very concise, well thought out overview. it's clear that you've put a lot of thought into the parts you've selected. some of the cons go without saying.
the 'requires a bent bolt' con for example is a common problem with trying to mount a scope on military surplus rifles. anyone that looks at a straight bolt in the open position can see that it just wont clear a scope mount. it is interesting though that even the RSI bent bolt system couldn't completely clear the mount though, you would think that they would design both parts to have at least a centimeter or 2 of clearance.
one question. can you still use stripper clips with the RSI mount? that may be another for the cons section.
the 'must inlet stock con for the bent bolt' is another common problem with bent bolts on military surplus rifles. this is evident in the US 1903A4 sniper rifles as the standard bent bolts still could not clear the scope mount so they had to curve them into a semi circle angled up and then bend down which required the stocks to be inletted. the Mosin nagant and german snipers tried to fix the problem of having to inlet by mounting unusually high scope rails that allowed the conventional(in the mosin nagant's case PU bolts) bent bolts to clear but the side effect of that was that there is no decent way to get a cheek weld because of how high the scopes rest. the only rifle to solve both problems that I know of is the british enfield 'T' snipers that still used the standard bent bolts and did have a high scope mount but instead attached cheek rests onto the buttstocks to raise the shooters cheek weld up to a comfortable level with the scope.
my personal experience with the boyds thumbhole was a bit different. I had to do some work with a dremel to get the stock to fit my 91/30. not all of these rifles and stocks are built exactly the same every time so there will be some like yours that drop right in and there will be others like mine that need some fitting. the not good for lefties is just a problem in general with thumbhole stocks. my lefty friends hate when I bring my 9130 because the only way they can shoot is by trying to get their thumb over the tang instead of through the hold and the cheek rest is just not comfortable to use. I don't know if boyds makes them or not but there are some left handed thumbhole stocks out there but they have the same problem, righties cant use them.
EDIT: Duzell, I think he means that he just introduced one, check out the link in his sig line.
ignore my complete lack of capitalization. I still have no problem correcting your grammar.
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