Help! Please...sight question on my Winc. 94

[demented]

 I have a 20" barrel 94 that I installed a .340 tall fiber optic front sight with a Williams receiver sight.  The problem is that with the receiver sight adjustment all the way down, I'm shooting about four inches high @100 yds.  How can I determine whether I need to go with a .375 or taller sight to get this shooting a bit closer?  Anyone that can help with this, I'll be eternally in your debt.  I didn't think this would be an issue until last weekend, I took a shot at a deer at 80 yards from a hill thats about 30ft higher than where the deer was, ended up shooting clean over him.  I'm not that good at guessing bullet trajectory when combining shooting downhill with a rifle already shooting high.  BTW, I did get him with my second shot, he was quartering away, looking over his shoulder while trying to see where where the shot came from.  My second shot was also way high but his head got in the way....Blind hog and the finding an acorn story fits here.  Sorta messed up the rack to say the least.  Even though my hitting him was PURE luck, I'm proud of this, was my very first deer taken with a 30-30, I've always used scoped bolt actions from .308 on up to 7mm magnums. Thanks for any help, comments, etc.....

[gunnut69]

A taller front sight will move bullet impact lower on the target. To determine the height you need you must measure the height of the rear sight fromt the center of the bore. This is 1/2 the diameter of the barrel at the front of the receiver plus receiver difference above the barrel surface plus the distance from the receiver top to the center of the sight insert in the receiver sight with the slide lowered completely.. or at least nearly completely. The front sight height will be the measurement resulting from above minus 1/2 the barrel diameter at the muzzle and to the bottom of the ramp dovetail if there is a ramp. There is a aclculator in the Brownells catalog to help and there used to be one online at their website.. by using the rear site at it's lowest setting the elevation can be used to zero the rifle and keep that sight slide as low as possible for strength. If the front site is too high it may be necessary to install a ramp to keep the front site weakness down. It sounds a bit complex but its' really not.. The bore is the starting point for measurements..