Is it equally difficult to rack the gun's slide with an unfired cartridge in its chamber, and also with its chamber empty?
My bet is that it's easy enough to rack the slide on an empty chamber, but difficult to do so when an unfired cartridge is present.
The Buckmark is, I believe, set up to be an accurate pistol.
Part of accomplishing that with rimfire ammunition is keeping its chamber and slide-rails tight (as in +0, -0.001).
(Of course, its barrel may be dirty, or even ringed just ahead of its chamber, but a gunsmith should've seen that and reported it to you.)
There are a couple of things that you can do about this.
• Use better-quality ammunition, probably of match quality if you can find it, so you won't experience misfires,
• Or you could have the pistol's chamber polished by a really good pistolsmith. (Don't do it yourself.)
• You might also have the gunsmith polish the pistol's rails, both of the slide and of the receiver.
If your pistol is brand new, you may merely be experiencing tightness that has not been worked out yet. Some pistols need a break-in period.