as long as the "workings" of the bolt arent compromised, then why not?
I dont see it as being a highly effective way to lower the overall weight of your rifle, but it would be considered an asthetic modification that would turn a few heads.
A rel way to reduce the weight of a rifle is to use compostite stocks, fluted barrels, shorter barrels and high grade metals ..IE: titanium.
BUt another consideration is that the use of optics, slings, bipods and whatever else you can think of, may negate the weight loss. If your only talking about a few ounces it may be more headache than reward.
And truely.. If I was to close my eyes, I wouldnt be able to tell you if I was holding my rifle with the bolt in or not. The weight loss from refining the bolt would be minimal.
But go ahead and do it.. then post up pics. Guys maight want to see your work and follow your lead.