Well i bought an AT S400 Carbine .177 (new) last week and it is currently back at Air Arms to sort out a leak by the fill gauge. I have asked them to check the power and adjust accordingly if it's low (apparently they always check the power after working on a gun anyway). It will be interesting to see what power it's doing once i've got it back.
As far as AT goes, if i'm buying new then AT goes with the territory and i'll expect the manufacurer to sort any problems.
Non AT, whether pre or AT removed, have the absolute advantage of the responsible
owner being able to take care of any power creep. I've seen fellas checking their rifles before the WHFT shoot at Kelmarsh and finding that their rifles were either uncomfortably close (within .1-.2 ft/lb) to the limit or had crept over (by a smidgin).
I had a customer with a pre-AT S16 who brought it into the shop for a service. After i had returned it to Logun i had a phone call from Logun who informed me that the hammer spring had been pre-loaded with washers and it was over the limit. I said that as far as i was aware the customer wasn't an FAC holder and the result of that was Logun lowering the power back to a legal level and making the rifle AT.
On the other hand, I have a customer who seems to bring out the power in a rifle just by looking at it
. It really is uncanny how a rifle goes over the limit in his presence. He's had a Supersport returned to BSA for a new main spring and after it had been returned, we tested it and it was doing about 13-14 ft/lb! Another rifle he like the look of (Webley Blackhawk) and we tested it for power (he knows what happens with his luck now
) and it was producing about 13.4 ft/lb. That got sent straight back to the supplier!