Minimum Distance to Bore Sight

What's the gun?

Doesn't matter what's the gun.

Bore sighting must be done at a target, or any visible small object at least 100 yards or further, to make up for the distance between the bore line and the scope reticule / sight line above the bore.

Bore sighting at closer range will result in shooting over everything you shoot at beyond 50 yards or more.

I use a telephone pole insulator a block+ behind the back yard fence when I mount scopes at home.

rc

The reason I asked was that not all guns can be visually bore sighted. My Garand can't nor my SKS . My AR'S can't unless you remove the bolts.
Now if you're using a laser, you can.

Well, you are completely right about that.

I guess I was thinking he had a bolt-action, or other rifle like an AR-15 he could easily see through the bore to bore-sight it.

Or he wouldn't have ask how far away to bore sight it.

My mistake!

rc

I bore sight mine at home at 25 yards. That gets me on paper at the range. Once I zero it at 25 yards, my ballistic calculator tells me how many clicks to adjust for whatever other distance I want. With my .257 WBY, it was -11 clicks for 100 yards. That took me to about an inch from 100 yard zero (my scope doesn't do the -11.3 clicks called for).

I've got to go with fellow Tennessean HexHead on this one. Assuming that your scope's line of sight is 1 1/2" above the bore, dead on at 25 yards will put you 2.7" high at 100, 1 1/2" high at 200, & dead on at 225 - with a 165 ish grain bullet. That is about where you want to be if you want to forget about bullet drop & just hold dead on out to 275 or so - - you will never be more than + or - 3" until you get beyond 275.
Since bore sighting is not all that precise anyway & you will have to shoot the gun at 100 yards or more to get it really zeroed, you just want to get it close, & bore sighting on small dot at 25 yards ( I use one of those target stickies on my mailbox) will do the trick.

I'll go along with HexHead and Vol46.

I've bore sighted a couple of rifles at 25 yards just to get the shots on paper before moving the target out to 100 yards.

I use a bore sight tool at home. It works very well. I use the old school method of bore sighting at the range.
But a good bore sight tool should have you one paper pretty good at a 100 yards.

Same here. I look through the barrel at 25 yards when the gun is on a rest. Then move the crosshairs to POA center bore and center scope.

It does put me high at 100 yards, but then I just work it out by shooting 3 shot groups, but I am on paper and pretty darn close with this method. Saves some ammo at least.

But I can see where bore sighting at 100 yards would be good, also.

I bore sight by looking through the barrel @ 50 yards. I only want to get the 1st shot on paper @ 50. Chances are VERY good that you won't have to readjust anything. Do a quick bore sight at home, unless it is obviously WAY off don't sweat it. Go shoot it to verify.

even after you bore sight the rifle you still have to shoot it to see where the bullets will actually hit on the target

so did you actually remove the scope when you cleaned it up? even if you did I would just remount the scope just close as you can and set a target at 25 yards and fire a couple of shots and see where they hit. I would set it for dead on windage wise at 25 yards and maybe an inch or two low at the same distance. then move the target to 100 yards , see where it hits and make the required adjustments. I have an old Bushnell collimator and well I used it , I always thought it was a waste of as at least half of the time the first shot would barely be on paper at 25 yards

I know. I'm just trying to cut down the amount of time it takes to make sure everything is still in order.

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I bore sight at 15 yards or so (from one end of the hallway to the other) with a laser, 25-30 yards (from the kitchen to the building in the back yard) if looking through the bore.

Works for me. I always verify windage at 25-30 yards at the range, and work out elevation at further distances, and adjust to whatever final zero I want. Not a ton of science is involved. Put the dot on the crosshairs or put the crosshairs on whatever you're looking at through the bore, and then hit the range.

The military has boresighting targets that have the offsets built in for different sighting mechanisms. The intended distance on the ones I am familiar with is 10 to 25m. They work surprisingly well.

My Garand can't nor my SKS

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??? I boresighted my SKS. A rifle does not have to lock up on the bore sight. as long as you can insert it in the bore and look through the sights, who cares what the bolt is doing or even if it is in the rifle?

To he OP: I bore sight in my home at the longest distance I can create. It will be accurate enough to get you on paper at 25m. Work it at the range from there. Hint: rotate the sight in the chamber. sometimes they will be a little off, and rotating around will show how much it wanders... give you an indication of the "error" inherent in the bore sight.

I boresighted on a lightswitch in my kitchen the other day when I installed a new scope on a new rifle, just to get it on paper on my first shots at the range. It worked and a few shots at the range and I was in business. It was dark outside and I was impatient, so I couldn't use an outside target at a farther range. I also didn't use a boresighting tool, I simply rested my rifle, removed the bolt, looked down the bore and centered it on an identifiable object and then centered the scope crosshairs on the same object. Sure, it was high when I first shot it but I was on paper and corrections are easy.

Lasers and collimaters are wonderful tools but the method in question is removing the bolt, locking the firearm in place, center a pinpoint target thru the bore, and adjust the scope reticle to match the bore picture. When you do not have a laser or collimater(spud/grid,etc.) at hand this procedure will get you on paper. While 100 yards would be ideal I'm sure 25 yards or even 50ft. would suffice in a pinch. I personally would fire the first shot at 25 yards adjust if needed and then go to 100 to get it zeroed in but I've started with 100 yds. with a good, solid backstop and had good results.
I've seen guys bore sight their rifle and go hunting. IMO to cleanly, humanely take an animal you MUST KNOW your firearm is dialed in properly.

I'd boresight at 25 yards if that distance is available. It's the point that
scope height/line-of-sight and the bore itself should largely overlap for
point blank shooting out to 150-200 yards for medium bores (30 caliber/2,700fps).

That said, you're on paper which that technique, but only so-so at most.

Just a quick addition... I've found a great way to boresight that has worked for me. I do it preferably at night. I set a little penlight as far away from the rifle as practical, pointed at the rifle. Look down the bore and center it on the bright light, then adjust the scope to the light. It has always gotten me on the paper at 50 yards... sometimes very close.

In my case, I put the rifle in my rifle vise to hold it as steady as possible.

Man bore sighting at 100 yards, at my age I can't even see 100 yards without the use of a scope. Thank God for laser sighting aids.

I've had pretty good luck with using the cartridge-style laser boresighters to verify zero at fairly close range (like 25 yds), but there is a trick involved.

The instructions said to sight-in using a conventional procedure at 100 yds or so, then insert the boresighter and mark on a small card the position of the scope's reticle and the red dot from the boresighter. (Labeling each, of course.)

Then, according to the maufacturer, if you suspect the scope mount or reticle has moved as a result of a drop or fall, you set the card up at the same distance, insert the laser boresighter, line up the reticle with the reticle mark on the card and see if the laser dot still falls on its previous location.

If they are coincident, you are good. If not, you need to sight in again. Or, at a minimum, check rings for tightness and adjust reticle until laser and reticle are coincident with their marks. (However, this is based on several assumptions which only shooting the rifle can verify.)

The interesting thing is, nowhere in the instructions did they suggest using the laser at longer range...

The method I use is usually boresight at 50 yards to get on paper. Fire a shot (at 50 yards), adjust the scope after that shot to get it closer to center. Move out to 100 yards and fire a shot, adjust the scope again, then fire a confirmation shot to make sure I'm in the ballpark.

3 shots and about 10 minutes, at most, and I'm usually within 1/2" to 1" of where I need to be. Take it out a little further to do some fine adjustments if I feel the need.

Used this method a few times and I've been close enough (with my shooting skill) at 300-400 yards to feel comfortable that anything I shoot at will be hit where I want it to be hit.