Questions re: NIB M640 Pro care-and-feeding

Absent any factory defects/flaws, it sounds like you just have carbon build up on the face of the cylinder/face of barrel and maybe some firing residue in a couple other places. Look for that the next time you shoot it if it starts binding again.
You can measure the barrel/cylinder gap with feeler gages. It might be a bit tight. Measure with the cylinder pressed all the way to the rear, then put some spent cases in the chamber and remeasure. I usually measure twice without cases with the cylinder pressed to the rear and then to the front. I repeat with spent rounds or headspace gages in the chambers. I am checking for two/sometimes three things - end shake, barrel/cylinder gap, and sometimes headspace.
If the barrel/cylinder gap is too tight the back of the barrel can be faced with the proper tools. Do not do it by hand with a file.
Do not be taking off the side plate unless you really need to get to something for repair or tuning (if you do remove it there is only one right way to do it without damaging the frame and/or side plate). Ask here if you really need to do that. If you decide you need to get that deep into the gun best to have a copy of Kuhnhausen's S&W Revolver book in hand.
Flush with Gun Scrubber or other cleaner through the opening under the grips, the cylinder bolt hole, and cylinder stop hole. Flood it, let it drain, then oil it.
Dry fire won't hurt it, but snap caps are always a good idea.

Sounds like you are shooting some crummy ammo? What brand is it? Did you shoot 357 mag or 38 special?????

Yes you can dry fire any SW centerfire revolver, no it will not hurt it. If you still have trouble, and the gun is new CALL SW and return it. You should not have to mess with cylinder gap or any sort of related issue
No, you should almost NEVER have to open the side plate!
Test it with ammo you intend to carry.

If the gun is really tight check for powder residue under the ejector. I have a Colt python that the cylinder will get hard to open/close if residue gets under the ejector.

rickr44318 said:

I might look for Kuhnhausen to have the knowledge...

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Even if you never do a thing to the gun, this book is great to have around to enable you to understand what is happening. More knowledge is always a good thing.

rickr44318 said:

Thanks, all, for your feedback.

Yes, I'll be taking it back out with some U.S.-made ammunition, including my carry JHP (the stuff I fired on Wednesday was .38 Spl ball, just to get a feel for the weapon; as I say, the Hungarian rounds were noticeably dirtier).

I might look for Kuhnhausen to have the knowledge, but I don't have the tools or the inclination to try and really smith this item, so I'm glad not to have to. As long as it performs when I clean it, I'll be happy. I may touch base with S&W just to get their take.

Best to all in the New Year!

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You don't need the book (other than just for "education" A new gun you should not do anything to it. Let SW take care of it. It doesn't cost you anything other than some time away from it.