Need help sizing rear aperture and front sight post

[BobN54]

I need some help selecting the front post and rear sight aperture dimensions for NRA - DCM High Power service rifle competition. It's for a Bushmaster DCM-XR rifle I'm purchasing for my son under their junior shooter promotion. He is a beginner, and is progressing well. Bushmaster offers a choice of: 036", .040" , .046" , or .052" diameter aperture for rear sight. The Competition Front Sight, ground on three sides, is available in two widths .052", or .062". What factor's influence the choices and what is recommended for shooting out to 600 yds?

[dennymac]

Good afternoon. I am a firm believer in having enough light to do the job at hand. In this instance we are trying to see a 13 inch diameter black at 200 yards. I have found that as the years creep past I have needed larger rear apertures to see the aiming bull clearly. I am currently using a .040 rear aperture. One of the teaching axioms that we use here in KY is 'the pumpkin on a post' for the 6 o'clock hold sight picture. In High Power lingo, this is using a front sight that appears to be the same width as the aiming black. It allows the shooter to have a good visual reference that he is well centered on the target. Once again, as I have aged, I have come to prefer the 'apple on a barrel' approach. I use a front post that looks wider than the aiming black. This actually allows me to use a bit of 'Kentucky windage' to allow for drifting the bullet into the black instead of adjusting the sights. It especially helps during the rapid fire portions of the match. I recommend that the junior shooter start with a .040 rear sight and the .052 for the front. As with all advice, your mileage may vary. Best of luck to you and your son. DennyMac

[BobN54]

Thanks Dennymac, your rationale helps a lot!