The air-rifle is for 10m Olympic discipline, which implies low muzzle velocity. But, I intend to shoot it at the regular air-rifle silhouette distances, i.e., 20, 30, 36, and 45 m/yards. Hence my question.
I also shoot air rifle silhouette and we compete with all three rifles, including Target rifles. Mine is an Anschutz SuperAir 2002 SSP and it shoots a 7.3 grain pellet at about 575 fps. FWB300's are another popular choice for Target rifle.
Set your scope zero for chickens (20 yds) and you'll go up from there.
Most Target rifles will need about 8 to 10 MOA elevation to get to rams. My scope settings are 0, 3, 5, 9 (in MOA). Environmental conditions might shift those numbers one or two clicks (+/- half an MOA) on any given day.
as mentioned before, you'll want to try some light domed pellets versus the wadcutters typically used for 10m paper. I suggest JSB 7.3's as a good starting point as that is what works best in my 2002. Don't be afraid to try the 7.87's or even the 8.4's, just know that it's going to take more elevation on the scope to get those heavier pellets out to rams. In the end, use whatever works best.
You don't need to worry about "knock-down power" for rams, even with a light pellet like the 7.3's. As long as you hit the ram it will go down assuming you have correctly-made targets. If you're using extra heavy targets then that may be an issue, but that's not the fault of the rifle/pellet choice.
Lastly, be prepared to pay close attention to the wind and to lean into it with the alignment of the shot. It's not uncommon to have to aim half-way to the next ram to hook it back in to a body shot. Also, pellets don't necessarily act like bullets when it comes to lift or drop based on left or right wind direction, so don't rely on those bullet-based "wind rose" charts.
I love air rifle silhouette and I'm glad we've got a good group of us that shoot it down here in the Texas and Louisiana region. We've got two big air rifle matches coming up in the beginning of the year... the North Louisiana Indoor Air Rifle Regional (a.k.a. the Coop Shoot) in late February and the Shamrock Silhouette Shootout (outdoor regional) in mid-March. If you're anywhere within travel distance then I highly recommend either or both of them!