1.The Mar-10 currently weighs a whopping 10 Kilogram, however the wiki suggests it only weighs around 4.4 Kilogram, which should be more realistic and fitting.
10 Kilogram is too heavy especially for vanilla servers.
The gun is already meant to be rare and with scarce ammo, no need for further drawbacks.

2. The Scar H currently has less recoil than a UMP, this should be fixed. It's quite overpowered. It should copy the M4A1 model, but have increased vertical recoil