Sounds like you got a couple of real winners. Hold on tight to them.
Again, holding the trigger back on the S&W, and all other DA revolvers except the old Colt actions is NOT a valid test for anything.
While the cylinder may seem to lock tighter the action has designed-in backlash that will allow cylinder movement when fired.
When testing lockup and alignment, put EMPTY cases in the cylinder. Often the ejector is slightly loose and may give a false indication of locking.
There are several places to NOT learn how to work on guns:
The forums, unless you're VERY careful.
You have no way of knowing who's right and who's some kid or boob sitting in the basement and posting.
Youtube.
This is even worse. I've seen some videos that show ways guaranteed to destroy a gun.
One video showed disassembly of a Python where he recommended using pliers to remove the barrel !!!! and a screwdriver to pry off the side plate.
At the range or gun shop.
Again, they may or may not know what they're talking about, and I've heard advice that was deliberately intended for the owner to damage his gun.
What it is that causes someone to do something so vicious is a mystery to me.
What I can guarantee about bad advice is that the person giving it WILL NOT be standing by with a handful of cash offering to buy you a new gun because his advise was totally wrong.
Where you can learn is by careful picking of posters on this forum with lots of posts and where no one posts that the advice is wrong.
There may be slight disagreements among experts on fine details but not clear statements that something is just flat out wrong.
Buy the Jerry Kuhnhausen Shop Manual on the Double Action S&W Revolvers.
These manuals were written as training aids for new gunsmith students and show all repairs to FACTORY standards. You'll find no advice on heating and bending, soldering, or altering parts to get a gun working somehow.
These manuals show how to restore a gun to factory original operating condition.
Buy them from Brownell's, Midway, or direct from the publisher.
Getting admitted to a S&W armorers course.
These are usually restricted to law enforcement but sometimes ordinary people can get in.
Taking a NRA Summer Course that gives S&W training.
Almost these recommended ways to learn hold true for other guns too.
As example, if you want advice on a Colt, go to the Colt forum.