100 yrd Zero on a Metric 100m Range

[springbok787]

Hi Guys and Girls (not wanting to leave anyone out),

Apologies that my second ever post is a technical question, but I want to get right.

I have a new rifle that has been bore sighted and just as a check laser sighted at well.

At sometime in the next couple of days I am going to pop to the range and complete the zero process, which is something I am comfortable with by the way.

My problem is I want my rifle to be 1" high at 100 yrd's, but the range I am going to zero on is a 100m metric range. This means if I zero 1" high I will be 1" high at 109.36 yrds not 100 yrds. Which might not seem like a massive amount of difference, but I want my rifle correct because in my mind even a slight difference might compound a field based human error. Also 1" high at 100 yrds is where the estate rifles I have been using for a while now are and I am comfortable with the bullet trajectory etc at this. I think confidence is a big part of this, but confidence in our shot placement is important in my mind.

I have used a ballistic calculator set to metric and then converted to imperial to get the answer I think is correct, but I wanted a second opinion if anyone has the time please.

The technical:-

Tikka T3x in .243
Sako Gamehead 100gr

Just to answer a few of the likely answers I do have access to the ranges at Bisley as an NRA member so a 100yrd range is possible, but at present my wife is pregnant with twins and within a month of popping. Therefore traveling the 2hrs to Bisley isn't a massively good idea for my health and general wellbeing.

I have also check the ballistic tables for a the ammo to get an answer, but like I said I wouldn't mind a second set of eyes checking this as well.

 

[Hornet 6]

Two simple answers.
If safe move forward 9 yards.
Take an artists easel (or similar) to hold target and place it 9 yards closer than the range target.

Neil.

 

[Jon Smith]

even simpler, don't worry about it

 

[Firefly]

By my reckoning you need to zero at 100m to be 1.03" high. Ff

 

[Axxxel]

What are you going to use the zero for? Do you use target turrets and shoot long range, or do you just want to be able to hold straight on your target out to say 200 yards, without the bullet deviating too far from the line of sight?

If the latter, then just shoot 1" high (I'd prefer 1,5" with a .243) at 100 meters and don't worry about it.

The difference in impact point between 100 yards and 109 yards is very small, especially with a .243.

Edit: I missed Firefly's post. That's right, you'll need to shoot well enough to reliably measure 0,03" to even notice the difference. Study some ballistic tables and compare the numbers to real life situations.

 

[springbok787]

Thank you for confirming that the difference is a ridiculously small amount and not worth worrying about.

It was the super small difference that had me doubting my work out.

Impressed by the speedy responses as well.

 

[Yorric]

Unless you shoot a large number of bullets into a group the mean point of impact cannot be determined accurately. The impact difference between 100 yds & 100mts is small enough to be almost unmeasurable / irrelevant within the group pattern / spread.
Predicting bullet drop at longer ranges is always best done by test firing at those ranges as real world bullet drops can often highlight errors in using ballistic calculations.(Velocity, bullet ballistic coefficients, atmospheric conditions etc etc.)
Sooooo - zero at 100 yards or metres, then go out to longer ranges ( say 200, 250 & 300) & measure the drop you actually get (shooting enough bullets to get accurate group mean point of impact at each range)
Don't over think it - Shoot plenty & see what happens!
Then go home & load some more ammo! LOL.

Have fun

Ian

 

[Alantoo]

Agreed not worth worrying about.

You will be doing well to have around an inch group at 100 yards so some shots will be 1/2" high and some 1 1/2" high. Assessing the best nominal 1" high POI I found best done with a raft of shots over a period. The deer won't notice the difference.

Alan

 

[bluesako]

imho its not worth the bother 100yds or 100 mt,s just go and shoot your new rifle and enjoy bs

 

[JTO]

If you've got half minute clicks on your scope, you won't be able to get fine enough adjustment to be more accurate anyway.

 

[Woodsmoke]

8 1/2 yards won't make any significant difference in real life shooting. If it's important to you to get it spot-on though, just bring a target closer if you can? I know myself that half a grain of powder makes absolutely no odds to my hunting load, but it doesn't stop me obsessing over getting it absolutely precise

 

[User00001]

You had better hope that it is a 0.1 MOA grouping rifle in order to tell if you are 1'' or 1.3'' high!

Surprised to hear someone who is clearly interested in precision buying into the 'one inch high and hope for the best' method of zeroing/shooting?

 

[25 Sharps]

Agreed not worth worrying about.

You will be doing well to have around an inch group at 100 yards so some shots will be 1/2" high and some 1 1/2" high. Assessing the best nominal 1" high POI I found best done with a raft of shots over a period. The deer won't notice the difference.

Alan

Why? Every CF rifle I own shoots under an inch at 100 off of a bench

 

[Woodsmoke]

shoots under an inch at 100 off of a bench

Bench shooting and stalking are two different things though, aren't they? You just can't guarantee a steady enough rest while stalking to give you the absolute best accuracy your rifle may be capable of.

As an aside, I used to know a bloke who claimed he could almost keyhole his .308. Turned out he was locking it so hard into a cradle he ended up cracking the stock. He then sold it on to another bloke who had the sling swivel fall out during a stalk and finished the job. I've been deeply-cynical about the majority of sub-MOA groups ever since

 

[Selous]

The difference between yards and metres are not worth worrying about below 300 yards/metres.

Take a chill pill and don’t worry about it

 

[Jagare]

My back garden rifle range is 112 mtrs and i sight all my rifle dead on at that range. I've never given it a thought that a few mtrs more or less would make any difference. Many more important things in life to worry about.

 

[25 Sharps]

Bench shooting and stalking are two different things though, aren't they? You just can't guarantee a steady enough rest while stalking to give you the absolute best accuracy your rifle may be capable of.

As an aside, I used to know a bloke who claimed he could almost keyhole his .308. Turned out he was locking it so hard into a cradle he ended up cracking the stock. He then sold it on to another bloke who had the sling swivel fall out during a stalk and finished the job. I've been deeply-cynical about the majority of sub-MOA groups ever since

But the OP is talking about zeroing at a range and therefore he'll presumably be shooting off of a bench, which means with ammo matched to a decent modern CF then 1" should be the norm if not better rather than doing well if he shoots an inch.

In terms of a rest I find quads very close to being prone with a pod, longets bunny off quads is 237 yards and headshots at 150+ with the bunnies are doable. Not blowing my trumpet but I don't get how people think field accuracy should fall off a cliff compared to range accuracy, get out behind the trigger enough and it becomes second nature.

PS keyhole is the sign of a tumbling bullet and not desirable.

 

[Alantoo]

Why? Every CF rifle I own shoots under an inch at 100 off of a bench

Good for you.

I was at the Monmouth Tunnel range last night and for the BDS day last Sunday. There were very few sub 1" groups there, even from varmint / target barrelled rifles.

The OP has what sounds like his first rifle, having used estate ones previously, so he is only just zeroing it for the first time and has yet to find what ammunition it likes. All factors to indicate he will be doing well to shoot within an inch.

As for your shooting under an inch with every rifle...how much under an inch? Does the same premise not apply even if you always manage 1/2" 5 shot groups? I.E with a nominal 1" high at 100 you will be having bullets passing between 1.25" and 0.75".

Alan

 

[Markfox]

I randomly check my zero but I just put a 3 inch round plate out to 200 and shoot it resting on a bag on the bonnet , if it hits job done I’m not really fussed where it hits on it as thats the furthest i shoot and itll still be a dead deer

But just for reference it’ll be about 2” high at 100

 

[Woodsmoke]

keyhole is the sign of a tumbling bullet

Apologies. I should've said 'buttonhole'!!! I agree with you to a degree about the accuracy, but the truth is a large proportion of shooters aren't practicing enough to be able to get the best out their outfit. Hence my somewhat generalised statement about accuracy in the field