Could someone explain this to me more fully? I'm beginning to realize that a bullet that shoots flat and accurately out to 100 yards may fail miserably at longer ranges. I've been shooting 140 grain, semi-boat tail in 270. What would fly better at say 700 yards. Pardon my ignorance on all this.
- Thread starter Steve1
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BC is a measurement of drag of a bullet. The higher the BC the less drag. Originally, the BC model was based on flat point and flat base style bullets. Now that model is the basis for G1 BC while a newer model, based on the sleeker designs today, is the G7 BC. BC won't really make any difference at normal hunting distances but it will at 700 yards. Sometimes a lot. If you want bullets that hold up better at longer ranges for your 270 then look at various makers and choose a higher BC bullet.
Now for the hard part. Having a good shooting 700 yard load is not about BC. It is about your overall load.
Now for the hard part. Having a good shooting 700 yard load is not about BC. It is about your overall load.
In a nutshell, ballistic coefficient is a tool for calculating the rate of decay of the velocity of a bullet in flight. How quickly does the drag of air slow it down?
That knowledge is important to shooters because we'd like to be able to use a theoretical tool to determine how much hold-over we need to shoot at a target at any given range as opposed to having to shoot a whole bunch of bullets at increasing ranges in 1-yard increments to figure it out.
How high you need to aim above the target at any given range is determined by how far the bullet will fall in flight.
How far the bullet will fall in flight is a function of acceleration due to gravity, which is constant, and the time of flight.
If you know how fast the bullet was traveling when it left the muzzle, and you know the rate at which its velocity will decay, you can calculate how long it will take to reach any given range. ToF lets you calculate drop and knowing drop lets you calculate hold-over.
That knowledge is important to shooters because we'd like to be able to use a theoretical tool to determine how much hold-over we need to shoot at a target at any given range as opposed to having to shoot a whole bunch of bullets at increasing ranges in 1-yard increments to figure it out.
How high you need to aim above the target at any given range is determined by how far the bullet will fall in flight.
How far the bullet will fall in flight is a function of acceleration due to gravity, which is constant, and the time of flight.
If you know how fast the bullet was traveling when it left the muzzle, and you know the rate at which its velocity will decay, you can calculate how long it will take to reach any given range. ToF lets you calculate drop and knowing drop lets you calculate hold-over.
I thought I'd throw out some more stupid questions. Is the ballistic coeficiant for a bullet listed somewhere? I imagine you can tell just by looking at a bullet. Long, sleek, boat tails, would probably fly the best.
In the past I've always looked for that optimum weight bullet, that drops the least at longer ranges. I'm wondering though if that all goes out the window if you are shooting beyond 500 yards. Would a guy be better off with a heavier bullet.
I'm not sure if 130 grain or 140 grain bullets are flatter shooting, in 270. I think they are about the same. They both fly flatter than the lighter or heavier bullets out to 500 yards. I'm just wondering out beyond that range. Would a heavier more stream lined bullet be better.
I really don't plan to shoot at big game beyond 500 yards, but I don't think I'd hesitate to shoot at a wolf, way out there. I hate those critters....
In the past I've always looked for that optimum weight bullet, that drops the least at longer ranges. I'm wondering though if that all goes out the window if you are shooting beyond 500 yards. Would a guy be better off with a heavier bullet.
I'm not sure if 130 grain or 140 grain bullets are flatter shooting, in 270. I think they are about the same. They both fly flatter than the lighter or heavier bullets out to 500 yards. I'm just wondering out beyond that range. Would a heavier more stream lined bullet be better.
I really don't plan to shoot at big game beyond 500 yards, but I don't think I'd hesitate to shoot at a wolf, way out there. I hate those critters....
The BC is listed in every reloading book I have seen for each bullet listed.
More or less, heavier bullets have higher BC's because of energy generated.
Yes, all long range shooters use the heaviest, most pointed boat tail bullet their rifle will shoot accurately.
I am using generalities here but Brian Litz's book contains the most complete information I have every read on this subject.
More or less, heavier bullets have higher BC's because of energy generated.
Yes, all long range shooters use the heaviest, most pointed boat tail bullet their rifle will shoot accurately.
I am using generalities here but Brian Litz's book contains the most complete information I have every read on this subject.
Some great responses above - but I'll add my 2 cents. In order to calcualte a bullets trajectory (via a ballistics program) the variables are: Bullet weight/diamater, speed, BC. With that you can determine how "flat" it may be.
Within the same caliber, there is a classic trade-off between lighter bullets with lower BC's that can be driven faster, vs heavier bullets with higher BC going slower.
EDIT: Given the same shape and caliber, longer (and thus heavier) bullets tend to have higher BC's.
Long range shooters tend to favor higher BC/slower model as the higher retained energy at distance has advantages.
This is a great place to experiment with bullet/speed combinations and has most bullets listed.
JBM - Calculations - Trajectory (Simplified)
Yes, there are 2 distince BC models out there now (G1 and G7) so be sure you know which one you are looking at and be sure to use the same one when making bullet to bullet comparasions.
I shoot a 270 WSM for hunting and I'm using the 140 grain accu-bond at about 3150 fps.
Within the same caliber, there is a classic trade-off between lighter bullets with lower BC's that can be driven faster, vs heavier bullets with higher BC going slower.
EDIT: Given the same shape and caliber, longer (and thus heavier) bullets tend to have higher BC's.
Long range shooters tend to favor higher BC/slower model as the higher retained energy at distance has advantages.
This is a great place to experiment with bullet/speed combinations and has most bullets listed.
JBM - Calculations - Trajectory (Simplified)
Yes, there are 2 distince BC models out there now (G1 and G7) so be sure you know which one you are looking at and be sure to use the same one when making bullet to bullet comparasions.
I shoot a 270 WSM for hunting and I'm using the 140 grain accu-bond at about 3150 fps.
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Steve,
Taking a quick look at Berger Bullets 270 caliber hunting bullet offerings you will see the G1 and G7 BC listed. BUT, and I like that Berger does this, you will also see the minimum twist rate your barrel needs to fully stabilize each of those offerings. It is interesting to note that their highest BC 130 grain bullet takes a faster twist barrel to stabilize. That is due to overall bullet shape (length). So, in order to get the most accuracy from any bullet it has to be matched to the right components to make good things happen.
Also, a little use of the Google Fu will reward you with a lot of info on BC, Twist rates and other wonders of physics involved in this little game or shooting. Good Luck!
Taking a quick look at Berger Bullets 270 caliber hunting bullet offerings you will see the G1 and G7 BC listed. BUT, and I like that Berger does this, you will also see the minimum twist rate your barrel needs to fully stabilize each of those offerings. It is interesting to note that their highest BC 130 grain bullet takes a faster twist barrel to stabilize. That is due to overall bullet shape (length). So, in order to get the most accuracy from any bullet it has to be matched to the right components to make good things happen.
Also, a little use of the Google Fu will reward you with a lot of info on BC, Twist rates and other wonders of physics involved in this little game or shooting. Good Luck!
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I shoot a 270 WSM for hunting and I'm using the 140 grain accu-bond at about 3150 fps.[/QUOTE]
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Djskit,
I've been shooting 140 grain accu-bonds too. I love their accuracy. I wonder how they would perform at beyond 500 yards. I've killed one elk with them and a deer or two. They seem to hold together well. I recently shot a four shot, 1/4 inch group with them, at 100 yards, so I hoped to keep shooting that load.
I shoot a 270 WSM for hunting and I'm using the 140 grain accu-bond at about 3150 fps.[/QUOTE]
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Djskit,
I've been shooting 140 grain accu-bonds too. I love their accuracy. I wonder how they would perform at beyond 500 yards. I've killed one elk with them and a deer or two. They seem to hold together well. I recently shot a four shot, 1/4 inch group with them, at 100 yards, so I hoped to keep shooting that load.
So, it sounds like I need to shoot the longest heaviest bullets that my rifle will stabilize accurately for the flattest trajectory at beyond 500 yards.
Does that mean I need to shoot 220 grain bullets out of my 300 Winchester? I'm not sure if my shoulder will take that. I always figured they would drop way too much at longer ranges, but maybe I am wrong. I guess I need to get out there and do some more experimenting. I have a range that I can shoot at about 700 yards. I appreciate your advice and help on this. It would take a lifetime to learn all this on your own.
Not to mention the money you can save in reloading components......and wasted time at the range by testing the wrong thing.
Does that mean I need to shoot 220 grain bullets out of my 300 Winchester? I'm not sure if my shoulder will take that. I always figured they would drop way too much at longer ranges, but maybe I am wrong. I guess I need to get out there and do some more experimenting. I have a range that I can shoot at about 700 yards. I appreciate your advice and help on this. It would take a lifetime to learn all this on your own.
Not to mention the money you can save in reloading components......and wasted time at the range by testing the wrong thing.
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I've practiced out to 600 yards with the rig (it's a sporter weight set up) and have taken game at 550.
I tend to prefer heavy-for-caliber bullets, but its not that crucial - again, lighter and faster is pretty close to heavier and slower. I have a 300 WSM I am setting up as a sporter and I plan on using 180 grain accubonds. Should be fine.
I used to think the same way, but realize, to shoot a 308 to 1,000, most use a 175 grain bullet. OR a 155 going really fast (pushing pressure limits). Its counter-intuitive, but true.
More weight with a good BC. Will have more retained energy at distance. The balance is between weight and BC.
We have all the books in stock right now - they tend to sell pretty quicly 
Also we have the DVD set Bryan makes - which covers some of the same material in a different way.
Also we have the DVD set Bryan makes - which covers some of the same material in a different way.Similar threads
