frame
On mine which has a 314xxx serial (bryco arms Jennings J22). The serial number is located on the frames left hand side towards the rear. It is beneath the slide behind the safety and grip. PS: I have seen some J22's that do not have the s/n stamped in this location so yours may be different.
Yes, a Jennings J22 will fire without a magazine inserted.
Probably not. IIRC, the Jennings company is out of business as a result of lawsuits. The J-22 was made from about 1981 until the company was sold a few years back, and I know of no serial number records for them.
Best thing is to have a gunsmith show you.
Recommend you ask a gunsmith for help
These retail for about $85 new.
The thing that keeps the slide on a j22 frame that won't stay on is the slide catch. It is designed so that the slide mechanism can be locked in place without risk of it moving.
serial number mavis beacon
Serial number.
Best to ask a gunsmith for help if you don't have a manual
the serial number is on the back
The serial number of the titanic is 16458990231