the length of penetration determines the wound volume. The greater the wound volume, the faster the animal is deprived of oxygen to the brain resulting in death.

Recoil is effected by the weight of the bullet, the weight of the powder charge, the resulting velocity, and the weight of the gun in which the cartridge is fired.
 
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Your first three questions are far too general and the answers could fill a book or two. Do some reading on the subject.
Regarding the kick of your .300..... kick is related to stock shape, rifle mass, and the ammunition used. If only looking at the ammo, kick can be reduced by reducing the total amount of "ejecta" - both bullet and burnt powder, and by reducing the speed. You can turn your .300 mag into a 30-06 by using "reduced recoil" factory loads or hand loading a lesser amount of a faster burning powder with a light bullet.
Yes, a 150 grain .30 caliber bullet can kill a moose, but he only ones I would consider from a full loaded .300 are premiums like the Nosler partition or Barnes X. A full loaded and lightly constructed 150 grain bullet shot from a .300 may not penetrate well enough for clean kills of big critters. With conventional bullets the .300's perform best with 180 or 200 grain bullets on moose. I'm sure others will have differing opinions.
Too bad you sold your 30-06. It was a nearly ideal moose rifle, more is not always better for many folks.
 
quote: "3) sleekness of bullet (longer bullet will carry same grains of bullet more accurately)"


Boomer, in the first reponse hits on this when he states the twist must match the length of bullet. For an extreme example a proper twist will stabilise even a round ball. Where your statement may have an application may be when shooting a rifle with a twist for say 200 gr bullets then a long 165 may be better than a stubby one. Not because of any magic but because it more clossely matches the particular twist of that rifle.
 
Then, would a particular caliber have optimal sizes eg grains in terms of accuracy?
Boomer said:
Large books have been written about ballistics, but here's a Coles Notes version. The quality of the bullet is paramount to accuracy, and the bullet's center of gravity must match it's dimensional center. The rate of spin given to the bullet must be appropriate to the bullets length.

Velocity has little to do with accuracy in that very slow and very fast bullets can be very accurate. Velocity combined with the structure of the bullet can have a significant impact in the size of the wound channel.

Killing power relates to the amount of tissue that can be destroyed by the passage of the bullet. The frontal area of the bullet combined with the length of penetration determines the wound volume. The greater the wound volume, the faster the animal is deprived of oxygen to the brain resulting in death.

Recoil is effected by the weight of the bullet, the weight of the powder charge, the resulting velocity, and the weight of the gun in which the cartridge is fired.
Click to expand...
 
oh my.... where to start.

Ok there are many factors here, and you missed the rate of twist required to stablize a bullet. Bullet shape will play a big roll in longer range shooting, ie boattails, but then they are longer then the same weight flatbase bullets and require a faster twist. But rifles will shoot a range of different bullet weights.

take for instance the 223, (or any .22 cal) with a 1 in 12 you limited to the lighter bullets say less then 60 grn but with a faster 1 in 9 you good to go with the heavier bullets.

Now easiest for you since you have had good results with your 30-06 would be to just load your 300WM with 180grn bullets and be happy. However bullet construction is going to come into play as the 300WM is faster and some people think that ordinary bullets will fail to expand properly at these higher speeds and you need preimum bullets.

Me personaly I use 200grn Nosler Accubonds in my 300WM for moose, works good for me so far. Last years moose was about 300m, no problems.


Oh and for more information you may want to visit the reloading section here on CGN lots of good information and opinions ;) there
 
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mackillan said:
Would not a bullet with more velocity have a flatter trajectory on the basis of getting out there faster before gravity can act on it?
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Yes, but...

The greater the velocity the farther the bullet gets before the effect of gravity makes the trajectory drop steeply, but ultimately the trajectory always drops to the same level, i.e. all the way to the ground, and at some point the steepness of that drop increases sharply.

So, the longer the trajectory remains relatively flat, the easier it is for the shooter to choose a correct point of aim over longer ranges, but a bullet with a less flat trajectory may be just as accurate. Accuracy is a matter of consistency, that the bullets fired keep hitting the same spot if fired at the same point of aim so long as various other factors don't change between shots. How the actual bullet can affect that consistency is determined by whether the design of the bullet is appropriate to the cartridge and the gun, and whether the quality of materials and methods of manufacture produce bullets minimise variations in shape and mass and the distribution of weight from bullet to bullet as they come off the production line. It is a matter of the shooter knowing how to use the accuracy of that bullet.
 
Isnt accuracy to some extent about judging distance in the field and there would less chance of needing more judgement with a flatter trajectory? If traj was no issue and we could all judge distance perfectly and memorized our trajectory and had puters in our head wouldnt we be well enough ahead with 30-30s?
TheTooner said:
Yes, but...

The greater the velocity the farther the bullet gets before the effect of gravity makes the trajectory drop steeply, but ultimately the trajectory always drops to the same level, i.e. all the way to the ground, and at some point the steepness of that drop increases sharply.

So, the longer the trajectory remains relatively flat, the easier it is for the shooter to choose a correct point of aim over longer ranges, but a bullet with a less flat trajectory may be just as accurate. Accuracy is a matter of consistency, that the bullets fired keep hitting the same spot if fired at the same point of aim so long as various other factors don't change between shots. How the actual bullet can affect that consistency is determined by whether the design of the bullet is appropriate to the cartridge and the gun, and whether the quality of materials and methods of manufacture produce bullets minimise variations in shape and mass and the distribution of weight from bullet to bullet as they come off the production line. It is a matter of the shooter knowing how to use the accuracy of that bullet.
Click to expand...
 
Then, would a particular caliber have optimal sizes eg grains in terms of accuracy?
Click to expand...

If a bullet is too long to be stabilized by the rifling,it won't be accurate,and could even tumble.Then again a solid copper bullet will normally be longer than a lead core bullet of the same caliber and weight,so the optimal weight may vary with the bullet construction.
 
mackillan said:
Isnt accuracy to some extent about judging distance in the field and there would less chance of needing more judgement with a flatter trajectory? If traj was no issue and we could all judge distance perfectly and memorized our trajectory and had puters in our head wouldnt we be well enough ahead with 30-30s?
Click to expand...


You asked about the accuracy of bullets. Bullets don't know their own trajectory and they don't select the point of aim. That part of accuracy comes from the shooter, regardless of the velocity and trajectory.

If you can judge distance perfectly and know the trajectory of the load you are using, you can be just as accurate with a 30-30 as you can with a 22-250. Raising the point of aim at a given range too much for the trajectory of a higher velocity "flat shooting" round will reduce your accuracy, just as not raising it enough will cause a miss with a lower velocity round.
 
mackillan said:
Would not a bullet with more velocity have a flatter trajectory on the basis of getting out there faster before gravity can act on it?
Click to expand...

Nope! Gravity is constant on all objects. If you were to shoot a bullet from a barrel that was parallel to the ground and drop the same bullet from the same height at the same time both would hit the ground at the same time.
 
Hang on - Agreed, gravity is constant.
However, a faster bullet will reach the target in less time, therefore less time for gravity to accelerate the bullet downward, hence less drop.
 
Exactly. A bullet that has a high velocity bullet would reach out farther as it hits the ground as the same time as a slower blllet. I didnt word it correct.
Omega said:
Nope! Gravity is constant on all objects. If you were to shoot a bullet from a barrel that was parallel to the ground and drop the same bullet from the same height at the same time both would hit the ground at the same time.
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Having a flatter trajectory is useful for accuracy for some people in the field as it lessens the impact of one variable upon accuracy. One cant totally judge for accuracy in the field hence a flatter trajectory uis useful. If a bullet had a flat trajectory to infinity it would be, for most shooters, more accurate in the field.
TheTooner said:
You asked about the accuracy of bullets. Bullets don't know their own trajectory and they don't select the point of aim. That part of accuracy comes from the shooter, regardless of the velocity and trajectory.

If you can judge distance perfectly and know the trajectory of the load you are using, you can be just as accurate with a 30-30 as you can with a 22-250. Raising the point of aim at a given range too much for the trajectory of a higher velocity "flat shooting" round will reduce your accuracy, just as not raising it enough will cause a miss with a lower velocity round.
Click to expand...
 
mackillan said:
If a bullet had a flat trajectory to infinity it would be, for most shooters, more accurate in the field.
Click to expand...


Not really.

Vertical drop is one very small part of accurate shooting. These days anyone with a few bucks can buy a decent rangefinder and an afternoon at the range will provide all the "real-world" hard data about what your particular rifle/cartridge/bullet combination can do.

Shooter ability - and that relates to actual experience and trigger time - is very-very important. Even a rifle that shoots bug holes off a rest can have a new or poor shooter printing 2 or 3 inch groups at 100 yards from field positions. While this is perfectly fine at 100 yards or so those same groups open up to 8-12 inches at 400 yards which is usually enough wound or miss an animal.

Add wind to the "operator error" I just mentioned and all bets are off. At 400 yards the wind may push your bullet 5 -10 inches or more to the left or right. Add in the 12" shooter ability and a bit of buck fever and it becomes obvious even a good sized wood shed may be too small a target at a quarter of a mile.
 
Range finder in the field?? Wind guage? Computerized prinout of how high to shoot. Man there isnt the time. I cant belive that people would claim that flat shooting isnt important to accuracy in the field.
'Boo said:
Not really.

Vertical drop is one very small part of accurate shooting. These days anyone with a few bucks can buy a decent rangefinder and an afternoon at the range will provide all the "real-world" hard data about what your particular rifle/cartridge/bullet combination can do.

Shooter ability - and that relates to actual experience and trigger time - is very-very important. Even a rifle that shoots bug holes off a rest can have a new or poor shooter printing 2 or 3 inch groups at 100 yards from field positions. While this is perfectly fine at 100 yards or so those same groups open up to 8-12 inches at 400 yards which is usually enough wound or miss an animal.

Add wind to the "operator error" I just mentioned and all bets are off. At 400 yards the wind may push your bullet 5 -10 inches or more to the left or right. Add in the 12" shooter ability and a bit of buck fever and it becomes obvious even a good sized wood shed may be too small a target at a quarter of a mile.
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