The US Army revealed plans to develop a new approach to bolt and chamber design that would allow cartridges to be loaded to insane pressures (up to 100ksi compared to today’s 62ksi for 5.56).
Among their goals is hypervelocity for extended range lethality from standard sized weapons, and full-sized rifle velocities with firearms that are half the weight, half the length, and hold more ammunition than the Army’s M4 carbine.
“The goal is to get rifle-like velocities out of a very small weapon that is high capacity, that’s either adaptable for room-clearing or confined spaces,”
The muzzle velocity was over 2,900 feet per second, outperforming similar short barreled weapons like the FN P90, which rates at 2,350 feet per second at the muzzle.
(T)he U.S. Army’s new 24-inch prototype barrel produced muzzle velocities of 4,600 to 5,750 feet per second.
This is all centered around a new bolt lockup design that uses a screw (hasn’t this been common on artillery pieces for over a century? Why is this just now being tried in small arms?) and a collet surrounding the brass case to keep it from expanding against the chamber wall so tightly that extraction becomes impossible. They’re also playing around with tapered barrels which has me curious about what they’ve done to prevent barrel wear with these absurd velocities and the obvious increase in stress and friction associated with tapered bore designs. The drawbacks in terms of durability are obvious as many of these ideas have been tried in the past only to be abandoned as the best materials available still were not enough to overcome the increased wear associated with hypervelocity speeds and pressures. Maybe they’ve made some sort of materials science breakthrough in terms of barrel material? A ceramic coating perhaps? It’s still a very neat development that could result in a huge leap in firearm performance if it pays off.
(the story is a few months old but it’s news to me)