Just a reference for me to machine out a 6061 custom buffer for AIRSOFT VFC GBBR HK416A5 V2, should work with v3 and WE-Tech AR-15 style gun just fine.

You might need to edit/mod a tiny bit with the max diameter, made it 25mm but it should have some tolerance so make it around 24.9ish. Same with the inner hole, I only eyeball it, but you should be able to make it any size and length to get the perfect weight you want.

I wouldn't recommend printing this to use in your gun for extreme light weight buffer, I made another version that you can print but depending on the weight it might cause bolt bounce, so keep that in mind. - https://www.thingiverse.com/thing:6746571

This is made for airsoft any damages, injuries or misuse of this design are not my responsibilities.