I have a el cheapo tang peep sight on the rear and a Lyman 17 A on the front with a square post insert, on my rolling block. I prefer that to an aperature in the front because when used with a 6 o'clock hold it allows me to see the whole target and since it is too time consuming to adjust a rear sight with no click stops, it allows me to quickly compensate for wind and drop errors. I am prepared to admit that with expensive click stop rear tang sight and a setting that is nearly correct, the double aperature is more accurate but I am too cheap to spend $400 or so for the expensive tang sight
cheers mooncoon