And than there is always this:
https://mesatactical.com/products/en...ffer-mil-spec/
But that wouldn't allow me to get the planned XLT Extreme buttstock. So no added weight in the buffer tube and no really cool looking fully adjustable buttstock.

I don't know which would be more effective. A 3-4 lbs lead weight added to the gun or this recoil buffer tube. It better work very well because it's rather expensive.