unheard of zeroing procedure..what you think?

[sauer]

ok guys want to run something past the more informed person on here.

 

im working with a canadian here true gent good laff.etc etc.

 

anyway he hunts and has family who hunt but have miltary experience also....

 

he tells me they now zero, instead of inch high @ 100yrds or so, they

 

zero @25 YARDS !!!! and it does out to 250 -300yrds!!!!!! theory being that the bullet actuall rises as leaves barrel and point is same as 250yds ish!!!

 

ive never heard of this and was dubious but he put me to following link

 

 

 

www.huntingclub.ms/index.php?page=175

 

 

so anyone esle here of this...?

 

im still dubious but he swears his brother told them how to do it and way saves on ammo and time for zeroing.

 

 

 

sauer

[menial 1]

Keeper local to me does the same and shoots an awful lot of fox each year. His job depends on it so there must be something in it.

[sauer]

hi menial

 

yeah guy must have seen look on my face when he was telling me,, he had same reaction when out zeroing and his brother on leave ( from military where he was taught same ) appeared and told him how to do it.

 

he says he didnt beleive it either so stepped aside then watched as checked it at 200 yrds bang on !!!

 

now he doesnt do it any other way. he swears by it. Says he doesnt use half the time or ammo doing it now either.

 

 

 

mmmmmm

 

canna wait to get off o this rig now and try it out for noseyness

 

sauer / paul

[Chris-NZ]

The bore-to scope height is a major significance in this.

It'll more than get you on paper at 200yds but I'd never rely on it for anything smaller than large deer.

 

Chris-NZ

[eldon]

I will try my 200 yd zero next time I am out as I'm curious but I can't see why it won't be near.

 

Certainly makes it easier for a check shot as 25 yds is easier to find and a lot quicker.

[casts_by_fly]

like chris said, it will get you pretty close, but not exact. The problem is that if you are 1/4" off at 25 yards, you're 2" at 200. When you look at 1/4" at 25 yards, that is probably smaller than a bullet hole for most people so you'd ignore it. 2" off is too much for me. If you and your gun can shoot MOA at 200 yards, then you could be 4" off using that method. Not the end of the world for Elk, but probably a miss on a fox.

 

That said, this is a great way to get on paper quickly. If I want a 100 yard zero, I'll start around 30-35 yards and get it close. Then you'll be on a sheet of A4 at 100 yards in just a couple shots.

 

Thanks,

Rick

[jon]

It gets 'close enough', I used it to check after someone knocked it in the car. But I had already checked it at 25 when I sighted in originally.

I suppose those 'red dot' gadgets are on the same principle?

If I run my ballistic prog at 10 yard increments for 200 yard 0 - I'm 0.1" low out at 30. ... saves a walk and cartridges. and .

[Guest Scotland Rifles]

In that case.

 

do you zero spot on at 25 yards IE:no 1" high,

 

sounds good to me. i read it in a stalking book of some age a long time ago, but put it down to old times zeroing (if you know what i mean)

 

bob.

 

Just found this,

 

 

 

Rifle Sight-In Philosophy

 

I just ain't that good of a shooter, ammo is expensive, and every time I blink wrong its magnified by four at 100 yards.

 

I always sight-in a rifle at TWENTY FIVE YARDS, KNOW my BALLISTICS, & PRACTICE

 

Sighting at 25 yards minimizes shooter error so its easy to diagnose problems or discern between equipment, environment, or shooter technique (bad habits?).

 

Bore sighting should get the first shot on the paper. At 25 yards, you probably won't need to bore sight.

 

Use the Maximum Point Blank Range (MPBR), which is the distance at which the bullet rises and falls about 3 inches below the line of sight.

 

Since I refuse to sight-in a rifle past 25 yards, I usually stick with 1/4" high at 25 yards in the same hole. Then I check my impact at 50 to see if my ballistic calculations are correct by doing a little reverse engineering since I don't have a chronograph. Then I do some tweaking of the figures. If you don't do anything else, 1/4" high at 25 yards will make you "hold on" deer capable out to at least 250 yards with most popular calibers with velocities above 2500fps.

 

Most advertised velocities are measured from a 24" barrel. The accepted rule of thumb for velocity loss per inch is as follows:

 

For rifles with muzzle velocities in the 1000-2000 fps range, the change in velocity for each 1" change in barrel length is 5 fps.

For rifles with muzzle velocities in the 2001-2500 fps range, the change in velocity for each 1" change in barrel length is 10 fps.

For rifles with muzzle velocities in the 2501-3000 fps range, the change in velocity for each 1" change in barrel length is 20 fps.

For rifles with muzzle velocities in the 3001-3500 fps range, the change in velocity for each 1" change in barrel length is 30 fps.

For rifles with muzzle velocities in the 3501-4000 fps range, the change in velocity for each 1" change in barrel length is 40 fps.

 

Sighting at 25 yards works.

[nemasis243]

Excuse my ignorance ,but how can a bullet rise??

If zeroed at 25yrds how will the bullet climb

I was watching a long distance shooting video by defencive Edge and they say its beyond the laws of gravity for a round to go higher than the bore line when fired?

[jon]

In that philosophy from Scotland Rifled above the most important bit is

" KNOW my BALLISTICS, & PRACTICE .."

Nemasis .. you're right: a bullet drops from the the line of the bore but over the distance it coincides with the line of sight twice. In this discussion the particular load does it at 25 and 200 ....

[Laurie]

It's because the sight is set above the bore centreline - quite a bit above the bore in the case of some scope sighted rifles. So, if the barrel is level, the line through the centre of the scope (the sight-line) points down slightly. Put it the other way round, if the sight-line is level, the barrel points slightly up and the bullet intially rises after it leaves the barrel.

 

The sight-line and bullet trajectory will coincide a short distance from the muzzle, but as Chris points out, the exact distance varies according to how high the scope is mounted (and also what downslope it has through a canted mounting rail say for long-range shooting). That's why all good PC ballistics programs ask you to input 'sight-height'. If you don't they usually assume it's 1.5", but if your actual mounting is significantly different that can have an effect on the accuracy of the results.

 

The military have long used a special zero-target on their 30M full-bore ranges, or on ad-hoc 'zero ranges' they'll set up at bases in the field to check their rifles' zeroes before action or after armourer work on the piece. Remember though, they can do this as they have one particular weapon with a fixed sight-height above the bore and only use one cartridge with one set of external ballistics properties. Put the bullet into the appropriate part of the target at 30 metres and you know it's sighted in for 200M, but only with the SA80 and 5.56mm L2A2 62gn ball round.

 

The easy way to do it on your rifle is to sight-in at whatever range you want, say 200yd, then shoot at a target at 25 or 30yd, and note where the bullets hit in relation to the aiming mark. Sighting in with that load at that exact range to hit the paper at the same spot on or above the aiming mark should see you back on again at whatever range you sighted-in at originally. Of course, if you change the scope mounts so the scope is at a different height, you're back to square one.

 

Incidentally, because the barrel is below the sight-line, it means the bullet initially flies through the space below what you see through the scope. This can be important if you're shooting over an obstruction just ahead such as a wall or fence - or your expensive chronograph! It's easy to think you're above the chronograph body if you see it below the crosshairs in the scope and end up clipping the top - been there, done that!

 

 

 

Laurie

[brown dog]

I think we must think seriously about tolerances here.

 

"Bang on every time" to one man is quite likely to be "like mad woman's sh't" to someone with higher expectations.

 

 

 

How big's a 25m group? My best 100m 308 groups look like so-so 25m groups.

 

On a 0.1mRad click scope (ie 1cm at 100m), each click is only moving things 2.5mm at 25m.

 

Soo… will 25m groups be small enough to assess MPI being off by 2.5mm? I suspect not.

 

Compounding this: When does a particular round settle? For many ammo types, 25m is too close.

 

Fine for someone who's happy with minute of moose at 200yds (being off a bit will get lost in the noise), but no good for most here.

[brown dog]

Excuse my ignorance ,but how can a bullet rise??

If zeroed at 25yrds how will the bullet climb

I was watching a long distance shooting video by defencive Edge and they say its beyond the laws of gravity for a round to go higher than the bore line when fired?

 

Yes, gravity means that a bullet can only ever drop in relation to the boreline -people confuse themselves when talking about the bullet rising in relation the the LOS (which, initially, it does).

 

 

[just to contradict that at the real nerd level, a bullet can be flung higher than the boreline by the phenomenon of jump (sometimes called 'barrel whip') -not worthy of further consideration in this context though]

[Laurie]

I think you have to think seriously about tolerances here. (Brown dog)

 

Good point.

 

Apart from snipers, the military work in Minute of Figure 11 or equivalent at 200 yards and in my experience some of them have trouble hitting same at this range - and that's without the Fig 11 shooting back like yer actual Taliban fighter!

 

The other thing a lot of people forget is that the military are now as constrained by health & safety rules as people in any other company or workplace. In this atmosphere, it would be regarded as quite inappropriate to take a rifle onto a full distance firing range unless it's been sighted-in previously at short range on a SUITABLE facility. If you look at what this entails, that means an overhanging concrete canopy above the backstop and high side walls so it's impossible for wayward shots to escape.

 

For our shooting, this sort of sighting-in is a way of getting on the paper, not for getting pin-point accuracy. It's a good way of doing an initial sight-in if you have a 25 or 30yd/M facility which soldiers do, and maybe some people with a small field behind their houses, and no neighbours for three miles around like a few gamekeepers in remote areas, but otherwise of little value to most people in this country.

 

Laurie

[nemasis243]

In that philosophy from Scotland Rifled above the most important bit is

" KNOW my BALLISTICS, & PRACTICE .."

Nemasis .. you're right: a bullet drops from the the line of the bore but over the distance it coincides with the line of sight twice. In this discussion the particular load does it at 25 and 200 ....

 

 

Thanks for clearing that up for me ,

cheers Andy

[eldon]

But at least with a pre shot zero and then logging a check shot at 25 yds you would know if anything had moved i.e. a full turn out on your scope

 

I suspect most on here have done this at some time.... maybe I have as well

[MarinePMI]

In the US, this is referred to as "BZO" = Battle sight ZerO

 

It's close enough for a man sized target at 200-300 yds, but definitely not an accurate way to truely zero a rifle for a known distance further out. (8/3 -2 for the USMC modified M-16A2's)

[Andrew]

It is a fine way to sight in but, as my Marine buddy pointed out, NOT for zeroing at a specific range. It's used for the basis of establishing a point blank range for that cartridge. I use it all the time, especially when mounting new glass and especially on big game rifles. I sight at 25 yards, correct windage at 100 yards and depending on the cartridge, leave it a couple inches high at that distance. For a heavy thirty (30-06) I leave it 3 inches high. This allows me to hold (elevation-wise) in the middle of a deer from hair burning close to 300 yards distant and hit the kill zone. ~Andrew

[menial 1]

But at least with a pre shot zero and then logging a check shot at 25 yds you would know if anything had moved i.e. a full turn out on your scope

 

I suspect most on here have done this at some time.... maybe I have as well

 

[Millwall Paul]

I had this when I went to Africa, the guys out there wanted us to check zero just at 25 yards, due to my ammo going missing between Joberg and PE, i was using camp ammo. The shots looked good at 25 yards, but when I had my first shot of the safari it was a miss. Checked zero again on the range properly at 100 and it was 2'' to the right and low. Swapped back to my ammo as it had arrived and zeroed it properly at 100 then checked at 200 and was happy for the rest of the trip. I'd never rely on a 25yd zero - ever. Like people have said good for a quick check in case anythings miles out but thats it.

[Andrew]

I had this when I went to Africa, the guys out there wanted us to check zero just at 25 yards, due to my ammo going missing between Joberg and PE, i was using camp ammo. The shots looked good at 25 yards, but when I had my first shot of the safari it was a miss. Checked zero again on the range properly at 100 and it was 2'' to the right and low. Swapped back to my ammo as it had arrived and zeroed it properly at 100 then checked at 200 and was happy for the rest of the trip. I'd never rely on a 25yd zero - ever. Like people have said good for a quick check in case anythings miles out but thats it.

 

What was the caliber you were shooting?~Andrew

[Millwall Paul]

I was shooting my 30-06 with 168gn TSX's when they turned up and the camp privi partizan 150gn ammo. Once I re-zeroed at 100 at about 1.5'' high it was good for aiming bang on out to about 225 yds.

[Andrew]

That's odd as I sight in my 30-06 (well, rough in) using the 25 yard method without a hitch! I guess you never can tell.~Andrew

 

PS: Dare I ask what you missed??

[Millwall Paul]

That's odd as I sight in my 30-06 (well, rough in) using the 25 yard method without a hitch! I guess you never can tell.~Andrew

 

PS: Dare I ask what you missed??

 

I missed an impala at approximately 225 yards, should have been an easy shot but I blew it. I hate blaming my gun / ammunition but I should have made that shot. I know now as well that my rifle (sako 75) doesn't like privi partizan. Myself and another hunter had to check the zero on a camp rifle for one of the other hunters and they were using the privi patizan ammunition and it shot like a shot gun grouping wise at 100, at 25 it looked good, but not at 100. Changed ammo to federal fusion and it was pulling 1/2" groups at 100, maybe it was just a dodgy batch of ammo, but I'll never trust the 25 method again without checking it at 100 after.

[Andrew]

Impala. Ouch!

The 25 yard method is just for roughing in. Period. It works well for that. As I mentioned, I use it for mounting scopes. I used this method with my daughters 243 this past fall. I mounted a new scope and put it to hit POA at 25M. At 100 it just needed a bit of left windage. Total rounds expended: five. I would never use it without checking at 100... unless that was the maximum range I was going to shoot at in which case, it would work on deer sized game.~Andrew