[metallicafatcat]

You should be using the highest quality BB you can effectively lift. Just as a heads up, your probably going to be shooting hotter than 450, just my speculation.

 

[metallicafatcat]

Most consistent BBs are the machined ones, or SGMs, how ever, I personally doubt the capabilities of a GBBR as a DMR without an HPA rig, but I love to be proved wrong. Just start with .28s and move from there. Some guns only like certain ammo, it's not cheap, but I'd bet you'd be able to buy handfuls of different BBs from local snipers.