Assuming air rifle silhouette competition still resembles what it was when it went extinct in my area two or three decades ago, hopefully my three decades of silhouette competition (before then) might be of some help (rather than hindrance). Back then there were three classes in NRA Air Rifle Silhouette competition. I'll only comment on Sporter Class, lest I be speculating like someone with no silhouette experience.
NRA Silhouette was an
all-offhand proposition. In other words (mine), "shooting from your own two feet LIKE A MAN!" However, that all-offhand requisite, in itself, demands some discussion.
From what I could see, back then my (now deceased) brother and I were the only ones shooting NRA Air Rifle Silhouette competition in Texas from what I call the "
true offhand, Daniel Boone" offhand style; that being with our elbows resting against nothing but thin air. Everyone else rested their off-elbows on their hip or gut for additional stability. That explains why the NRA weight limit for "Sporter" Class rigs increased from 10 pounds, 5 ounces to 11 pounds; because the Powers That Be were using heavy, state-of-the-art springers with heavy, high magnification scopes, and struggling to keep their "Sporter" rigs under the weight limit. So
of course they increased the weight limit, to better advantage themselves. Obviously the additional weight helps those resting their off-elbows.
Being 'heavily' into vintage-collectable airguns at the time (and still), most-
smitten with vintage Crosman Co2 guns in .22 caliber, and determined to expose the "performance
at any price" mentality and blind allegiance to .177 caliber as (effective) brain-washing, I used a 1950s vintage Crosman 160 .22 caliber Co2 rifle equipped with a 2-7X scope... with my elbows resting on nothing but thin-air, "Daniel Boone style". My SPORTER class rig weighed less than six pounds;
little more than half that of my competitions' rigs.
Besides the State Champion title and NRA National Record certificate pictured, that old .22 Crosman Co2 rifle also led my Sporter Class Team (of three) to two more NRA certificates- for Forty Shot and Eighty Shot NRA National Records. My team-mates used a .177 Whiscombe and a .177 Air Arms TX200; however my (higher) Crosman 160 scores led us to the national records.
POINT IS, offhand shooting being SUCH a challenging discipline, and so related to shooting form(s), personal preferences become exponentially more important than many/most other shooting disciplines. And though I realize my experiences more than a little "dated", I suspect the advice is still sound. At least probably more so than speculation.