Well, if you can use a straight edge/ruler to check the miss-alignment,
then I guess you can use a caliper or similar device to check and see
if the top rail has the same thickness front and rear.
If it has, then you can safely assume the top rail is parallel and
it is not the cause of the miss-alignment.
Try to check it and see what you find.
There are many people posting the facts you just found on your SR-22.
The real reason for that typical case of miss-alignment
is a glitch in the design of the stock.
There are 2 bolts holding together the
front and central pieces of the stock.
These bolts (screws) are very low compared to
the center of the parts they are supposed to tighten together.
When they are tight, the handguard may droop a little.
Over-tightening them will actually make the matters even worse.
Take apart the front and the central piece of the stock
and inspect the mating surfaces.
Make sure there is no dirt/paint or whatever between them.
Re-tighten the bolts without using un-reasonable force.
About your other problem, the gap between the top rail and the receiver rail.
I suggest you screw the large nut as close as possible to the front piece of the stock.
Also, screw the handguard tube more on the large nut.
Lock it against rotation using the lock ring.
Loosen the top rail screws and move the rail rearward to close the remaining gap.
PS: I suggest you learn how to post pictures from your photobucket account
and do not allow visitors to see the whole album, especially if the album contains
construction detail of your vault or safe door/lock that you don't want them to see.