100 yard sights

[jonniereb]

I remember seeing on the bulletin board several years ago a formula for determining how far to raise your rear sight at 100 yards on a musket sighted for 50 yards. I wish I had printed it off then! Does anyone know what I'm referring to? I ask because someone gave me a trick to use for raising the rear sight if you don't need to go up a whole step on your factory sight. They suggested using a set of spark plug gap measurement tools as shims. So I got a set that came on a keychain so I could remove them individually. Problem is, I don't know which thickness to use. Then I remembered reading about that formula from way back.

Sooooo... if I'm sighted in at a dead center hold at 50 yards, and I shoot 40 grains of 3F with a Rapine ashcan sized to .576, and wind and light and all other variables being equal, and Train A leaves Chicago traveling 48 miles per hour, how far do I need to raise my rear sight (in thousandths of an inch) for a dead center hold at 100 yards?????

Thanks in advance...

[jonniereb]

Got my answer via PM. That was fast! Thanks!!

[Greg Ogdan, 11444]

Jonathan,

You might want to re-think the ashcan at 100 yd. I tried EVERYTHING and never could get any accuracy due to the wreched ballistic coeficient. Finally had to go to a 510gr big minnie, Rapine 575510. Way big improvement!

[Scott Kurki, 12475]

Got my answer via PM. That was fast! Thanks!!

Please share "secret" formula with us all.

[Tom Magno, 9269V]

Train A leaves Chicago traveling 48 miles per hour.

That's a mile traveled for every 1 minute 15 seconds. No secret, just math.

Seriously, the formula is well known: sight radius/range = amount of change to move bullet strike 1", where range = 1800 for 50 yards, and 3600 for 100 yards.

[Kurt Lacko 7862]

Re: windage
by Kurt Lacko 7862 » Sat Jul 09, 2011 2:09 pm

Go to www.sdmfabricating.com and click on "sight correction calculator". I can't take credit for this one, info was provided by our adj. Tom.Kurt Lacko 7862

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