Of course these may be due to simply a bit of sloppy re-assembly after cleaning or maintenance and the grips may not be ill-fitting at all. This is actually what I suspect we see here.
Its a shame the guns were recoated for the NRA loan. Just a hideous attempt all around. Much of the original finish was carelessly removed by improper moulding for the film so the other was toned down to match. Thats why both live fire guns look so much brighter in the film than they did in the series. Poor guns cant get a break even in retirement. For an idea of how terribly done that refinish is, this is one of the live fires next to my Phil casting after production wrapped on the film as compared to the white glove NRA picture posted prior.
As the two live fires were in the process of being modified for the film I can tell you the fitting of every single part was clanky and wobbly including the grips. After the modifications and complete tear down and reassembly, they were battle worthy. As per the grips, even after the rebuild they were what they were as they were filed down by hand to fit, just as real world western guns were.
I have found that electro-plating can be done at home. You can get the electrolyte chemicals and brass anodes by mail order and do it yourself, or you can buy a kit like this;
http://gaterosplating.co.uk/Brass-Plating-Kit.php
Just hook up a 12 volt power supply such as a car battery or (as I intend to do) the mains transformer off your kids train set and off you go. There are even helpful video tutorials for the kits on YouTube. I'm sure you can get similar kits in the states.