[member548]

First of all I freely admit I know almost nothing about reloading or the physics involved with ammo pressures.

That being said I'd like to know with modern technology and materials why we don't see ammunition the size of the 5.7x28mm yet still capable of pushing a 40 grain bullet to well over 3000fps.


I'm surprised they haven't moved beyond brass for high end military weapons. I bet spec ops would love a gun that had ammo as compact as the 5.7 yet had the same or more energy then 5.56.

Maybe some titanium shells loaded with some kind of higher powered propellant fired from iconel chambers/barrels.

Maybe it's just a cost issue, but it seems odd that I've never seen any mention of moving away from what amounts to over 100 year old materials and technology.

 

[Fred G Sanford]

I would believe that cost would be an issue. When regular weapons work so well, why spend so much on such a weapon? Titanium is not cheap. And, the weapon would have to be built to withstand greater pressures.

 

[iwannausername]

Well,OAL, etc. aside, there is the 220 swift. And sabot rounds for various 30 cals, all cranking 55grn .224" pills out at 3500+fps

The problem is that even with a massive chamber, etc. so that pressures arent an issue, the fuel (powder) has to fit in the case, and be able to burn fast enough to quickly crank the pressure up, but at the same time, still be able to burn most/all of the fuel before the bullet gets out the end of the barrel.

Now take the massive chamber away, and scale the cartridge down to something reasonable, etc. and it just won't happen. We've got the metallurgy, it is the fuels that need work.

 

[devildoc]

On a strickly medical point of view, having a bullet go fast is great as long as it will rapidly destabolize while retaining it mass on impact. A round that punches a small hole that goes through and through does little good. I cant remember the calculations but it trauma there is a math equation that the mass times the speed = potential energy. Anyway, if a round is going 2000 fps hits a target and stops inside the target all the energy is released, where as a round going 3000 fps that hits a target and leaves at 1200fps actually does less damage. I cant remember the exact formula that is used.

Titanum would be extremely expensive. The bullets wound be worth more than the gun that fired them.

Now teflon coated ceramics with an aluminum or lead core for the military would be interesting.

 

[kanthek]

Actually its kinetic energy. Potential energy is stored energy.

The formula E = 0.5 • m • v2
(This is a general formula for kinetic energy - not the one used for muzzle energy which is modified to account for different units of measure. I used an online calculator for this)

If you run the numbers you gave in your example:

Assume the bullet is 55 grains (a .223)

at 2000fps you get 488.5 foot pounds
at 3000fps you get 1099.1 foot pounds
at 1250fps you get 190.8 foots pounds (a net decrease of 908.3 which is almost double the 2000fps one)