I'm zeroing in a scope this afternoon at 25 yards and was just wondering if someone might have a formula for me to use. This is for a 12 guage rifled barrel slug gun.

The distance between the centerline of the bore and the centerline of the scope is 1 13/16" Muzzle velocity of the slugs is supposed to be around 1475 fps. For lack of anything better I'm just going to guesstimate that drop at 100 yards will be 4", so I'll just sight it in about an inch low at 25 yards. Next week is first deer season here in Illinois and I'll zero it in at 100 yards then, but the closer to the bull I can get it now the better.

TIA for any help from someone who can actually suggest a real formula, rather than something I made up last night...

Get an estimate of the Ballistic Coefficient of your slug and then use one of the trajectory calculating programs to get an approximation to real trajectories under various conditions. Then you will have enough information for maximum point-blank range sighting...

Antonio

I think you are underestimating the drop of the slug...if I were you I wold sight it in at least 1" high at 25 yards and you should be on the paper at 100 (but low).

DB Bill,

You may be right, but remember that the scope is already almost 2 inches above the bore now. So if the slug travels uphill 3 inches in the first 25 yards it will have to start dropping soon after that. I seem to remember that most slugs only dropped about 6 inches at 100 yards but I'm going from memory there, which has been known to be optimistic in the past. I guess I'll find out in a few more days when I get home and can fire at a distance with it.

Oh, something that worked quite nicely when I was bore sighting it was putting a small LED flashlight in the bore and centering the croshairs on the circle formed on the far wall.

Rem 12 ga. 3" copper solids drop 9.3 inches in a 100 yards. Most slugs will drop a foot.

Using the Rem data, I get that you want to be +0.9 inches high at 25 yards, this will put you two inches high at 60 yards, dead on at 100 and 2 inches low at 120 yards.

At 150 yards you will be 8 inches low and dropping like a rock.

I have to use a slug gun here in Ohio. They will do the job.

Don

Don,

Thanks for the info. Unfortunately I went to the range already so it is zeroed in about 1/2" low at 25 yds, so it will be interesting to see where it goes at 100 yards.

This year I'm using Brennekes, but the only reason is that I got a huge bunch of them last year and haven't shot them all up yet. I don't like them much other than that. I used copper solids for a couple of years and other than the price I think they are my favorite slug. Before that I loaded up lee slugs for a couple of years, but I have problems working up a good accurate load for this gun of mine. Once I'm all moved back to the country I'll be able to give serious effort to developing a hard hitting and accurate load with them.

I'll post how low it shoots at 100 yards in about a week after I sight it in.