R-9 maint

So I have an R-9 I bought about 15 years ago. Bought it form MAC-1 had him install a Bushnell 3x9x40AO and adjust the Record trigger. Shot a tin or so through it. It then hit the safe and has not come out until a moth ago or so. Co workers have told me, it has sat too long so I need to have it serviced. It seems to shoot ok but has quite a twang. Problem is its been so long I don't remember if it twanged before or not. Any suggestions would be greatly appreciated. Also do you folks recon an HW30s is backyard friendly in a city type environment. Thanks in advance.

Bob
 
Yes, the HW30S is backyard-friendly, ESPECIALLY in a city, due to higher ambient noise level. Works awesome on birds, but is marginal on squirrels, except with near-perfect head shots. Limit your shots to 25 or 30 yards though. 

Consider the Vortek kit for it, which adds a couple FPE of energy without wrecking the gun. I'm going to add it to mine soon. 

You can get an idea of how quiet it is in my youtube video review of it. (User Jeremy D)
 
I degreased the internals of my HW30S almost immediately after I bought it years ago. It too had some twang, bug after degreasing it, the speed increased by 40 ft/s and the twang was completely gone. All you hear now is a nice 'tok' after you pull the trigger. It's about as backyard friendly as you can get, when it comes to springers. Taking it apart is also easy.