i've done what SRT does, put bullets on and taped the packs together so i now have a 6s pack and a 4s pack, godd thing about it is i can add more packs if i want

quick update on bullets

if you get the ones with shrouds, drill the inside of the shroud to 1mm larger ( ie - 4mm bullet, 5mm drill bit) you wont get the heat shrink all the way on but you can get a bit on, i used 20mm heat shrink around the wire and shroud for extra grip to stop the bullets coming out