Get it directly from Crosman Canada or D&L Airguns at approx. CAD$36.00 plus a couple of other cheap misc. parts.. There are a couple of threads currently running discussing this project in depth.
CR steel breech & tasco red dot, sounds like a good idea.
If you want to keep the 2240 light in weight use Crookedbarn breech and also has a nice bolt for it and you can eliminate the use of the barrel band which also will reduce the weight.
The Crosman steel breech has been around for a couple of years now I guess....ever since the AS2250XT came onto the marketplace. About 6 months ago, Crosman made a couple of small changes to the steel breech, but nothing major.