Snow Wolf M99 Parts

So, I took this sucker apart, and was glad to see that it's mostly APS2 inside, with a few alterations. The piston sear is clearly made out of a different material than the typical Chinese pot metal, it actually looks to be some sort of a nice steel alloy.

The cylinder and all components are APS2 style, very cheap plastic on the piston already worn after 1 magazine, definitely something that needs to be upgraded.

The hop is a modified standard APS2 hop, with an arm much like the VSR with 2 pressure points (like an SCS). Seems to have good compression, and I'm fairly certain with a little shimming of the hop arm that it would improve the left/right consistency greatly.

Basically, I'm curious as to what options there are for upgrading the barrel/bucking without upgrading the hop up.