If the gun is in good shape otherwise, you probably just need a new hand. It's easy stuff. But the problem will only get worse until at some point it will start skipping/slipping between cylinders. This is a standard wear item on revolvers. They need less gunsmith tuning than something like a 1911, but more than something like a Glock.
If you intend to shoot a substantial amount through on old K frame, investing in replacement parts now is a good idea, while they still can be found.
On one of my Security Sixes, I get unburbt powder blowback on me. Seems like it only happens worse on one cylinder. However I may be misperceiving what’s happening.
Is this a timing issue? Is there any danger !