As was previously said steel is not proper on such a rifle. However, you have what you have. Another option would be a gun metal gray. To do that, you need to polish the parts to 600 grit. Any less and they will rust and pit too much. Then you clean them good in Dawn detergent and don't touch them with your bare hands afterward. Next get some cold blue and tincture of iodine ready. You have going to apply the cold blue and then apply the tincture of iodine which while the blue is still wet. You should first get a nice blue from the cold blue, then it will turn black and then brown. You should get some light rust overnight. Polish off the rust with some green or lt gray Scotchbrite pads to remove the rust but leave the gray surface underneath. Don't scrub too much. You should probably start with the lt gray Scotchbrite and proceed to the green only if the lt gray isn't removing the rust. If you have done everything right, you should have a nice mottled gray surface. This is one way to age bright steel or iron.
Then again, a good even brown might be easier to achieve.
