Dude,
First of all -- there's no such thing as "kill stealing", if they can't finish the job -- it's your obligation to do so for them
There are alot of guys who choose to fly the "nibblers", like Hurricanes, I-16s, etc -- because they like to turn-fight. Like you, I fly the 109s and have my hands full getting a shot on these guys -- but when I do hit something (in the G6 and K-4) it usually dies. It's not your fault that it takes them 10,000 rounds to bring a plane down -- they need to fly something with more firepower if they're worried about someone finishing a plane that they've been nibbling on.
At the end of the day -- its just a video game anyway -- for relaxing and having fun. Anybody who yells at you for any reason is a tool. Either yell back at them -- or just switch off your mic. I usually just laugh into the mic when someone says something stupid
