Over the Thanksgiving holiday my grandfather came over and along with him he brought his old Winchester Model 100 .308 semi to give to me, a big surprise! This rifle is over 35 yrs old and still looks new, other than the missing magazine. So my question is where can I get another mag., this model has been discontinued and I can't find one anywhere. And does anyone know how to break this model down for cleaning? Also does anyone have any exprience with this model, were they any good? Thanks.

I received one as a hand-me-down from my father.  Mine was pretty much as new as well.  They are a neat little rifle.  There is a recall on firing pins though, should be done for free.  Does yours have checkering or the "basket weave"?  Magazines are hard to come by, but as fortune has it:
www.ar15.com/forums/topic.html?b=7&f=92&t=148030

There is a company called Twin Pines Armory out of, I believe, Chehalis, Washington. A few years back, they bought the machinery from Winchester and began making replacement Model 88 and Model 100 magazines. They are identical in every way to the Winchester factory magazines with the exception of not having the Winchester trademark on the floor plate. These are often sold by various magazine dealers in Gun List and by Numrich Arms/Gun Parts Corporation.

895-100-100  .308 Win. 100 Magazine $52.15

Brownells has them...

www.brownells.com/index.html    
 
 

$46.94 w/dealer discount