Optics Planet has a "Valiant Optics Lynx 6X40mm" with AO, which is under $100 and says its "shock proof" but I doubt it is springer rated. I'd post a link, but I don't have the know-how. You could take a gamble, but honestly it would probably be better suited on a PCP or a PB.Most fixed scopes aren't favored these days, I'd very much like a fixed 6 or 8 power springer scope. Companies have to produce what sells, and these days 3-9, 4-16, 6-24 or whatever up to 56X (or more) is what's "hot". On one of my AG's I mounted a Burris 4.5-14X (42mm objective lense), the parallax adjustment only goes down to 50 yards. 99% of the time it's on 8 power, which works well between 20 to just past 50 yards (and probably further). I can deal with the minor parallax error, what little there is and I find the sight picture to be very clear.
SWFA makes some good ones in 6x, 10x, 12x, and 20x. I just got a used Weaver T36, I think I like it. I will be looking for a couple more for "spares".
I find 4X isn't enough for all-around use. 6X is marginal, somewhere in the 8-12X range would be perfect.
i was looking for a fixed 6x scope for a long time and couldn't find one. i bought an 8x for the Brocock Contour. a bit more magnification than i wanted for squirrel hunting, but without the extra lenses it has much better light transmision. it also comes in fixed 10x version. i'm not sure if it's springer rated though.https://airgunopticsplus.com/collections/scopes/products/copy-of-discovery-optical-vt-2-10x44-sf-with-mil-dot-reticle-fixed-power-rifle-scope