A couple of things to check here.
First, what trigger are you using? However not likely to be the cause, there's definitely potential here.
Second, have you cleaned the firing pin assembly? Some people will clean all of the grease out of actions that we ship them with and this is a bad practice. We lubricate areas that need lubrication when they go out the door and advise you keep them that way. If you haven't already, try adding some lubrication on the firing pin shaft and inside of the shroud. We've had some (very few) of these RimX firing pin assemblies gall between the shaft and shroud. We made a change on the treatment of the shaft and are now nitriding them to create a thicker, harder case on the shaft. Most of the original treated shafts have been performing perfectly fine and I wouldn't be concerned about the potential for light strikes if you haven't encountered them at this point. The way to tell if you have an original shaft or a nitrided shaft is the color. Originals will be blue and nitrided will be black.
Third, check the head space on the barrel. Again, not likely to be the cause, but still potential. Remove the extractor first (1/16" Allen wrench) and use the supplied no-go gauge to verify there isn't excessive head space.
If all of this leads you to the same result, please reach out to us and allow us to work through this with you.
Thank you - Ray
keystoneaccuracy.com
Reminds me of a small bore cannon LOL. I think you will really like that Nevius chamber. Mine chambers like butter, at first I thought that it wasn't chambering a round, looked and there it was! 
