Basically the plan is, arrive in DE uncase the Saiga (.223 with 15 round mag) and throw it behind the backseat. Then continue on to Ocean City MD
Follow me here as I respond to the rest of the post so you'll understand why.
Can I keep anything loaded and uncased in the truck with me at all?
No you can't. You can have an empty unloaded long gun as long as it isn't on the MD regulated list. (Rifles on the regulated list are for all practical purposes handguns.
I heard you can open carry longguns but didn't know if it applied to vehicles or not.
You can technically open carry long guns that are lever, bolt & other non-regulated guns. However, in practice I'd not try that as individual LEOs may not be aware of that law. It actually has nothing to do with where you have it, just what it is. It is legal to have loaded magazines for unregulated rifles with you as long as:
1, Its not a regulated arm (Saigas are regulated), &
2, The magazines are in a "container" (which may be just a range bag or something similar.)
3, they are not in the rifle at all, no matter what it is.
Also don't know if they have any of the rediculious expanding ammo laws NJ suffers from.
Nope, we're better off than NJ on that point at least.
So why a bad idea? Because it is confusing & horribly open to interpretation & you better be darn sure you know every itsy-teensy-tiny bit of the law before you get tagged for a detail.
For example an AR-15 standard barrel IS regulated, an AR-15 Target HB is not.
I have a Lee-Enfield, its non regulated. I have with me in a car (or in my pocket) a magazine with 10 rounds of .303 British hollow point ammunition. Is it legal?
Can I guarantee you that a MD state trooper won't pull you over for "brandishing" & that you won't have the rifle confiscated, be arrested & have to go to court to get it back?
Example 2: I have a FN-FAL semi-auto in .308 Winchester. I have a reduced capacity 10-round magazine of .308 FMJ amo, again seperate & in a pocket. Legal?
Nope its a pistol.
(at least legally it is even though it obviously isn't in the real world.)
Hope this helps a bit.