Aye, very much been there done that. But there are a whole host of things which ultimately contribute to accuracy. The reason I tend to find bolties somewhat infuriating is you can get them shooting absolutely perfect, and then everytime you take them apart to do maintainence (and you should at the very least be properly cleaning the barrel after every outing imo) chances are it won't be as perfect as it was.
Just the nature of the platform, everything needs to be well lubed and clean to get that consistency... but to ensure everything is well lubed and cleaned you have to take them apart alot. It's a weird vicious cycle, I'm sure many would echo the frustration of having your RIF shooting exactly as you want and knowing you need to tear it down at some point... and be forever be chasing 'how it was' ?.
Just looks like a bit of 'flash' from the moulding process, wouldn't be enough to disrupt anything imo... largely because it looks to be on the bottom edge of the piston cup. It's hard to say really, given they're made in batches and seem to iterate on the design/manufacturing of components for each run outside of general advice of what usually works it's difficult to provide much else.
Given yours is from the most recent batch I'd say the best bet if none of the standard stuff seems to be working would be to jump into a SRS Facebook group and see what other owners of RIFs from the same batch have to say. They'll likely wind up asking exact what parts are in there, so brace yourself for the irritation of having to explain that it's irrelevant what hop chamber you're using because the leak seems to be from the cylinder/piston. I don't tend to advise anyone toward Facebook groups (outside of the Wolverine MTW Owners group because the folks in there are genuinely helpful regarding that platform), but I'm not sure how useful historical/general information on prior models of the SRS is at this point.
