View Full Version : Filing the front sight - how much?

December 9, 2001, 03:44 PM
I've got an SP101 that constitantly shoots 6-8" low. If I were to file down the front sight, how much should I take off? It seems I've seen a formula to calculate this somewhere.
Any "tricks of the trade" on the actual act of filing the sight down would be appreciated also.

December 9, 2001, 04:38 PM
I take a file along on sight in sessions..Place the file on bed of truck and work the front sight down alittle at a time by running the sight over the file..Really bad when you take off too much, go slow and easy.....

Art Eatman
December 9, 2001, 08:08 PM
Best to work at the range, with sandbags on the benchrest and a target at, say, 10 to 25 yards as you see fit.

File, shoot; file, shoot.

Remember that heavy-bullet hot loads uusally print higher than light-bullet hot loads.

:), Art

December 9, 2001, 08:16 PM
Would .357 loads normally print lower than .38 spcl?
.38's shoot close to point-of-aim, inch or two low. Best results were 148gr HBWC over 2.7gr of Bullseye.
The .357 loads, 125 & 140gr JHP & 158 gr SWC all go 6-8" low.

4V50 Gary
December 9, 2001, 09:02 PM
As a sinner, I've used the file. But the better way to do it is to have a pane of glass and emery paper. Place the emery paper on the glass and slide the front sight blade along the emery paper. Be sure that the rear sight stays on the glass. This will keep your front sight horizontal. Like Art sez, take off some metal & shoot. Take off some metal & shoot.

December 9, 2001, 11:10 PM
Faster bullet often prints lower than slower one. Faster bullet gets out of the barrel quicker and therefore muzzle rise is less.


James K
December 10, 2001, 01:05 PM
Remember that no matter what you do with the sight, it will be good only for the load you are using. Another load and you will be off again. That is the reason for adjustable sights.

With fixed sights, it is sometimes easier to find a load to match the factory sights.


Jim V
December 11, 2001, 06:36 PM
From Brownell's Gunsmith Kinks 4:

Mulitply the sight radius, in decimals by the error. Then divide the result by the distance to the target in inches to give the sight adjustment.

Example: Sight radius is 5 3/4" = 5.75"
The error is 10" low
The distance to the target is 25 feet = 300"

(5.75 *10)/300 = .19166666666666........."

One sight or the other would have to be raised or lowered the .191" to center the shots.

Now if the firearm were a pistol with tiny sights removing .191" from the front sight would have you filing off part of the slide.

December 12, 2001, 10:33 AM
Thanks Jim, that's what I was looking for. Without any accurate measurements taken it looks like I'll have to remove about .039". When the weather clears up I'll go to the range and get more precise readings.

December 15, 2001, 12:43 AM
put the gun in a vise.

Take a fairly fine file and put the uncut part of the file on the rear sight. Put thumb pressure on the file to keep it flat on the rear sight... then by moving the file side to side you will even up the top of the front sight with the rear.