For a long time, a lot of experts felt that rifle bullets with a velocity of 5,000 feet per second or more were simply unobtainable. The .220 Swift, which hit 4,200 fps on a 40 grain bullet, was thought to be the maximum “regular” cartridge. Even the the infamous .22 Eargesplitten Loudenboomer supposedly only hit 4,600.
But now Banana Ballistics has evidently done the impossible, using a necked-down 5.56 NATO cartridge paired with an insanely light 12.5 grain solid brass bullet he calls “the Mouse Turd” firing out of a KAK 17-5.56 upper, he’s hit 5,157 FPS.
But that’s not the top! With what he considers an unsafe load, he hit 5,326.
And all that out of a 21 inch barrel.
I would like to calculate the trajectory of the round, but the online ballistics computer I tried tops out at 5,000 fps.
You may think a bullet that small is useless for anything but varmint hunting, but actually managed to punch through a half inch of mild steel.
It also tumbles more than a foot through a block of ballistic gel. Being on the receiving end would really ruin your whole day.
I assume many in the gun community will see a bullet that light out of a barrel that small as nothing more than a novelty, but 5,000+ fps is nothing to sneeze at.
Though I bet the round is hell on barrel life…
Tags: .220 Swift, Banana Ballistics, Guns, rifle, video
He didn’t just break the 5,000 fps barrier.
that little bullet left the barrel traveling at a mile per second. Damn. Velocity retention is pro
He didn’t just break the 5,000 fps barrier.
That little bullet left the barrel traveling at a mile per second. Damn. Velocity retention is probably going to be crap, but that is amazing!
The target-practice 120x570mm NATO tank gun loads generally exceed 5,100 fps at pressures in the mid 60’s. The war shots exceed 6,000 fps at pressures around 120 ksi. The 120mm guns have two advantages over this exercise: a sabot and a smooth bore, both of which provide higher velocities at given pressures.
momentum = mass x velocity squared. Going faster adds energy (in the form of momentum) much more significantly than mass. So it’s a lot lighter but packs a huge punch anyway.
As the first commenters noted, it’s going to lose that pretty fast though due to atmospheric frictions (gas molecules, dust, water, etc.)
“You may think a bullet that small is useless for anything but varmint hunting, but actually managed to punch through a half inch of mild steel.”
This seems like an exotic experiment with no practical application. But it may offer a niche advantage.
At short range, this projectile would likely defeat robust body armor. Since the cartridge is based on the 5.56.Nato.case, grafting it into the M4 platform is easily done. However, bolt thrust measurements would have to be performed to see if the tiny locking bolts on on Stoner’s design is capable of resisting shear forces generated duriing combustion..
A resident engineer would prove helpful with this analysis, but every since Kirk deserted this platform, we have been without competent help.
* “locking LUGS”
Correction:
Momentum = 1/2 mass x (velocity squared).
Been a while since I pulled that out of the memory banks.
Geck – momentum is M * V.
Kinetic energy = 1/2 M * V^2
Ammunition is heavy ~ if one is carrying a few hundred rounds. Soldiers on patrol would appreciate lighter rounds; as they appreciated light disposable magazines.
Geck, that’s kinetic energy, not momentum. Mass x velocity is momentum.
If you can hit and damage something with it, it isn’t useless. Nobody wants to get shot with anything.
If it’s also accurate snipers can use it.
No, momentum is mv.
Kinetic energy is 1/2 m(v squared)
“However, bolt thrust measurements would have to be performed to see if the tiny locking bolts on on Stoner’s design is capable of resisting shear forces generated duriing combustion..”
Bolt thrust is calculated by multiplying peak chamber pressure by the surface area of the base of the cartridge case. It is the counterpart of an IC engine BMEP calculation.
There is some debate as to whether the interior or exterior diameter of the case at its base should be used to calculate area, but generally the exterior dimension is used to provide a more conservative design value and to take in account radial elastic expansion of the system. Piezo instrumented tests usually measure a bolt thrust value between those calculated using the two different dimensions.
Stoner and Sullivan were both not very good at this calculation, which is why both the AR-10 and AR-15 bolts had to be reengineered.