You're almost 100% going to have to strip that bugger down...
The problem with corrosive ammo is that it's a salt. Oils won't clean it out, and ideally it should be scrubbed anyways. If you do use oil, you simply cover the salt and stop it from reacting with oxygen and rusting. The minute the oil moves away from a spot, that spot will rust.
Because of this, the hot soapy water technique is used, because the hot water opens up the pores in the metal where the salts can hide, then dissolves and removes them. Then you can oil it all again. Plus, the really hot water will heat the metal and it will dry on its own.
The only way I can figure out for you to possibly clean it without removing the bolt assembly is to strip it down to bare metal in every other way (IE remove the stock, hand guards, and all other metal parts possible) then wash it as well as possible in a VERY HOT bath. IE - totally submerged. I don't know if you can get thick waterproof gloves to stop you from getting burned, but you'd need them. You'd need to scrub ever surface you can get a tooth brush or pipe cleaner into, and hope you didn't miss anything. Working the action a lot would help.
The pro's to this are that you wouldn't have to remove the scope mount.
The cons are that you might miss a spot, you might burn yourself, and you'd have a good chance of either missing some of the salt or missing a spot when oiling.
In the end, you can probably do it, as these guns are made to withstand use as a club. However, do you want to?
