There's a few that have failed the testing, and get rejected. Usually it's because the distributor sent a randomly chosen gun that happened to be a lemon. The KelTec P-32 got rejected but it's supposed to be decent.
If it's considered a model addition, they don't bother to test it.
What if they're all over charged? Pressure will still be too high. Unless you know for sure what sort of powder it is, it's a risk. I don't have that kind of luck.
Joe's Shooting World near Delta, PA can take your guns that aren't legal in MD.
MD legal items can be consigned. Cooter's in Forest Hill charges 15%.
Both of these guys are decent to work with.
My LCP II went back to Ruger to have the magazine release replaced. Mags were dropping when it was fired. I think the original was plastic - new one is metal.
LEO trade-ins tend to be cosmetically challenged from holster wear, but have been shot very little. And some of them are nearly perfect. Departments rotate out all of their guns at once, even the ones that weren't issued. So night sights will be dim but mechanicals will usually be fine.
How about a Halcyon? 3.41" in "compact" mode. Appears to be in stock as well.
https://www.silencershop.com/silencers/rimfire/advanced-armament-halcyon.html
TECHNICAL SPECIFICATIONS:
Weight: 6.4 oz full, 4.5 oz compact
Length: 5.8” full, 3.41” compact
Diameter: 1.0”
Materials: 17-4PH T6...