Buckmarks are awesome.
Simple. Accurate. Reliable.
I have two.
One of them is sitting at about 132,000 rounds, and has never suffered breakage of any kind. I've replaced a few springs and buffers as maintenance items, and changed a few screws from slotted (old style) to hex ('new'-style); but that's it.
The other is around 80k-90k rounds. It broke a firing pin. Right now, I can't remember what I figure that round count was, but I think it was around 18k-20k. Regardless, the firing pin was broken for another 2k-3k rounds, before it got replaced. The pistol still functioned as intended, even with the broken firing pin.
Browning originally suggested removing the top strap, barrel, and slide for cleaning, so that's what I do. When I clean it, I tear them down.
But, they changed their recommendations when they went to the new style slide and firing pin block (circa 1999?), to just "open the slide and get what you can see".
So, you'll see people claiming both ways are correct. Both are wrong and both are correct. Different strokes for different folks (and time periods).
Since I do disassemble mine for cleaning, I keep a supply of washers and screws on hand. I've never lost a screw, but I torque the crap out of mine, so the hex socket does get slightly deformed over time. I replace them before it becomes an issue.
Oh... Another note on cleaning:
Buckmark magazines don't require much attention, but do benefit from occasional cleaning. I still have the original magazines for both pistols, plus some extras - the newest of which is from when the Buckmark rifle was released (2000?).
One of the original magazines had feeding issues and seemed like it was finally time to replace the spring. I ordered springs and tore the magazine apart, only to find that it needed nothing more than a good cleaning. They had occasionally been swabbed before, but never disassembled for cleaning.
A proper cleaning is all that magazine needed. But I do have some spare springs, now...
There should be no issues with choosing one grip frame over another. But if you think you may want to change grip panels at some point, it would be worth checking to see if what you want is available for the grip style you're looking at.
One benefit of the Buckmark, versus the Ruger Mk series (and 22/45), is that the grip frame is the serialized part. You can swap barrels to your heart's content, and it's no big deal.
The Rugers are the opposite, however. The receiver is the serialized part. So each "barrel" is actually the firearm. Shipment, transfers, possession, and storage of Ruger Mk and 22/45 'barrels' needs to be handled like any other firearm.
A downside to the Buckmark is that integrally suppressed barrels are less common and generally more expensive than those available for the Rugers. If you want to use integrally-suppressed barrels, the Rugers are the better option. If you want to use suppressors and don't mind screwing one on to a threaded barrel, the Buckmark options are still more limited but there's plenty available.
If you don't want to deal with suppressors, then it doesn't matter.
