[sop2510]

Most of the discussion on the ammo threads focus on velocity, but I rarely read anything about muzzle energy.

Does the old 1/2mv(squared) formula for kinetic energy not matter that much when it comes to low-weight, high-velocity bullets?

Sorry if this has already been answered, but my senses tell me that a 180 gr .30-'06 round out of my old Garand will knock them down just as well as a 90 gr 6.8 mm out of my Mini-14.

Okay, so I only have eight rounds in the Garand instead of 20 in the Mini, but there's got to be more to it than that.

I stand ready with open mind to be informed and enlightened by you kind folks on the forum.

Bob Ciminel - Roswell, GA

 

[marinesg1012]

It depends on what your shooting and how far your expecting to shoot. The extra velocity with the same bullet gives us an extended range as compared to the older rounds which is why people talk about it as much.
The 6.8 using good bullets will carry 1K of energy out to 400 yards, all in a lieght weight semi auto platform with minimal recoil. Thats where the rifle shines as compared to the larger calibers.

 

[Desert_AIP]

Velocity squared is the key.
A large increase in energy for a small increase in velocity.

Double the mass, double the energy.
Double the velocity, quadruple the energy.

More velocity gives you less drop at a given range because it gets there quicker.

On the other end of the calculation is momentum which is mass*velocity (not squared).
That is where a heavy bullet shines because the bullet sheds velocity but not mass (until it strikes something of course).

 

[sop2510]

On the other end of the calculation is momentum which is mass*velocity (not squared).
That is where a heavy bullet shines because the bullet sheds velocity but not mass (until it strikes something of course).

Forgot about momentum. Excellent point. That's why I opted for the .458 - lousy range, but one heck of a wallop, and all on a AR-15 platform. I just hope I live long enough for RRA to make and deliver it.

Don't get me wrong - I'm a full-blown 6.8 lover. That will be my next purchase, based on recommendations from this forum. In the meantime, I'm having a lot of fun with the Mini-6.8 almost every weekend.

Thanks for the prompt reply, Gents.