Filing the front sight - how much?

Sisco · 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.

gunny6 · 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

Sisco · 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.

C.R.Sam · 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.

Sam

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

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.

Sisco · 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.

Archie · 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.

December 9, 2001, 03:44 PM	#1
Sisco Senior Member Join Date: March 25, 1999 Location: KS Posts: 1,558	Filing the front sight - how much? 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. __________________ "I don't mind it when stupid people say stupid things. Stupid people should be encouraged to say stupid things, that way we always know who the stupid people are." ~ Ted Nugent http://www.awbansunset.com/awcountdown_sm.gif

December 9, 2001, 08:16 PM	#4
Sisco Senior Member Join Date: March 25, 1999 Location: KS Posts: 1,558	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. __________________ "I don't mind it when stupid people say stupid things. Stupid people should be encouraged to say stupid things, that way we always know who the stupid people are." ~ Ted Nugent http://www.awbansunset.com/awcountdown_sm.gif

December 9, 2001, 09:02 PM	#5
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,841	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. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

December 11, 2001, 06:36 PM	#8
Jim V Senior Member Join Date: January 31, 1999 Location: SE Michigan - USA Posts: 4,038	Adjusting sight height 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. __________________ MOLON LABE* If it ain't metal, single stack & single action, it ain't a 1911 no matter what it looks like. 1911 Forum THE TUBBY CURMUDGEON

December 12, 2001, 10:33 AM	#9
Sisco Senior Member Join Date: March 25, 1999 Location: KS Posts: 1,558	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. __________________ "I don't mind it when stupid people say stupid things. Stupid people should be encouraged to say stupid things, that way we always know who the stupid people are." ~ Ted Nugent http://www.awbansunset.com/awcountdown_sm.gif

December 9, 2001, 04:38 PM	#2
gunny6 Member Join Date: April 16, 2001 Location: Central Arizona Posts: 94	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.....

December 9, 2001, 08:08 PM	#3
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	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, 11:10 PM	#6
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Faster bullet often prints lower than slower one. Faster bullet gets out of the barrel quicker and therefore muzzle rise is less. Sam

December 10, 2001, 01:05 PM	#7
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	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

December 15, 2001, 12:43 AM	#10
Archie Senior Member Join Date: May 26, 2000 Location: Hastings, Nebrasksa - the Hear Posts: 2,209	SK, for the finish.... 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. __________________ There ain't no free lunch, except Jesus. Archie Check out updated journal at http://oldmanmontgomery.wordpress.com/