I just got a Mec 600 jr from my uncle who has had it for years and never used it much. Everything I have is for 12 gauge only!

Here's what I have

-Mec 600 jr reloader
-box of Super X High brass shell casings
- 25lb bag of 4 shot
- '' '' '' 7 1/2 shot
- can of Win 540 powder
- can of WIN 571 powder
- can of IMR 700x powder
- 1 1/4 Charge bar
- 1 1/8 charge bar
- ? charge bar(Just has some etching on it) I'll have to figure out what it means!!
- A bunch of powder bushings
- Win white wads
- Win yellow wads
- Win Red wads
I know most of this powder is pretty old. Is it good?
Where do I find info on safe load combinations on the powders I have?
I've been looking through some info.....Is there something easy to go by?

Buy a shotgun reloading manual.

The powder should be in good shape if it was kept from getting moisture. I have some powder that is about 10 years old and I haven't had any problems with it.

Have you tried to contact MEC and talk to a tech rep? I'm sure they would be happy to answer any questions you have. MEC is good equipment. I've owned several of their presses over the years. They should also be able to send you a chart with all the bar numbers on, with amounts of powder and shot they throw, and should give you info on bushing numbers for adjustable charge bars. Good luck.