Thread: Explain why please

First let me say I have no great understanding of ballistics etc and dont reload so please explain in words of three syllables or less
I have a Marlin 30-30 and use the Leverolution 160 gr FTX ammo .I consider I shoot very well with it and can get a nice tight group at 100 mtrs and with it sighted at 1 inch high at 100 I can get a 3 inch group about 2 to 3 inchs low at 200 which for my shooting which is all North Island bush is great and have shot quite a few deer with it now
In the latest reloaders mag I see Hornady have bought out a 140 gr Leverolution round so I get all excited thinking beaut faster ,flatter longer .No! Reading the specs on the Hornady sight its MV is only 65 fps faster ,energy is only 57 flb's less and trajectory is virtually identical
How can this be ,can someone tell me .Its $10 a box dearer for no added gain as far as I can see

The slight gain in speed is offset by a worse balistic coefficient.

So it starts off a bit faster but slows down faster also, net result same same at the ranges your talking about.

65fps does seem very little gain tho.

I see the Ballistic Coefficient is different 160 gr is .330 and the 140gr is .277 .What determines the coefficient I would have thought that the projectile would be identical in shape etc only different weight ,but as I say I know nothing about ballistics

Originally Posted by Old Bastard

I see the Ballistic Coefficient is different 160 gr is .330 and the 140gr is .277 .What determines the coefficient I would have thought that the projectile would be identical in shape etc only different weight ,but as I say I know nothing about ballistics

Put very simply "how pointy it is" , most likely they will have exactly the same nose shape but the 160gr will be slightly longer(because it is heavier ) and therefore is "more pointy"

Another way to think of it is they both have the same shape nose but one has more weight pushing it threw the air so will slow down less.

thanks guys understand it better now the ping pong / squash ball analogy is enlightening .So why would you bring out a round like the 140 gr if as I see it gives you no advantages or benefits or am I missing something

It could possibly have very slightly less recoil or stabilize better in slow twist rifles.

More likely its just to fill a gap in the range for people just want a 140gr.

Originally Posted by Old Bastard

I see the Ballistic Coefficient is different 160 gr is .330 and the 140gr is .277 .What determines the coefficient I would have thought that the projectile would be identical in shape etc only different weight ,but as I say I know nothing about ballistics

3 things determine the BC (courtesy of Mr Litz)

WEIGHT: The heavier the projectile, the higher the BC, because a heavier object penetrates air better than a light one
CALIBER: Cross sectional density - a narrower bullet penetrates air better
FORM FACTOR: A measure of how streamlined the bullet is. It compares the projectiles drag to a standard bullet. The most common "standard" bullets are the G1and G7 shapes.

Originally Posted by 7mmwsm

I probably know a little less than you about this stuff but I think it is all to do with kinetic energy.
Throw a ping pong ball and it starts off fast but slows quickly. A squash ball, which is roughly the same size but heavier, thrown at roughly the same speed has extra weight to carry it on.

Dont know if thats a totally good example.Say you threw a squash ball compared to a round piece of heavy steel the same size which weighted alot more. The lighter squash ball will not slow quicker than the heavier piece of steel will, which is the opposite to a lighter ping pong ball example. Other factors come into play other than weight and size

Originally Posted by deer243

Dont know if thats a totally good example.Say you threw a squash ball compared to a round piece of heavy steel the same size which weighted alot more. The lighter squash ball will not slow quicker than the heavier piece of steel will, which is the opposite to a lighter ping pong ball example. Other factors come into play other than weight and size

The Old bastard that asked the question has just left my place and is confused enough already

Originally Posted by deer243

Dont know if thats a totally good example.Say you threw a squash ball compared to a round piece of heavy steel the same size which weighted alot more. The lighter squash ball will not slow quicker than the heavier piece of steel will, which is the opposite to a lighter ping pong ball example. Other factors come into play other than weight and size

Yes it will, it just won't be as noticable as the extreme example of the ping pong ball as the mass of the two is closer together as a percentage. All other factors being equall like shape, size and surface texture of course.

I think it comes down too whether you would rather be hit by a mini going fast or a fully laden dump truck going slow. End result would most likely be the same

Originally Posted by mikee

I think it comes down too whether you would rather be hit by a mini going fast or a fully laden dump truck going slow. End result would most likely be the same

Differences start showing up when it anything other than a perfect T-bone side-impact

Or you could just go for the medium sized family saloon, traveling at a reasonable clip.

P.S. Go the mighy 308 flying pig

Originally Posted by ebf

Differences start showing up when it anything other than a perfect T-bone side-impact

Or you could just go for the medium sized family saloon, traveling at a reasonable clip.

P.S. Go the mighy 308 flying pig

Thats the route I am currently going with my new rifle but have upgraded the "motor" a bit and added some flash harry wheels