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

Going to the range this AM to sight in a Roberts with a new scope on it;I'll follow Mule Deer's advice and set up two targets;one at 50 and one at 100 yards.

Bore sighting at 50 will get me roughly POA at that distance,usually no more than 2-3 shots;and then I'll switch to 100 yards and see how she goes.....25 to 50 and 100 yards is warmup distance.....if time permits we'll run her to 300 after that

Mule Deer,

I suspect you'll keep traveling to some extent so you'll have something new to write about. I'd hate to see you recycle the same old pictures like some other writers. One of the things I like about your writing is that you don't rehash the same old stuff. Plus, you write it well.

Happy New Year,
Norm

I have had several loads which didn't go where they were supposed to downrange after 100 yard sight in. In most cases, the drop wasn't as much as I expected according to drop tables.
They weren't real far off...but I wonder; are the computer programs accurate? Is there a case to be made that the bc may not be correct?
Bill

That cat has been un-sacked a long,long time. miles

The fellow that taught me how to shoot was a Korean war vet. He used to tell me that the 25 yard zero was what the army taught him, but he said that he learned that about an inch or two low was better IF you had to do this in a pinch.



BC is dependent upon a variety of external factors; thus, it is not truly a constant. This is one reason that (when you could still buy them) Oehler's PBL used an acoustic-type device to aid in measuring the BC at the target. In the absence of the ability to measure BC, you can try determining bullet path at several different distances (the greater the number and the farther out, the better), then forcing your ballistic software to match the trajectory over the measured distances.

If you have enough data points and can shoot out to 400 or 500 yards, you don't really need ballistics software--a simple plotting program with the ability to fit data to two or three orders will suffice. They are free and on-line. I can highly recommend the Wolfram Alpha site. The interpolated results will be quite exact and the extrapolated results will yield more accurate results than if assuming a standard BC. You can then try this experiment again at different times of the year. Depending upon the weather and your location, you will see some variability, particularly at longer ranges.

I'm a clueless Canadian I guess - I only got hooked on NFL in the past few years.

S. Alberta is a nice jaunt for you and they grow em big over there. Ever hunted on this side of the Cdn Rockies - Cranbrook or the Elk Valley?

I had always heard of the 25 yd theory, but it was for a zero at 200 yds. Supposedly the fired round that bulls eyed at 25yds would be high at 100, then back down at 200.

Just a theory I read somewhere.

I keep hearing how the idea of a 25-yard zero is all wrong. I say BULLSHIT!!

No, it isn't the best method and every rifle should be checked at longer ranges to verify the sights, but the 25-yard method IS a very good start. For most rifles (with a scope mounted 1.5-2" above the bore) that shoot in the 2000-3000 fps range, a 25-yard zero will be pretty close to the best "point-blank" zero that everyone seems to like.

If a rifle is sighted in EXACTLY at 25 yards....you won't be too far off at any range up to 300-350 yards. The real key is that staement EXACTLY. Very small diffrences at 25 yards will result in very significant misses at 200 yards (for example...a 1/4" "miss" at 25 yards will be a 2"...or more..."miss" at 200 yards). That's why you should verify your sight-in at longer ranges.

However, a 25 yard zero is a VERY good method of getting the rifle close before exspending a lot of ammo at longer ranges sighting in and is an EXCELLENT way to check your sights in the field. Fire a single round in camp at 25 yards and know that if you are dead-on at that range....and you can be sure that you won't be too far off a at longer ranges.

The real key is that statement of EXACTLY. You can't be "close" at such short range.....you must be EXACT. The 25-yard method is not flawed.....it's the shooter that must be right.

Every rifle + load is different. My PH at Blaauwkrantz Safaris did the 25-yard check thing to me and I wounded and lost a bushbuck due in part to the un-needed scope changes (to 6" high at 100 yards). That and shooting off a corn sack full of sawdust instead of bags of sand. Took a Caldwell owl-ears front rest filled with plastic beads next trip.

What you do is take a 25-yard pre-shot target along with you to use at the scope check. Also you DO need to know where your rifle + load hits at 25-yards. I almost lost a warthog on my first safari at Mabelingwane because I didn't know to aim a bit high at close range.

I have 25-yard data to complement the rest of it out to 300 yards and...

Lts of myoads shoot 1/2" LOW at 25 yards despite being zero'd at 200yards in some cases, but mostly at 100 yards. Some are dead on at 25 yards and a few are 1/2" HIGH. The rule of thumb stinks!!

Every rifle + load is different. My PH at Blaauwkrantz Safaris did the 25-yard check thing to me and I wounded and lost a bushbuck due in part to the un-needed scope changes (to 6" high at 100 yards). That and shooting off a corn sack full of sawdust instead of bags of sand. Took a Caldwell owl-ears front rest filled with plastic beads next trip.

What you do is take a 25-yard pre-shot target along with you to use at the scope check. Also you DO need to know where your rifle + load hits at 25-yards. I almost lost a warthog on my first safari at Mabelingwane because I didn't know to aim a bit high at close range.

I have 25-yard data to complement the rest of it out to 300 yards and...

Lots of my loads shoot 1/2" LOW at 25 yards despite being zero'd at 200yards in some cases, but mostly at 100 yards. Some are dead on at 25 yards and a few are 1/2" HIGH. The rule of thumb stinks!!

My .243 neds to be about 1/5 low at 25 to be reasonably on point at 100. I fell for the 25 thing years ago, and learned about being 8 inch high, so much that I couldn't even find the holes in the 100 target. 25 may be the answer for iron sights. Anyone for 7 feet? Great groups except for the powder burns.

i haven't put much effort into the 25 yard zero check, but have done it enough to know that i can bore sight (from the bags at the 100 yard line) and generally get closer.

but i will not trust a rifle that has not been shot to the distance i zero it at. if i zero at 25 yards, it's GTG at 25 yards. period. ymmv

I'm sure that this is correct if certain ballistic parameters are met, but is not a hard and fast rule. I usually, when having just put a rig together, will sight in initially at 25 yards, striving for a POI about .5" to .25" low, and even then typically find it a tad high at 100 yards.

I will usually sight 1.5" to 1.75" high at 100 yards due to the huge majority of my shots being under 50 yards, but an occasional opportuinity may arise for no more than 300. And those are rare.

As far as BC's, I can get a better idea of what the true ballistic coefficient is by chronoing at two known ranges.

Zeroing and shooting at the ranges you will hunting at is what my experience has led me to believe is the best method. Sometimes those bullets are not so predictable.

I thought this 25 yard thing sounded familiar. Way towards the back of an old file I found an article from 1975. This was called "Simple Way To Sight In your Rifle" By Vin T Sparano. Outdoor Life Field Guide, November 1975.

Some friends of mine still swear by this. I would call it the lazy mans way to sight in a rifle. In a pinch, maybe but certainly not as a rule. If I can figure out how to scan this on my other computer and post it here I will.

For now, some snap shots of the "proof"!!

Heck, those look pretty good. I'll snap the other two pages and just post them here later.

The 25 yard zero is far from perfect on the other hand if you know the velocity, the height of your scope above the bore line and have a basic ballistic table it works in a pinch. I did shoot mine at 100 as soon as possible after I did this.

This is probably a stupid question;please keep in mind what I know about trajectory physics couldn't fill a .22 short casing, So I'm asking it anyway. If you're rifle is on at 25 yards and eight inches high at 100, If everything remains the same and you zero your rifle in at 100 yards will you be 8 inches low at 25 yards?

You will probably be 1" low at 25. The error of angle increases with distance. There are 2 places where the trajectory will cross the line of sight; both depending on the ballistic coefficient, velocity and sight height over bore. Remember, 1 minute at 100 yards is an inch, at 200 it is 2 inches. I feel that actually the other variables mean that 1 inch at 100 won't translate to 3 inches at 300; the group will be something of a increasing curved cone (someone find the name for this, please).

If the rifle has a removable bolt (as in bolt action), and a scope, I pass on the 25-50 yard sight in exercise entirely.

With a steady rest, I can usually bore sight any rifle to be on paper, and close to center, at 100 yards, with the first shot.

Saves on ammo.

However- just for grins, I entered my favorite .257 Wby. Mag. load, a 100 gr. Barnes TSX bullet at 3700 fps, altitude 5000'.

At a zero POI at 25 yards, the bullet crosses the line of sight again at 389 yards. Maximum rise above bore is 5.61" at 225 yards.
It is 3.51" at 100 yards. I guess if you are planning on doing some real long range shooting, the 25 yard zero ain't so far off!!