another bit of "M-100 advice" is to make SURE that there is a gunsmith willing to work on the gun in your area, this is a C.Y.A. move in case something goes south, there are more parts in this things safety than many similar guns have overall! also winchester (USRAC) won't sell parts for them any more, the complexity (they've been out of production for how long? and folks are STILL find new ways one can cease to work) plus the need to "quest" for certain common parts has lead most gunsmiths i've spoken with to swear them off completely.
how do i come by this tidbit, i inherited my grandfather's M-100 in .308, prior to it's arival (knowing that some 'smiths are picky about what they work on) i checked around to see who would work on it if something went wrong. i just THOUGHT i knew what the evil eye was.....
don't get me wrong i know folks who LOVE their Wichester Mod. 100's but i think it is better to make sure you have an outlet for repair if the gun DOES break and never need that service, than to have it break and have to hunt a willing and competent smith after the fact.