About 15 years back I picked up a used Remington M550, the forerunner to the 552 'Speedmaster'.
I suppose the recoil spring has weakened, because even though it does well handling S,L, and LR, it also feeds and shoots CB rounds.
Before moving, we used it to keep squirrels off the bird feeder. Pretty fun to unleash a tube of CB's at a running squirrel.
I bought a very nice Remington mod 550 a couple of years
ago at an estate auction. The 550 has a floating chamber
that increases recoil inertia to allow it to function with Shorts.
As I was getting ready to leave with it I was approached by
a guy who was even older than I am. He told me he was a fan
of the 550, had a few, and to try it with CBs. He claimed the
550s would function with CBs while the old Winchester 74s
made in .22 Short would not. A real fan of old 22s and the
Short ctg he had several rifles that used the .22 Short. I
also have several old rifles chambered for the .22 Short,
including a pair of Winchester 74s. My 74s will cycle part of
the time with CBs but not consistantly. The 550 will cycle
with CBs like the guy told me and so there's probably nothing
wrong with your recoil spring. The design of the 550 does
lead to fouling build up with lots of use so it needs to be
kept fairly clean. These old .22 rifles are fascinating guns to
use or just play around with. There are countless numbers of
them out there floating around so it doesn't cost an arm and
a leg to acquire a few.
