Barrel length can increase or decrease FPS depending on your cylinder volume and air compression efficiency. Assuming very good air compression efficiency, you should focus on calculating your cylinder volume to barrel volume ratio which would involve math. I was actually involved in a thread not too long ago so I will refrain from re-posting the conversation here. This thread was originally posted no longer than 4-6 weeks ago. Search and you will find them.How will barrel length affect fps in bolt action rifles?
Your question about optimal barrel length can be better answered if you can give your personal definition of "optimal" in these contexts.But what is the optimum barrel length (regarding fps) for snipers (VSR10 and APS2)?
What do you mean by "help"?Also, does having a longer barrel and a larger cylinder help when shooting relatively heavy bbs