The charging handle gives you a quick +1 ergo, and is 3,000 rb from Skier LL1.
The dustcover is also Skier LL1, and costs 6,300 rb. It typically gives +2 Ergo and -1 recoil over default dustcovers. Also allows you to mount many optics.
The handguard is from Prapor LL1, for 1,400 rb. It allows you to equip a foregrip, and also a tactical light / laser on it (not the largest ones though).
Short, quick guide. Happy hunting.