I finally got down to the point where I stained my rifle today. I tested some vinegar stain that I have had brewing for the last 3 weeks and ferric nitrate solution that I made up on some hidden areas of the stock, but wasn't satisfied with the results, so I went to Menard's and found a nice 6-foot piece of curly maple 1 x 2 for $4.19. I cut it in some 5" strips and tested both stains. I liked the results of the vinegar stain better than the ferric nitrate solution, so decided to go with the vinegar stain. I ended up diluting the vinegar stain 50:50 with water, and filtering it through a coffee filter. It had the appearance of very weak coffee.
I read earlier in this thread that you don't need to heat or flame after applying the vinegar, but the maple pieces that I had turned a bluish grey after applying the vinegar stain, so I heated it with a heat gun. It did develop some yellowish undertones when I heated it and the bluish color disappeared somewhat. However, the greyish color still concerned me somewhat, so this is what I ended up doing:
1) applied a thin coat of the vinegar stain with a brush, and let it dry. It turned a bluish grey color and the figure in the wood disappeared when the stain dried.
2) I heated the stock for about 10 minutes with a heat gun until some of the bluish color disappeared and a warmer tone developed.
3) I diluted some Laurel Mountain Forge maple stain about 1 part stain to 5 parts denatured alcohol, and put two coats of it over the vinegar stain after it had been heated.
4) I then rubbed the stock down with Tru-oil finish. It turned out a dark brown with reddish undertones, almost a aged mahogany appearance, but the figure of the maple is very apparent. It is fairly dark, but still has the "tiger-eye" appearance.
I'll try to post some pictures tomorrow after I get a couple more coats of oil finish, as it might lighten up some more, but overall I'm very happy with the results. I think it might not have turned out as dark if I had diluted the vinegar stain some more. I guess the moral of this story is to test it out on some pieces of the same type of wood and repeat the same process on the sample that you like the best.