Help with my math please

A place to discuss non-discipline specific items, such as mental training, ammo needs, and issues regarding ISSF, USAS, and NRA

If you wish to make a donation to this forum's operation , it would be greatly appreciated.
https://www.paypal.com/paypalme/targettalk?yours=true

Moderators: pilkguns, m1963, David Levene, Spencer, Richard H

Post Reply
Shooterer
Posts: 331
Joined: Fri Aug 15, 2008 5:28 pm
Location: S.E. Wisconsin, USA

Help with my math please

Post by Shooterer »

Hello,
I have the opportunity this weekend to shoot a smallbore 100-yard offhand match (more like a frozen finger challenge shoot between friends) and I could use some ballistic help.

I will be shooting a brand-new rifle with iron sights for the first time, I will have the chance to fire the rifle at an indoor 25-yard range before the match.

Here is my question:
After putting a few rounds of Wolf Match Target (old stock 40gr @ 1050 fps) through the barrel, If I set my sights to hit 10" high at 25 yards, will I be close to center at 100 yards?

I can adjust during the shoot if my sighters are close and can see them on the paper.

Thanks,
NukeMMC
Posts: 43
Joined: Sat Feb 12, 2022 12:30 pm

Re: Help with my math please

Post by NukeMMC »

Try 6". I ran it thru Strelok Pro and it comes up with 6.1moa from 25 to 100 yds
User avatar
j-team
Posts: 1381
Joined: Mon Mar 28, 2005 2:48 am
Location: New Zealand

Re: Help with my math please

Post by j-team »

6" at 25 yards would be more like 24 MOA. Don't forget that 1 MOA at 25 yards is only about 1/4"

I agree that 6 - 8 MOA will get you from 25-100. But I'd set it to shoot 1.5 - 2" high at 25, that should put you on at 100
Martin H
Posts: 153
Joined: Fri Aug 11, 2006 2:01 am
Location: New Zealand

Re: Help with my math please

Post by Martin H »

1913 with standard barrel, 20 click sights, without sight raisers:
25 yard to 50m - Up 26 clicks
50m to 100 yards - Up 80 clicks (4 turns)

1913 with standard barrel, 20 click sights, with 16mm sight raisers:
25 yard to 50m - Up 4 clicks
50m to 100 yards - Up 80 clicks (4 turns)

Cheers Martin
Shooterer
Posts: 331
Joined: Fri Aug 15, 2008 5:28 pm
Location: S.E. Wisconsin, USA

Re: Help with my math please

Post by Shooterer »

E903A25D-6B06-46F2-AE9F-FB910345AA8F.png
E903A25D-6B06-46F2-AE9F-FB910345AA8F.png (31.08 KiB) Viewed 5449 times
Thanks for the help, I found this chart and I am going to use 6” above a bullseye at 25 yards and bank on a 6-7” drop at 100yds.

Also I attached a picture of the type of CPA rifle I am sighting in
Attachments
4906CC27-B1CB-4C8C-A6E7-FC0AD27BF446.jpeg
4906CC27-B1CB-4C8C-A6E7-FC0AD27BF446.jpeg (22.95 KiB) Viewed 5449 times
NukeMMC
Posts: 43
Joined: Sat Feb 12, 2022 12:30 pm

Re: Help with my math please

Post by NukeMMC »

Steven's 44 1/2?
Pope barrel, I assume.
User avatar
j-team
Posts: 1381
Joined: Mon Mar 28, 2005 2:48 am
Location: New Zealand

Re: Help with my math please

Post by j-team »

Shooterer wrote: Mon Nov 21, 2022 7:14 pm I am going to use 6” above a bullseye at 25 yards and bank on a 6-7” drop at 100yds.
You will be way too high. Try 2.5" high at 25 yards.
User avatar
j-team
Posts: 1381
Joined: Mon Mar 28, 2005 2:48 am
Location: New Zealand

Re: Help with my math please

Post by j-team »

See this:
Attachments
Capture.JPG
NukeMMC
Posts: 43
Joined: Sat Feb 12, 2022 12:30 pm

Re: Help with my math please

Post by NukeMMC »

Ok, this was bugging me and after sitting down and thinking about it, j-team is quite right. If you want to "zero" for 100yds at 25yds, the adjustments are 4:1. Since you have vernier sights, probably not calibrated in moa, it is best to set them for 2-2.5" poi above poa at 25yds and you should be close to center at 100yds.
If I knew your sight radius, I could tell you what your sight movement should be to achieve 1moa, or 1.047"/100yd
40xguy
Posts: 219
Joined: Thu Jan 21, 2016 1:25 pm
Location: Ohio. USA

Re: Help with my math please

Post by 40xguy »

forget the 25 yard stuff... Go to your club's 50 yard range, zero your rifle. now go up 6 MOA (whatever that is on your sights). shoot a few rounds at 100 to confirm... go have fun and hope you don't get frostbite in this cold weather !!! :-)
Hammer to shape, file to fit, paint to match...
Tim S
Posts: 2054
Joined: Mon Jan 03, 2011 11:33 am
Location: Taunton, Somerset

Re: Help with my math please

Post by Tim S »

About 2in (8 minutes) should do the trick, and be well into the black.
Shooterer
Posts: 331
Joined: Fri Aug 15, 2008 5:28 pm
Location: S.E. Wisconsin, USA

Re: Help with my math please

Post by Shooterer »

This has been very interesting to me, when I first thought of it I tried to remember from when I was a kid if a .22 dropped 8 or 10” @ 100 yard

The reply’s and the chart showed my memory is not that good. But looking at the chart that says there is about 7” different between 25 and 100, why wouldn’t holding that high at the shorter distance drop that much at 100?

What am I missing?

To answer the other questions, the rifle is a CPA 44 1/2 action with a Pope style stock and lever with a full octagon 28” barrel with a MO’s 22mm front globe and Baldwin midrange rear sight with a 29” sight radius
Attachments
4360F198-DF5C-49F2-8146-A9DC67075C85.jpeg
Bob Foth
Posts: 87
Joined: Wed Mar 03, 2004 1:00 am
Location: Colorado Springs, CO

Re: Help with my math please

Post by Bob Foth »

Beautiful rifle!!!
Martin H. added a key detail you didn't mention in your description.
Sight height is important as it determines the angular difference between the bore and the sight line.
From the photo, is it about 35mm center to center?
Post Reply