Gents, I'm thinking of Air Arms S510 for my next acquisition. Ads for the two show the two models Xtra FAC and the Ultimate Sporter XS make different power. The Xtra FAC .22=30 fpe and in .25=35 fpe. The Ultimate Sporter XS .22=32 fpe and .25 44 fpe (yes I know one is regulated and one is not, but I doubt the reg. is the source of the power increase).
Neither does the power I want in either caliber but the Ultimate Sporter is a lot closer to my goal than the Xtra. I don't want the 70 fpe in .25 one author says he got with port enlarging, but I'd like to make at least 34 fpe in .22 or 46 in .25. Hopefully one could get that improvement with just a bit of port drilling and turning up the reg. a bit (and installing one at that pressure in the Xtra of course).
I suspect that the Ultimate Sporter has larger diameter transfer ports to get the bigger power (and it shoots with lower pressure being regulated, so I would think it would have bigger ports).
The Ultimate Sporter already has it's breath hole drilled, so if I don't like it's plenum size for the power I end up at I'd have to get another tube. Additionally, I would want to swap out it's factory regulator for a Lane or Huma, so unless there is advantage in the Ultimate Sporter for some other reasons (more room to drill out bigger transfer ports, stronger parts, or?), the Xtra would be less expensive if I could open up the breathing and add a regulator and get the power I want.
I think the main maximum port size limit is the ability to drill out the variable power shaft/stem. Maybe that part is larger diameter on the Ultimate Sporter to allow a larger hole? Or is it the same part as on the Xtra and drilled out to a thin wall situation like the home tuner ends up with?
Long winded, I hope that makes sense. Thanks in advance for any opinions.
Michael McKeown
