I recently bought a new Gibson SG Standard from a local shop. The guitar sounds great but when I am on the bridge pickup it will cause bad high pitched feedback unless I use my fingers to stop the strings. I know that that's not really hard to do to stop the feedback but I was wondering if that's normal or not. If the strings are untouched it causes the feedback horribly.
take it back and have them fix the grounding issue your having. They will probably (and should) do it for free
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How loud is your amp, and how close are you standing to it? This could just be normal if you have a really high output pickup in the bridge.

Other than that, it's probably just a loose ground somewhere, which is a 30 second job to fix if you have a solder iron.
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