Originally Posted by mcguyver
[the majority of airsoft] Guns are too inconsistant to apply a simple formula and expect to get the right answer all the time. Sometimes it works, but that's luck.
Actually, there are a number of correct things posted in this thread...and a little misinterpretation by some of what others are trying to put forward.
I ran a bunch of velocity tests when setting up a buddy's rifle for both CQB and outdoors with a single mechbox (I found playing with the barrel length far more interesting than fiddling with other variables).
It was boring and I'm not convinced of the results. Despite efforts to keep the tests practical and consistent...there are a lot of variables that come into play. I might repeat the tests again this winter if I get really bored...but I'd have to be really, really bored and it's basically a waste of money and time.
It sounds great and simple to say..."When you switch between 0.20g and 0.25g bbs, you'll drop 30fps"...but there's such a variance that even 10fps on a 400fps rifle is just 2.5% of the overall velocity and so pretty inconsequential given the system...and anyone who has tried to do these types of tests knows how easy a 10fps spread pops up. With a lot of data you can start to see trends...but what to do with the spread/%error? The comment becomes..."when you switch from 0.20g to 0.25g bbs, you'll get a 20-40fps drop" and starts to become useless as a guide line.
Extend this to encompass the fact that one airsoft gun's compression and setup can vary wildly when compared to another...and it's a very rough guideline at best. (I.e. take Stalker's uber +/- 1fps target grade bolt action and extend the results to a Kraken)
What is valid...is for each person to try out different BB weights and then to say..."In MY setup, going from 0.XXg to 0.YYg resulted in drop/increase from ABCfps to XYZfps". Unfortunately those results are limited to your rifle...and lose validity for another.
So far as GBB's...heavier bbs work better. With all the "target"/IPSC/CAPS shooting lately...it's painfully evident that when you want to shoot better than MOB (Minute of Body), and you want to shoot a consistent sub-palm size cluster...you shoot heavier BBs. Zero controlled tests to back this up...just practical observations. So far as what weight hits harder...that's easy to see after a night at the range...heavier BBs punch though the patched up metric targets better than the 0.20g lightweights that are often stopped/stuck in the target cardboard. ***edit*** but obviously simply switching to heavier BBs won't make an inaccurate GBB shoot like a tack driver***
To address the original question...heavier bbs hit harder than lighter BB in normal field/engagement ranges. I know this because I've been shot a lot. I also know that you should load 40mm grenades with lighter BBs...because they sting like a MoFo when you get blasted up close.