VFC SCAR H/MK17 BufferV3 disclaimer: some filing might be needed on the rear of the lower receiver's edges if your bolt is getting stuck. you will also need to trim remove your buffer wall if isn't gone already otherwise the bolt will eat it. see pictures: (lower receiver picture courtesy of Lukem) V3 Sharper Recoil omits the spring for slightly sharper recoil impulse compared to V3 Spring. V3 Spring now released: it [usually] doesn't require tools to be installed