I vary my BB weight a lot as at our site distances vary with each game (Airborne Airsoft at Longmoor, Liss, fun site, smaller distances and lots of shorter games)
For CQB village, 0.25's are my go to, not to expensive and faster than heavier rounds so they get less time to dodge back. run a SRC G36c (modded) for that. 450 round mag and we tend to run 30 min each way games so 1 mag normally just covers it
Smaller woodland games with 50m range max, again SRC G36C running 0.25's. But I carry 0.4 in my side arm (SRC B92 or SSP1 depending on day), same for the larger village
We have one unique game on a steep hillside, with a landing craft attack from base to a rapier missile base at top with trenched defenders. That I mix it up. For defence I plug a 2000 round drum mag on the G26, extend the tripod and run it as a SMG on full auto, I run 0.2's for that cos easy to get through 2000 round in 30 mins, its just suppression fire down the hill so range and accuracy are not the issue, its just plastic in air!
On the attack I will use my SSG24 with 0.4 (optimum energy weight with M140 spring to meet site limit at 0.2) and snipe the defenders from a safe spot. max distance is around 70m so the SSG24 is very effective while I can hide in Landing craft. Or else I will use the G36C, with 0.3 to give me a bot more range and accuracy up the hill
