As a MD citizen with zero qualifications to offer legal advice, I can say this much - if you have your gun and your ammo under lock separately, you should okay in MD.
Even if you do get pulled over, there should be no reason to search you. (Unless, of course you give them one.)
A year ago after a Memorial Weekend From Hell, I was driving my family back from VA. Our old van broke down in Waldorf on the way down and I was forced to buy a new vehicle.
We left VA early Monday morning and crossed the Bay Bridge about 10AM. Just across the bridge I was pulled over by a MD State leo. He ran my plates and they didn't match. (Well, duh)
I explained to him what happened and showed him the paperwork. He then proceed to ask me a bunch of questions.
Had I been drinking? (10 AM mind you. I don't drive after one beer.)
Was I carrying any drugs?
Did I have any firearms?
There may have been more, but the 3rd degree was getting tiresome.
I was polite and answered his questions.
After which, he warned me to get my paperwork straightened out an let me proceed.
I didn't bother to inform him that my paperwork was just fine, thank you and it was the MVA that was lagging behind. (I bought the car through a dealer so I was certain it was all in order.)
Needless to say, if I had answered yes to any of the above questions, I would have been detained and searched.
My biggest complaint is I felt he had no right to question me about potentially illegal activities without a Miranda warning. I was wrong.
I looked it up and apparently this area is, at best, gray. At worst, a leo may ask anything without any Miranda as long as one is not in custody.
That said, I have found nothing suggesting one must volunteer any information just because someone asks. As a matter of fact, Miranda or not, I do believe the 5th Amendment still applies here.
Additionally, I have never once uncovered information suggesting one must inform any authority that one is invoking his/her 5th Amendment rights or one refuses to answer per se. To me, this would just invite a search.
As far as MD State Police are concerned, I've had contact with more than one and, like any other group, there are all kinds. One coached my daughter's t-ball team and I consider him a fine person.
That said, I think the overall culture in MD leans toward the attitude of the person with the MSP you talked to. Here are a couple of examples:
First our current governor bragging about mapping permit holders:
http://www.mdshooters.com/showthread.php?t=15643
Now here is a MD delegate (speaking) before the Handgun Permit Review Board. Pay attention to the expression on the board (bored?) member's face as the Delegate is speaking. Not to mention his final comments.
http://www.mdshooters.com/showthread.php?t=44987
What I was looking for was one man's detail on applying for a permit. At least one MSP officer was on his side but support for his attempt was not strong.
Andy