Obviously, the makers of discount ammo have the
means and the
motive to pull all sorts of tricks in order to make more profit. (Yes, even avowed Communist like Vladimir Putin have a Capitalist side !) Most shooters would simply say "Wow I can't hit the tin can today !". You'd need to be shooting at paper targets to even spot and recognize this phenomena. So kudos for being able to see this.
There are a number of reasons ammo might "keyhole". That is, begin to tumble head-over-heels in flight and strike the paper target sideways, leaving an oblong rather than round hole. The number one contributor is
Velocity.
I'm wondering if anyone has put this ammo over a chrono.