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Lefty SRH
01-14-2020, 06:51 PM
I recently mounted a Lyman 66A receiver sight on my M94 30-30. I using the factory bead front sight thats either .310” or .315” (bottom of dovetail to top of bead) tall. I plan to replace the front with a Sourdough partridge but want a little shorter front in order to lower the rear. The rear is kinda high right now. The gap from the top of bolt to the underside of the windage bar is .137”
If I use a .260” tall front thats a difference of .050” from the factory (keeping it simple). Do I just adjust the lower .050” to theoretically keep the same zero I have now?

If Im wrong on this, what height front do I need to lower the rear about .050”-.060”?

1006
01-14-2020, 08:24 PM
I think you just need to go down the same amount on each sight.

pietro
01-14-2020, 08:26 PM
.

If you lower the receiver peep sight as low as you want it, then shoot it at 100yds and measure how low it shoots, you can calculate the proper height front sight needed.

After shooting:

1.Measure your Sight Radius.
2.Multiply your Sight Radius times your Impact Distance (the measurement of the POA to the POI)
3.Divide your Target Distance in inches

https://cdn2.bigcommerce.com/n-yp39j5/owcxm/product_images/uploaded_images/formula725x117.png?t=1436529433

cwtebay
01-15-2020, 12:17 PM
.

If you lower the receiver peep sight as low as you want it, then shoot it at 100yds and measure how low it shoots, you can calculate the proper height front sight needed.

After shooting:

1.Measure your Sight Radius.
2.Multiply your Sight Radius times your Impact Distance
3.Divide your Target Distance in inches

https://cdn2.bigcommerce.com/n-yp39j5/owcxm/product_images/uploaded_images/formula725x117.png?t=1436529433I've seen this formula before - but just wanted to clarify. For a 15" sight radius at 100 yards that is 2" off the mark, is it:
15"x100(12"x3')
_________________
2"
??

Thank you.

Sent from my Pixel 3 XL using Tapatalk

beshears
01-15-2020, 06:18 PM
If you come down the same front and rear zero will remain same. At 100 yds with 15 inch sight radius each .001 difference in front sight will change impact .240 inches at 100 yds. 100 x 36=3600 divided by 15=240 x .001 = .240

clodhopper
01-16-2020, 12:03 AM
If a shorter sight is needed, why not just use a file?

Lefty SRH
01-16-2020, 07:37 AM
Thanks for the help guys.
I cant and dont want to use a file. That would mess up pre-64 original parts. The original sight is a bead type. A file would ruin it.
Sure, you can file down a Sourdough Patridge but then you are reducing the size of the brass insert at the top of the blade.

Rich/WIS
01-16-2020, 12:21 PM
Confused by the 15" sight radius, would have thought the distance from front sight to rear of a receiver on a M94 would be at least 24".

Lefty SRH
01-16-2020, 02:45 PM
Its actually 22.5”
The 15” sounds like it measured to the factory buckhorn.