Well I just got a new 6505+ a couple days ago and when I went to band practice the other day I noticed a lot of feedback when I stopped playing. I'll give you a scenario, we were teaching our drummer a part to a song and when we'd stop to talk about it, there would be some crazy feedback and I had to turn the volume on my guitar all the way down. Should I play around with the ground switch or is this a just something I'm going to have to get used to with a tube amp?
It's a fairly common problem with high gain tube amps. Something like an ISP Decimator or Boss NS-2 in your FX loop will help a lot. The quality of your power and sources of interference (lighting, computers, etc.) may also be a factor, so a power conditioner MAY help.
Ibanez RGA121 | ESP LTD H-1000
Axe-FX Standard
Well if it's not happening when you're playing, I think you should (like already said) just get used to turning the volume down.

At higher volumes, almost all tube amps produce some noise, and a high gain tube amp is obviously going to produce a lot.
They are really noisy heads man. If its your guitar, run a gate in the front. If your guitar is okay, run it in the FX loop.
2008 Schecter C-1 Hellraiser
Currently amp-less!

Fund My GAS
Even Halen spoke about a story where Billy Corgan (I think) used his setup and was getting feedback because he didn't know how to handle a natural tube amp. It's something you get used to and isnt' a big deal, just make the volume knob a habit.
The 5150 has feedback from hell.

You need a noise gate if you're playing it any higher than 2.
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.

Will the ground switch help at all or do I just need to invest in a noise gate?
Quote by zhunt1130
Will the ground switch help at all or do I just need to invest in a noise gate?

Well try it out, and if it doesn't work than you'll know . Either way, if you start gigging, you're going to want a noise gate anyway. The ISP Decimator has been suggested, and if you are willing to spend the money, I think it would be a better idea in the long run than getting a cheaper one that may not be as good. I've been told to put it at the front of your FX loop, and you should be good to go.
Fender Hot Rod Deluxe
Gibson Faded V
Warmoth Strat copy
Epiphone Hummingbird (FS!!)
Ibanez SR400QM
Fender BXR100
Reggae Bass Covers mahn!!!