What's Ballistic Coefficents??

benson821

benson821

New member
I'm going to start reloading here in about a week and I currently shoot a 270 win. (tikka t3 lite). I ordered Sierra 135 grain Matchkings Boat tail hollow points, and I found out the ballistic coefficents of that round are:
.488 @ 2800 fps and above
.482 between 2800 and 2000 fps
.440 between 2000 and 1500 fps
.390 @ 1500 fps and below
I will probably be shooting them around 2000 to 2800 fps, and I have the somewhat crazy idea of using this rifle for long range shooting/hunting? would this bullet be good for that?

My dad has an AR with a 1 in 8 twist and he ordered 52 grain A-max's and it has a ballistic coefficent of 0.247 we will be using them for game from coyote and smaller, and 500 yard or shorter shooting, will these bullets work well for that purpose?

I don't really understand ballistic coefficents so if somebody could explain what the numbers above mean it would be much appreciated.

Thanks,
benson821

(P.S. I like this fourm, I am a member of other fourms and this one is my favorite, other fourms people are disrespectful to people asking questions, but everybody here knows what they are talking about and are very helpful THANK YOU)
 
I'm no good at explaining the numbers game.

A simple way to look at it....
The higher the number the better it slips through the air.

poly tip and boattail = less "drag"
 
If you really get into studying ballistics, then watching the BC is important, but in general as Tim said--"The higher the number the better", but it's not always "THE" most important thing to consider about a bullet. If your hunting deer and larger animals, you'll want a bullet that stays together and expands. That often means that you might end up using a bullet with a slightly lower BC.

As for long range shooting and varmint hunting, what your doing should work well. The match bullets may not open up on larger game but should be good for paper and varmints. I shoot a 25-06, which is a flat-shooting cousin of your 270. Your selected bullet weight, whatever you try, will also be a balancing act between velocity, wind effects and other forces on your bullet. A lighter bullet like the 110gr Sierra will allow you to push your velocity over 3100 fps, which could will help you reduce bullet drop at longer distances. But the 130, 140 & 150 gr slugs will start slower, be affected less by wind, will drop more at longer distances, and yet retain more delivered energy.

With the right scope, your 270 can easily be a good shooter out to and probably past 600 yards.
 
Last edited:
Originally Posted By: Tim NeitzkeI'm no good at explaining the numbers game.

A simple way to look at it....
The higher the number the better it slips through the air.

poly tip and boattail = less "drag"


+1

Yep, that's the short of it. And a "General" rule of thumb is the heavier the bullet the higher the B.C.. However there are projectiles out on todays market that have very high B.C's and low overall projectile length allowing you to push them a little faster, one that comes to mind off the top of my head is the Scenar. The .30cal 155gr Scenar has a higher B.C. than the 168gr SMK.

If I were planning on using my fast twist .223 to 600yds, I would look at the 75gr A-max first then possibly one of the heavier VLD's.


Chupa
 
laymans terms
how efficiently it cuts through the air
like comparing a Porsche to a boxy station wagon.
like already mentioned the heavery the bullet the less the wind can blow it of off it's course but the slower it getts there
a balancing act for sure.
Mike
 
It is a measurement of how effciently the bullet travels through the air. It has a direct impact on down range performance and how much energy the bullet loses as it travels through the air.
 
So would the 270 round I got with a B.C. of (look below) be a good round for 500-600 yard shooting?
.488 @ 2800 fps and above
.482 between 2800 and 2000 fps
.440 between 2000 and 1500 fps
.390 @ 1500 fps and below

What about the 52 grain A-max? with a B.C. of .247 be good for the same purpose?
 
What you need to do is find a ballistic program to enter your data.. Then you can graph the theoretical performance of your bullet.. You also need the weight of the bullet..

The ones you listed for instance , the .488 BC will carry more speed over a longer distance, hence less drop..

The 52 Amax has half the BC of the one listed @.488, hence it will drop faster and farther compared to same bullet with a .488 BC..
 
Your .270 will work well for 500-600yard target shooting.(If you can find an accurate enough load). People will argue about the 52 A-max, I say it works depending on your tolerances. It will have much more drop and more wind drift then your .270, but it isn't exactly going to just quite moving. The answer to your questions lays in what your tolerances are. Are you shooting F-class in competition or at rocks in the desert?
Shoot both at 500-600 yards and have fun.
 
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