Could keyholing of … seemingly this magnitude… be the result of basically laughably bad tolerances in internal barrel width, or perhaps the barrels are made of some kind of alloy that expands significantly from heat?
I have only ever seen keyholing in western gun videos from basically burn downs… but even then after a barrel is nearing its end of life by manufacturer specs, its more common to get some kind of failure to feed, significantly decreased precision and only occasional keyholes.
Maybe another possibility is similarly poor quality alloy of some kind used in the cartridge itself?
Combination of all of these things?
I remember seeing a fairly recent video of some kind of PLA MOUT type urban course… and you could see massive keyholing on targets that were like 5 to 10 meters away.
The prevalence of it baffles me. Ive personally dealt with and seen misfires and jams of various kinds at ranges, but I’ve never even seen a keyhole occur in real life.
I’ve seen a .22LR of mine keyhole. Once. Or twice. Ever. I honestly thought this was an AI imagine making fun of the PLA.
5.56 (especially M855 for some reason) also exhibits ‘fleet yaw’ for the first couple of yards when fired. Factory new barrels and ammo doesn’t matter, iirc something about the rapid application of rotational force from rifling and projectile construction
Fleet yaw is a different phenomenon that impacts terminal ballistic performance. It’s essentially a way of describing why some projectiles tumble and fragment after impact while others will tend to remain more stable and pass straight through for longer.
The projectile AoA being described in that context is only a couple of degrees. It’s enough to change how the round behaves after hitting something, but it’s not the type of in-flight wild tumbling that results in keyholing on a target.
This is an important clarification, you’re right. The yaw angle is minimal in ballistic flight, the level of keyholeing in the photo is rather dramatic. Though the 5.8x42mm is standard with a mild steel penetrator like M855, and the round was definitely built with cost as a major factor - maybe a bad lot of ammo?
On the heat issue prolonged fire would cause the metal to soften allowing for increased degradation of the rifling.
The easiest ways for it to happen would be either a poorly made barrel or a barrel not designed for a specific projectile. Different barrel twist rates are better for different cartridges. A heavy bullet is better in a faster twisted barrel. If you fired a very heavy bullet in a slow twisted barrel you would likely not have it reach a proper stabilization.
