I know we are suppose to tune the buffer to keep from breaking the bolt hold open on ar15 lowers. But since i have the NFA/JBO lower and won't be using their upper since i already have an Anderson upper. Do i need to worry about buffer weight more of less? I currently have an anderson buffer tube with carbine weight buffer and a rifle spring in there. I did find KAK has a 50 dollar tune kit with different buffer weight but do i need it? This will be on a 5.5 inch barrel.

I am interested myself.

This is for 9mm?

From my research a heavier buffer weight is needed to get reliable functionality, from what I've read you may have trouble with such a light weight.

bolt catch breakage occurs due to the velocity that the bolt hits the catch on the way forward.  You want to tune your length of travel such that the bolt only goes past the bolt catch about an 1/8" of an inch give or take.  This reduces the amount of forward travel it has to pick up speed.

I don't have a lot of experience with different configurations; for my first 9mm build so far I just wanted it to work without having to screw around with it so I went with the JP SCS and bolt.  And it has been 100% reliable out of the box.  But it was spendy I won't lie.

There are some other threads on here about different buffer/bolt/spring/weight combinations and I'd advise looking for those.  Here's a link to get you started - Google AR15.com