Sight Height??

[deadin]

Anybody know how to calculate front sight height?
I picked up two Webleys today. One is a Mark IV .38, war finish, no import marks. Pretty decent shape but with a broken finger on the extractor star. (I’ve a replacement on order..)
The other is a Mark VI that has been whizzed to .45ACP and has had the barrel chopped to 3 ¼”. I bought it as a parts gun, but it’s in OK condition except for the missing front sight. I can mill a slot for the sight without much difficulty but I have no idea how to judge the height. (I suppose I could just start really tall and whittle it down until it finds paper…)
I got the pair for $100 so I guess I can afford to put a little into them…

 

[fodder]

Sight Height Calculator | World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools - BROWNELLS

 

[deadin]

fodder,
Thanks for the link, but it won't really won't work in my case as it calculates a line of sight that is parallel to the line of bore. This is fine if the gun has adjustable sights to then allow for bullet drop and recoil rise. However I need some way to calculate for fixed sights.

I guess I may have to resort to ballistic calculator for amount of drop at a given range, but I have no way of estimating amount of barrel rise due to recoil. I'm thinking to see if I can come up with a sight height ratio from an existing gun that has both sights. (like a M1917 or such.)

 

[Jessie]

Yes, there is a formula based on a known distance shot plus the sight picture you're using(poa) and the distance between front and rear sight. My GS knows it and I will get it from him and re post.

 

[ejeli]

Once you get a starting point this site will help with the amount of correction.
e.
Sight Correction Calculations

 

[Jessie]

Ok, here it is and I hope I explain it clearly....
First convert your distance to target ( from muzzle) into inches.
Divide that into the amount in inches that shot is off from point of aim.
Multiply that number by the distance in inches from front to rear sight.
This should result in a fraction of inch number that will be the correct front sight hieght.
This formula also works for left/right corrections just to let you know how much to drift your sight if its not adjustable.
Hope this helps.
I just looked at ejeli's site above and that's it and a very convenient way to use.
One thing you can do to get the initial sight picture is glue a plastic/wood front sight blade where it will go and adjust from there. It may not last more than a shot or two, but then it doesn't need to.

 

[deadin]

That calculator looks like what I need!
I like the idea of a "temporary" sight that only needs to last long enough to find paper. (and, maybe, a group small enough to work with....)

I already have .455 dies, .45 Auto dies and the correct .455 slugs. I will cobble up something close to original MkII loads and see what happens.
I don't think I have any Auto Rim so I will need to either find some, get some half moons or make a shim and use regular .455 brass.....

I'll let you know how it turns out....

Thanks.......

 

[Cyrano]

I just now ran one end of my caliper down the bore of my Mk VI. From the top of the bore to the top of the front sight is .625". Also, from the bottom of the barrel to the top of the sight is 1.145". The barrel appears to have parallel sides back to the 3 1/2" mark so this might be a valuable dimension to know also. Hope his helps.

 

[deadin]

Cyrano, You must be clairvoyant!! I was just getting ready to post a request for someone to provide me with those very measurements..

 

[Cyrano]

Cyrano, You must be clairvoyant!! I was just getting ready to post a request for someone to provide me with those very measurements..

It might be a good idea to make the sight a little higher than these measurements. No telling what the shorter barrel is gong to do to POI. You can always file it down a little if ncessary. I sure like the Webley Mk VI, a nice shooting gun.