The 22a is the original, the 22a-1 was introduced in 2004, according to smith it has an improved barrel assembly to help prevent breakage when field stripped. A "bump" is a post that moves a thread to the top of the page in order to get more views.
When that spacer looks smashed and deformed, you will
notice the back of the pin hitting the back of the rear frame when its the spacer is wearing out.
Call S&W they have been known to send a batch out to folks, I haven't tried yet though.
I sent an email to S&W requesting a price for the buffers. I received an immediate reply stating that five buffers were on the way with no charge! Great customer service.
I recently bought a S&W 22A Talo Edition and it was junk right out of the box. Numerous failures to fire and failures to eject, and the grip was loose due to a faulty screw hole in the wood. I sent it back to the factory and they replaced the grip, the firing pin and spring which fixed the failure to fire problem but did nothing for the failure to eject problem. I sent it back again and they replaced the extractor, spring and ejector which mostly fixed the failure to eject problem. I would say it is about 98% reliable now. I have now tried several ammo brands and types which all seem to function the same in it.