Drew posted pics of cracks in some American classics...here is a 1937 Sterly I tracked all the way back to the rear tang.
The PRE-SAVAGE, prior to 1930 manufactured, "Fox Built" Sterly's had a factory corrugated nail placed horizontally in that 'crack likely' ROTARY BOLT area just for that reason.....I guess Savage dropped that to save some cost....i.e. the result is as you have pictured.....
The Fox built guns, pre 1930, will usually "hair line" crack near the side panels where the receiver fits very tight and firm against the
old wood.....if heavy loads are used consistently ......glass bedding of course helps........