I don't know how you had great professional standing at less than 3k rifle Tigerman, but you must have had some mad general skills to pull that off. I had 2.4k rifle and 4k handgun (both of them natural) before i reached "great".
I became great in professional standing in hg and ran around sweating a bit to see if i could unlock serendipity from a general or evade skillgain, but didn't get it until i went out and hunted a bit. I find that odd considering serendipity skillgains come most often for me during a defensive act.
Edit:
After browsing through this thread again i've found that there is good information but also a lot of confusion and misinformation. So for anyone wondering when they unlock a specific skill, i recommend checking
the wiki under skills, and then remembering this:
There are (at least) two different metrics for progress toward hunting skill unlocks. The first is professional standing, which can be found by hit ability as described by Paolo in the wiki and an earlier post here. This is used for unlocking such skills as marksmanship, serendipity, coolness & etc.
The second metric is completely independent of professional standing. It is your minimum damage with whichever weapon type you are most skilled with. This is what determines when you unlock skills that affect your minimum damage (imagine that
) such as RDA, wounding and killstrike.
Rifle and Handgun skill do NOT affect this minimum damage ability, so chipping them in will not affect when you unlock these skills. What will help are the weapons tech skills (laser weapons tech if you are a laser hunter, etc), anatomy, etc. As i understand it, weapons tech skills are the only ones that significantly affect both your professional standing and your minimum damage.