You might consider using an adjustable aperture disk like the Merit (
http://www.meritcorporation.com/products.html) which allows you to adjust for light conditions while actually looking through the sights. An old target shooter's trick is to use the disk to bring the front sight in focus. As you no doubt remember from your Marine training, you want the front sight to be in focus, while the target presents a gray outline.
You also might want to swap your bead front sight for a Sourdough type, which offers a flat aiming surface. Along with other Marine Corps team shooters, I preferred the "Navy hold", which is to say that the sight is aligned with the center of the target, rather than the "pumpkin on a fence post" or "six o'clock" hold, which requires the shooter to align his front sight with the bottom of the black aiming circle and adjust the sights so they strike in the middle of the black.
These sight blades were made by Redfield and are still sometimes available at sites like eBay. The nomenclature for the correct sight
blade to go with your Lyman 48 receiver sight is "Redfield 21-S Front Blade Sight 1/16" SOURDOUGH PATRIDGE Bead .430 Height".
