The really big innovations incorporated into modern firearms have been developed incrementally over a couple of hundred years - rifled barrels, primer caps, smokeless powders, the self-obturating (breech sealing) cartridge case, self loading mechanisms etc.
Most of these were well established by the first couple of decades of the 20th century. Firearm design since then has consisted of variations on the same theme, and we’ve had two world wars to develop and pressure-test designs. It’s not too surprising that rifles developed in the post-world-war-2 decades are still contenders for the best infantry weapon. There have been a few developments in materials, particularly polymers, which have cut weight and improved reliability (the HK G36 and Steyr’s AUG are both good examples of this) and the bullpup layout has allowed overall length to be reduced, but nothing as earth-shattering as the self-enclosed cartridge has been introduced for the past 100 years.
The only real attempt to “think outside the box” in recent years was made by Heckler and Koch and Dynamit Nobel with the G11 and the caseless cartridge. I have vague memories of an old magazine article detailing a design spec for a rifle which could fire a three-round burst at >2500 rpm and land all three inside a 70 cm diameter circle at 600m, the idea being to increase the average grunt’s hit probability at longer ranges. This rate of fire could be more easily achieved by dispensing with the need for case-ejection, and so a solid block of propellant with a bullet stuck in one end and a primer cap stuck in the other was developed.
The G11 breech has to obturate mechanically, and there were problems with fresh shells “cooking off” when loaded into the hot breech and other reliability issues. According to H & K, the problems have been solved and the current prototype is a shit-hot, viable rifle of the future. I’ve read some pretty disparaging things from other sources, but it’s hard to tell if these are based upon real concerns or excessive conservatism.
Flechettes, or “nails with tails”, seem to be an attempt to put the tank-gun’s APFSDS ammo into a bullet. Their needle-like profile should give good penetration of body armour and light armour, and their length should make them tumble nicely within a soft target, essentially cutting a slot and maybe snapping in half for good measure. Nasty, but maybe a solution looking for a problem - current AP rounds do a good enough job vs. light armour.
The effect of the 5.56 NATO round is detailed in the following article:
"this full-metal-jacketed bullet travels point-forward in tissue for about 12cm after which it yaws to 90°, flattens, and breaks at the cannelure (groove around bullet midsection into which the cartridge neck is crimped). The bullet point flattens but remains in one piece, retaining about 60 per cent of the original bullet weight. The rear portion breaks into many fragments that penetrate up to 7cm radially from the bullet path. The temporary cavity stretch, its effect increased by perforation and weakening of the tissue by fragments, then causes a much enlarged permanent cavity by detaching tissue pieces. The degree of bullet fragmentation decreases with increased shooting distance (as striking velocity decreases), as shown in Fig. 5. At a shooting distance over about 100m the bullet breaks at the cannelure, forming two large fragments and, at over 200m, it no longer breaks"
From: “Wounding Patterns of Military Rifle Bullets.” Martin L. Fackler, International Defense Review, 59-64, 1/1989. (This article was available online at one point but gives a “cannot connect to server” error at the moment.)
The text refers to the older M193 bullet designed to be fired from the M16A1, and states that its tendency to hamburger the target was accidental and not initially understood. However, the current SS109 fired from the M16A2 does the same thing and I’m cynical enough to believe this feature may have been left in deliberately. Interestingly, the German NATO 7.62mm does the same thing but the US NATO 7.62mm doesn’t the jacket is thicker at the cannelure.
