First off, I want to thank you for your service to our country! And welcome to OCDO. We've got a GREAT group of people here, and many wise folks with a LOT of experience and knowledge in the law.
Kangaroo's advice is sage--DO NOT volunteer any info to LE, past what you are required to do--which isn't much more than stating your name verbally.
NEVER consent to a search or to them "seizing" your firearm. Don't fight them if they demand doing it--but make sure you verbally object to their unlawful and non-consensual search and/or seizure of your property.
And ALWAYS keep a small digital voice recorder on your person when you OC if you are worried about some rogue cop hassling you. Considering the fact that you will be seen as a "BMWAG", as opposed to a law-abiding citizen, carrying a voice recorder is probably a REALLY good idea--They don't cost much, and can be worth their weight in gold if your rights ARE violated.
About the only incident I can think of where a YBM (Young Black Male) was assaulted by PPD in association with a "gun"" was the case of Jordan Miles in early 2010. Three plainclothes PPD officers saw him walking down the street with a "bulge in his pocket", and started shouting, pursuing him, and brandishing firearms. The boy ran, fearing for his life, and when they caught him they beat the tar out of him, only to find that the "bulge" was, reportedly, a bottle of Mountain Dew in his coat pocket. So technically, this wasn't even really a firearms-related bit of racism--it was just outright racism, and the "gun" story was an excuse for some rogue cops to get their 'roid-rage jollies...
Interestingly enough, his mother and friends all said he didn't even LIKE Mountain Dew, and was never known to drink it, and the alleged bottle was never entered as evidence...
This kid was an Honor Student at CAPA-HS, dressed nicely, and minding his own business. Reportedly, the officers never identified themselves, or displayed credentials until AFTER the EMS folks showed up. The pictures of this young mans injuries at the hands of PPD are seriously disturbing--they really let him have it:
http://www.post-gazette.com/pg/10027/1031317-53.stm
So is it safe for a YBM to OC in Pittsburgh? I guess that depends. If you live in a "bad" neighborhood, you'll probably be harassed. If you are walking in a "good" neighborhood, you'll be viewed as suspicious. If you're dressed like a hoodrat, you WILL be targeted by LE. If you're dressed like a businessman, you'll probably be seen as "uppity" by some LEOs.
I do not envy your situation. Unfortunately, Jim Crow is alive and well in many urban areas in the US, and there are MANY LEOs--of ALL races--that view any BMWAG as a serious threat.
Know the law. Assert your rights. Be polite. Carry a recorder.
And good luck!
Keep us posted...