Thread: open sights

random question....what is the formula/rule of thumb for adjustment of open sights...eg 1mm=20cm at 100 meters or is it dependent on sight radius ???

Yep depends on distance between front and rear sights. Robbie Tiffen could quote the formula off the top of his head.

There is a formula in this link
https://www.africanhuntinggazette.co...tment-formula/

Yes, depends fundamentally on sight radius.

To a lesser extent it also depends on the thread pitch of the screws / sight post involved (if there are any moveable components involved in the sights).

It is pretty simple to work it all out in Excel or similar. Just convert everything to the same unit of measure.

1 MOA is an angle of 1.047 inches over a distance of 100 yards (3600 inches).

The same goes for machining an angle into a rail. The length of the rail is effectively the "sight radius".

PM me what you need and I'll be happy to double/sanity check on it

LOL that formula is roughly spot on for what I want.....and appears rounded figures and cross units to be 30" barrel sight radius slightly less 1mm adjust ment=1" of change in poi

so my old shotgun which now had 45/70 insert ....fitted norinco battle sight off the old 7.62x39mm its same sight picture as lee enfield,big block with 1.5mm wide and deep square out of top centre with line running up face to it...and brass shotgun bead......was shooting ABOUT 10" high at 35 yards
just managed to get threaded grub headed screw (out of shitty scope rings that I gave to RUMPY to get undone before I took angle grinder to them) into beads hole with a little GENTLE persuasion (started screw,backed out half turn,in three quarters over n again till desired depth was achieved)which has lifted front by 7mm or thereabouts.
so nothing moveable..but everything fileable as last resort......will have to touch off a few more rounds and see how close she is now.
thank you both for help.....

Is that 1mm of adjustment vertical, or on a ramp ?

neither...I screwed in a taller front screw....eyetrometer says its 7-8mm taller than the stumpy wee bead it replaced. I have about 4-5mm I can file down rear if need be...but hope not to have to....dont want to touch it as have tried before and didnt end up as good as originally was.
never realized the WAY sights on SMLE were intended to be used...eg you sat target ONTOP of bead in notch.....think the trick cullers used was have ramp set on 200 and put top of rear along belly line..... Im hopeing to end up no more than 3" high at fifty yards which HOPEFULLY looking at trajectory curve will be good to 130 ish,cant see me ever using my hefalump gun that far,but would be nice to KNOW approximately where big lump of lead will be landing.90% of my bush stalking shots are under 50 yards so usable at 50 will be end goal....not having to aim off would be perfection itself.

and looking at formula again my sight radius is much longer so any adjustment will be....less

Originally Posted by Micky Duck

neither...I screwed in a taller front screw....eyetrometer says its 7-8mm taller than the stumpy wee bead it replaced. I have about 4-5mm I can file down rear if need be...but hope not to have to....dont want to touch it as have tried before and didnt end up as good as originally was.
never realized the WAY sights on SMLE were intended to be used...eg you sat target ONTOP of bead in notch.....think the trick cullers used was have ramp set on 200 and put top of rear along belly line..... Im hopeing to end up no more than 3" high at fifty yards which HOPEFULLY looking at trajectory curve will be good to 130 ish,cant see me ever using my hefalump gun that far,but would be nice to KNOW approximately where big lump of lead will be landing.90% of my bush stalking shots are under 50 yards so usable at 50 will be end goal....not having to aim off would be perfection itself.

I had my 44 mag zeroed at 100 with subs. This was a mistake as it was too easy to shoot over animals. 60 metres has worked out far better and a little hold over at 100. As the trajectory is the same as a 22 with subs I sight it the same, and the 22 makes for good practice.

SHOULD be 1600 fps with smokeless45grns of 2208.......HRBP????? who knows LOL...
agree bead front and V rear works well.....however I have fitted rear sight that is VERY similar to whats on SMLE....a rectangular block with square notch out of top dead centre,with line up front face...the screw I replaced bead with fills this quite well...HOPEFULLY the extra 7mm it added will drop POI by about 7"
will have to try it and see...I have wiggle room as can drop rear by filing it down...or indeed V notching it instead.

well it worked...pretty much spot on at 50 yards..was couple inches to left...moved rear across and bingo....didnt fire enough to group et...was shooting at spray painted dot on clay pile during smoko break LOL.... but 4 rounds was enough to know its going to work just fine n dandy at that range.minute of milk bottle anyway.