usual sight height at 25yards

[vhince524]

what usually is the front and rear sight height for 1911 govt models if you are zeroing them at 25yards (6'oclock) using factory 230grain fmj?..... :confused:

[Dave Berryhill]

It varies from pistol to pistol but I've found that on a Government Model with factory sights (standard dovetail rear, staked front sight) that the difference in height between the two sights is around .150. In other words, if your rear sight is .315 tall, the front sight will be .165.

It's not exact but it should put you close. If you're going to change the sights on a pistol and it's currently shooting to point of aim then you can measure the current sights, subtract the difference and use that number to calculate the height of your new sights.

There are a number of ways to measure the height of the sights. On my numbers above I've used the height of the actual sights but you can measure the height of the front and rear from the top of the slide, from the bottom or the slide, from the center of the bore, etc. It doesn't matter as long as you use the same method with the old sights and the new sights.

[vhince524]

thanks dave..... Im saving and printing this post for future reference... valuable info coming from an expert... BTW... love your replica of the MEU-SOC.... :)

[Dave Berryhill]

Thanks! Measuring the height of the sights is not as easy when you've got aftermarket sights like a Novak rear and a dovetail front sight but the concept is the same. Measure the old and new sights from the same reference point, such as the top or the bottom of the slide. If your existing sights don't shoot to point of aim, you can also calculate the amount of change necessary with the replacement sights to correct that. There is a formula posted here somewhere and Brownells also has it on their website.

[vhince524]

Dave, I measured the height of my front and rear sights (Reference point is the top of the slide), and they are as follows... BTW, they're Ed Brown fixed front and rear sights...

front: .202"

rear: .246"

so in order to have about .150" difference between them. I'd have to file .106" from the front sight and it would be reduced to .096", thus the difference between the rear and front sight would be .150" correct?

[niemi24s]

Before taking a file to your front sight, keep in mind lowering the front sight by 0.106 inch will (in theory) raise the point of impact at 25 yards by nearly 15 inches. Does the gun now shoot about 15 inches low at 25 yards?

If you haven't yet shot it with the new (presumably new) sights to see where it actually shoots, I'd strongly recommend doing that first and then - and only then - file down the front sight until it shoots where you want it to shoot at whatever range you want. Use the math as a guide in filing. It's easy to file off metal but kind of hard to file it back on!

[Dave Berryhill]

Dave, I measured the height of my front and rear sights (Reference point is the top of the slide)....so in order to have about .150" difference between them. I'd have to file .106" from the front sight and it would be reduced to .096", thus the difference between the rear and front sight would be .150" correct?

No, that .150 figure that I gave is from measuring the total height of the rear sight (from the bottom of the dovetail to the top of the sight) and the front sight blade (from the slide to the top of the blade) and subtracting the difference. It's for Government Models with standard rear dovetail sights and stake-in tenon front sights.

Measuring from the top of the slide, bottom of the slide or any other reference point is helpful if you are changing sights. In your case the difference in height between your sights is .044. If you wanted to change your sights to a different style and your pistol is shooting to your point of aim (point of aim = point of impact) then you'd want to replace it with sights that have a difference in height of .044 when measured from the top of the slide.

What are you trying to accomplish?

[vhince524]

Oh I see... First, I would like to clarify that the pair of ED Brown sight that I was referring to are already aftermarket and not what was originally installed in my norinco 1911.....What I was tring to accomplish was to determine why my POI was low from POA.... about 5". I again measured the rear sight from the bottom of the dovetail, like what you said... the caliper registered .342". Now, with reference to the front sight having .202" the difference is .140" almost at the .150" that you said which should be the difference between the two sights for it to zero at 25yards..... having that result, should I file off the .010 from the front sight to make the .150" difference? would it make a signifant difference at 25yards?

[Dave Berryhill]

Forget about the .150 difference in height! It's only applicable to standard sights and even then, it's just an average measurement that I've come up with after measuring lots of different pistols. You don't have standard sights. Your pistol probably has a Novak rear and a dovetail front sight.

To calculate the sight correction you need, use the following formula:
(error at target) x (sight radius)/(distance to target) All measurements must be in inches.

For example: If your pistol is shooting 5 inches low at 25 yards. 5" is the error, sight radius is 6.5" (the distance from the rear of the front sight to the rear of the rear sight) and the distance to the target is 900 inches (25 x 36 inches)
5x6.5/900 = .036. You need a sight correction of .036.

Sight adjustment works like this: you can move the rear sight in the same direction that you want your bullets to move (raise the rear sight and the POI moves up), you can move the front sight in the opposite direction that you want the bullets to move (lower the front sight and the POI moves up) or you can do a combination of both.

Since you can't raise your rear sight, you'll need to shorten your front sight by about .036. If you are a relatively new shooter, I would suggest that you have an experienced shooter try your pistol first or at least get some practice with it before making any permanent changes to the sights. It's common for shooters to unconsciously push the muzzle down when shooting due to their anticipating the recoil. You may find that your problem is a shooter error, not a sight error and you'll have to replace your front sight if you shortened it.

[niemi24s]

Hi Vhince524: Please pay close attention to the sage advice Dave Berryhill gave in the last paragraph of his last post and let other experienced shooters try your gun. If possible, try their guns too. This way you'll have complete information needed to decide why your gun shoots low. For instance:

1. If everybody shoots 5" low with your gun and their guns shoot OK for you, then there's no doubt your front sight needs lowering. Lower it half of what the math tells you, and try again. Still low? More math, then file off half of the new math result. Keep this up until it's OK.

2. However, if everybody shoots OK with your gun and their guns shoot 5" low for you, then the problem's no doubt your shooting style - not your gun. Now you must decide whether to change your shooting style, change the gun or do a little of both. Shooting style is awfully difficult to assess here in cyberspace - best done by somebody there when you're shooting. Cheers

[Dave Berryhill]

...Lower it half of what the math tells you, and try again. Still low? More math, then file off half of the new math result. Keep this up until it's OK....

This is also excellent advice. The math calculations are theoretical only. Once you remove material from a sight, it's difficult to replace it.

[vhince524]

thanks for your valuable inputs niemi and dave. I've been around guns for a long time but only now have I immersed in the 1911... most of the guns I owned were stock.. (glock, cz...). and have been contented with their stock sights. Now that I have grown to love the 1911.... I also realized you need to devote a lot of time in making them in accordance with your taste and I love the adventure...

going back to our topic... I let my RO friend try out my 1911 and his first reaction was... your trigger is d@#n heavy!..... then I tried making a very controlled precision shot at 12 yards on a rest... and to my surprise I was able to almost hit the bullseye... just an inch of center to the right... Im beginning to think that the main problem is the trigger... gonna try to have a trigger job and I'll update you... thank you again for your help... keep you posted

[edmorales]

It varies from pistol to pistol but I've found that on a Government Model with factory sights (standard dovetail rear, staked front sight) that the difference in height between the two sights is around .150. In other words, if your rear sight is .315 tall, the front sight will be .165.

It's not exact but it should put you close. If you're going to change the sights on a pistol and it's currently shooting to point of aim then you can measure the current sights, subtract the difference and use that number to calculate the height of your new sights.

There are a number of ways to measure the height of the sights. On my numbers above I've used the height of the actual sights but you can measure the height of the front and rear from the top of the slide, from the bottom or the slide, from the center of the bore, etc. It doesn't matter as long as you use the same method with the old sights and the new sights.

dave,
please correct me if i'm wrong. is .150 equal to 3.81 mm?
ed

[vhince524]

from a metric conversion sight, it says......"TO CONVERT TO MILLIMETERS; MULTIPLY INCHES X 25.4".... Hope it helps..... :)

[Dave Berryhill]

That is correct. .150 inch = 3.81 mm
Here is a great site that lets you convert just about any measurement into any other measurement:
http://www.onlineconversion.com/

[edmorales]

vhince, dave,
thanks. this is because my measuring tools (dial gauges and verniers) are all metric.