[Lurch1962]

JAMF, and NonWonderDog,
Do be aware that running an incandescent lamp at half voltage results in 1/4 intensity. Also, the color temperature changes noticeably, becoming redder. Such a filament-based lamp when operated nominally already has a low enough temperature to have its peak emission in the invisible near-IR. At 1/4 power output the peak not only drops in intensity, but moves a bit farther into the IR, which is what results in that light which is visible appearing redder.

The above notwithstanding, I'd think that a gun sight lamp would be driven at a higher-than-otherwise-desirable voltage so as to maximize reticle visibility but not result in a lamp life shorter than, say, several hours. In such conditions the filament will certainly be a more whitish-yellow than orange. Buttressing this supposition of mine is the fact that pilots seemed to be always concerned with lamp burn-out, and always had a few spares in the cockpit.

So, my recommendation is to go back to the yellower color.