Home Forums Hunting & Shooting Ask The Gunwriters 25 yard sight in ?

If it is right on at 25 yards, it will be way low at 100 yards.



Bruce

Thanks! Nothing like a picture being worth a thousand words. That's about my experience too depending on scope height AND velocity. Pretty much sums up the graph of sight height vs. point of impact that I posted earlier.

BTW, I go to bed, get up and see this thread has gotten a bit off topic. . .

The example above of starting at 25 yards with a .22 Hornet served the purpose of getting on the paper. If his target is real, and the rifle is shooting that high at 100 yards, it is way out of bounds for the calculated trajectory, which indicates vertical barrel vibration. After he sights it in at 200 yards or whatever his intended hunting range happens to be, he will be able to record the actual height over and under the point of aim at 150, 100, 50 and 25 yards.

This little test proves our point about why you can't "sight in" at 25 yards, but you should be able to begin there. A rifle that does not shoot near the calculated trajectory needs tuning, or it will likely be limited to only one load, because it will throw other loads to another point.

Lee24,

I may be your only friend out here. I have no dog in this fight, but this target was shot from a controlled shooting environment including a heated shooting shed, 25 yard target board, and 100 yard target board.

The bench is built into the shed and the rest was sand bags. The gun is a Pre-war Model 70 in 22 Hornet. The bullet holes are fired ino this target at 100 yards after zeroing the rifle at 25 to get it on paper and eliminate as many variables as possible.



You can see by the target, the bullet holes continue to go toward the center from the 1st shot as I was adjusting the scope to be centered at 100 yards.

The 2 holes low and right of the bull were shot before making an adjustment up and left which shows the next 2 shots being low left of the bull. If you look at the upper left bullsey on the paper, you will see where my last shot printed, exactly where I want it.

All this shows is that the only paper you can count on to give you correct calculations is target paper.

Yesterday with that same 22 Hornet, I shot this rabbit in the head at 205 yards. Yes I had to hold over, but this gun is capable of extreme accuracy, making my point about where a gun prints on paper, just that much more valid...

" A rifle that does not shoot near the calculated trajectory needs tuning, or it will likely be limited to only one load, because it will throw other loads to another point."

Wow,...that's REALLY DEEP, Lee.

GTC

I agree that, "The only paper you can count on to give you correct calculations is target paper."

According to calculated trajectory, the shots at 100 yards should not have been that high. I explained my theory: barrel vibration, with the bullet leaving the barrel at the top of the vertical swing.

I have a .270 which does the same thing. It shoots a hot 140-gr load 2 inches higher at 100 yards than it shoots all the other 130-gr and 150-gr loads which I use.

That pretty much sums it up. . .

As most of us have too many rifles to remember what rifle does what at what distance, it would be wise to do your preferred sight in at 100 yards, then shoot at 25 yards, note the rifle's exact point of impact and record it for future reference. This way, you can perform a 25 yard zero if necessary.

My local outdoor range is fifty yards. I've found that most of my rifles, when sighted in two inches high at 100 yards, are an inch high at 50 yards. This works for me as most shooting in the eastern woods is within 100 yards.

Shrapnel,
Out of curiousity, what is the velocity of this load? I use both Sierra and Hornady VMax's depending upon what I'm hunting.

This makes sense to me. The closer you are to your muzzle, the larger the error at increased distances.

1.5 inch high mounted scope with a high power spitzer big game hunting load will be 3\4 inch low at 25, dead nuts at 50 and an inch and a half high at 100. Math was exactly the same with shrapnels hornet. Amazing.

An AR with it's iron sighted dead nuts at 50 is 2 inches high at 100. Wow.

Life just does not have to be tough.

Still haven't seen the math on Shrapnel's Hornet, so I guess I can't comment on his situation. I do know what my hornet does, and it varies greatly to what I reload. Maybe I'm missing the tone of your comments, but for your "high power" 3/4" low is a far cry from 25 vs. dead nutz at 25 for 100 yards. It makes that kind of difference. The higher the sight, the worse it gets. Looks to me like you are nearly what the RCBS program predicts.

Dead on at 25 will almost always run you 1 1\2 high at 50, and around 4 1\2 to 6 high at 100. Try it at the range next time you go it is very repeatable with almost every high power rifle. I'm not even being a smart arse.

Yep, that's been pretty much my experience. Forgive my skepticism. When certain folks begin to post, its kind'a hard to tell the difference.

Hey Schrapnel, at least that Hornet didn't blow up. Oh thats right you only do that to Colts.

Don't get hung up on 25 yards.
If your scope is high, or the rifle shooting high at 100 yards, set the target at 30 yards for a starter. Every yard makes a big difference between 25 and 30.

.22 Hornet with 45-gr HP at 2700 fps
Range Drop
(yd) (in)
25 0.0
100 2.7
200 0.8

.308 Win with 150-gr spitzer at 2800 fps:
25 0.0
100 2.7
200 1.7
230 0.8

But they work out better with iron sights.
This 25-yard rule originated in the days when most rifles had iron sights, and not so many fast loads.

Bruce,

Yourself and MuleDeer are of course correct...The penny finally dropped that I was moving the whole trajectory up or down by 5" when in fact it doesn't work like that..

All I can say was it was about 3am when I made my original post and I was obviously half asleep!

Regards,

Peter