mossberg 500 question

[BIGINNER]

i just bought a mossberg 500AG for $75.00  it has a 28in ribbed mod. barrel, my question is,.. what do the letters after the 500 mean? i want to get a barrel with removable chokes, so will any mossberg 500 barrel fit?  its chambered for 2.75 and 3 inch shells, would a barrel chambered for 3.5 inch work, or should i just stick with the 3 inch?  also,...  what are my options on threading the barrel?

[MikeWalking]

not sure about the AG  but any 500 barrel should fit...

Browse, didn't find 500AG on their web site..

http://www.mossberg.com/new.asp?section=products

Found some Threads on line...

It appears AG was just a Model designation back in the 80's selling for $120 then $99 and back up to $119  and if it's in good shape you got a steal. Some are going for $200 or more  Any 500 barrel will fit

[spookgus]

I would stick with the same chamber length. Even if they made a 3.5 inch chambered model 500 barrel, I doubt the spent hull from a 3.5 would properly clear your receiver during ejection. I think the A means 12 gauge and the G means that the original barrel had the C-lect choke system.