Zeroing for ETs

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Tim L
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Zeroing for ETs

#1 Postby Tim L » Mon Jan 18, 2021 5:18 pm

As we all know, hitting the edges of an ET can be rather expensive. Zeroing by shooting into the butts can also be a bit hit and miss as it's reliant on spotting the fall of shot which isn't always possible due to wet sand or grass on the butt stop.
One solution I'm looking at is putting a target at 30m and zeroing on that. I have found, using applied ballistics, that if you then just add 3moa for 300m and 3moa for every further 100m the fall of shot will be within 2 minutes for all my f class loads right back to 800m. Thats 155s at 3200, 200s at 2750, 7mm 180s at 3000, 6mm 103s at 3000.

At 30m the holes will be easily visable and will confirm windage well enough for the objective.

Does anyone have a load that if zeroed at 30m does not fit this rule?

Hunting rifles won't achieve these velocities so just f class and tr loads for now.

tachyon
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Joined: Mon Jul 15, 2019 1:44 pm

Re: Zeroing for ETs

#2 Postby tachyon » Mon Jan 18, 2021 8:52 pm

Hi Tim,

The range you zero a rifle at does not do anything to change the bullet trajectory. What you have done by zeroing at 30m would normally be considered a zero at about 250 yards. Zeroing like this, at something around the maximum point-blank range, is very common in hunting rifles but makes less sense in a target gun.

Rather than mess around with inherently inaccurate rules of thumb why not make a simple table that tells you exactly the elevation you need at each distance? JBM Ballistics will do that online for you, for free, in about 20 seconds. https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi



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pjifl
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Re: Zeroing for ETs

#3 Postby pjifl » Mon Jan 18, 2021 9:02 pm

If you zero at a close distance, the height of the scope becomes quite important. Not saying that the suggested method is misleading.

Berger also has a good online calculator for trajectories.

Peter Smith.

Tim L
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Joined: Mon May 19, 2014 7:11 pm
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Re: Zeroing for ETs

#4 Postby Tim L » Mon Jan 18, 2021 9:19 pm

tachyon wrote:Hi Tim,

The range you zero a rifle at does not do anything to change the bullet trajectory. What you have done by zeroing at 30m would normally be considered a zero at about 250 yards. Zeroing like this, at something around the maximum point-blank range, is very common in hunting rifles but makes less sense in a target gun.

Rather than mess around with inherently inaccurate rules of thumb why not make a simple table that tells you exactly the elevation you need at each distance? JBM Ballistics will do that online for you, for free, in about 20 seconds. https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi



Screen Shot 2021-01-18 at 9.49.54 pm.png


Its not about my guns Tach, I have all my elevations. (Im a tight git, I don't like wasting sighters)
The aim is not to have an accurate zero. The aim is to be able to zero a gun, any gun, well enough to stay inside the edges of an ET.
For example when a shooter has a new gun. Or has fitted a new barrel. They turn up at the range on a 700m shoot. We have no idea of velocity but we can get them to zero at 30m then wind up 15mins and be on the target.
It works for all my loads. 1 rule fits all is far better to pass on t o other ROs th a n a table or chart they may not understand.
The question posed is does that rule fit your loads?

Tim L
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Re: Zeroing for ETs

#5 Postby Tim L » Mon Jan 18, 2021 9:21 pm

pjifl wrote:If you zero at a close distance, the height of the scope becomes quite important. Not saying that the suggested method is misleading.

Berger also has a good online calculator for trajectories.

Peter Smith.

Totally agree, but I can't run every possible combination through a balistic ap myself. Hence asking if people could check their own and let me know.

AlanF
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Location: Maffra, Vic

Re: Zeroing for ETs

#6 Postby AlanF » Tue Jan 19, 2021 6:34 am

Tim,

At Rosedale we've tried a few different methods in an effort to protect our Hexta electronics. We hadn't considered a short range zero from the mound because of the need for a bullet catcher. We've ended up concluding that a manual target at the beginning of the first range is the most time efficient, provided you have an experienced marker and everyone gets to the range on time. A good marker can hear where a miss goes, and on most ranges see the strike on the stop butt, and suggest MOA adjustments. As soon as a shooter has a confirmed shot on the manual target, the next one can start. And usually a start can be made on the Hextas while the marker continues. Occasionally the zeroing process won't be necessary e.g. "zeroed at 100yds earlier", or "300yds so can reliably boresight" etc. We leave it up to the RO to decide exemptions.

Cliff Austen
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Location: Sydney NSW Australia

Re: Zeroing for ETs

#7 Postby Cliff Austen » Tue Jan 19, 2021 10:36 am

At Nowra we put up a "splash target" for every distance. Everyone has to fire at it. If your shot hits the BLACK the marker will radio back "QUALIFIED". I you hit the white or miss the target you are coached until you put a shot in the BLACK.
This process, if managed correctly, will get people shooting on the ET's very quickly.
We had 38 shooters last weekend. Two targets up, 3 shooters per target at the same time, using OZScore Targets.
Cheers
Cliff

Weairy
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Location: Seymour, Vic

Re: Zeroing for ETs

#8 Postby Weairy » Tue Jan 19, 2021 10:56 am

At Bendigo, they use a clay target on the stop butt. The stop butt is about 50m past the targets. So you aim at the clay target with your assumed zero for that range and your shot should be about 300-400mm below the clay. Easily observed through a scope, simple way to avoid smashing sensors. It means you're safe to shoot at the electronic and score a hit at least. But the mound is dry clay at Bendigo, so dust is nice and simple to see, too.

If you have no zero at all (freshly mounted sights, new barrel etc etc), really, you should be zeroing on a paper target or bore-sighting to start with to get somewhere within reason. I think I'd nearly cry if someone bolted a fresh scope on and tried to zero it on our ETs at 500yd straight up.
Josh Weaire
Nagambie R.C.

Tim L
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Re: Zeroing for ETs

#9 Postby Tim L » Tue Jan 19, 2021 4:08 pm

Thanks for the responses so far. I appreciate there are many options of how to achieve the aim but all have draw backs. For those that haven't shot North Queensland you probably haven't experienced mirage like we get. It's not unusual to have an aiming mark that is a grey homogenous, roughly round blob bouncing in excess of a minute. This generally follows a wet spell where the bullet catcher is either damp or covered in grass. Spotting fall of shot in these conditions is rather more difficult than may be imagined.
We then have the scope thats a full turn out. Where do those bullets go? Certainly not in the desired splash area. Sometimes the bullet vortex is visible, sometimes not.

The point here is that, yes, there are options other than a short range target. Those, however, aren't the ones I'm looking at.

All I'm after is a bit of help confirming that most, if not all, loads zeroed at 30m will be within 2 minutes by simply winding up 3 moa for 300m and 3moa for every subsequent 100m increase.

It's easy enough on Applied ballistics. Just edit the load to a 30m zero then select that load and hit trajectory. Check the table that the evation is within 2 minutes of 3, 6, 9, 12 and 18 minutes for 300, 400, 500, 600, 700 and 800m respectively.

pjifl
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Re: Zeroing for ETs

#10 Postby pjifl » Tue Jan 19, 2021 4:40 pm

The biggest problems are with people turning up with hunting rifles. Often with more or less blunt nose bullets.

It is a pity to turn them away so I know where you are coming from.

Peter Smith.

bruce moulds
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Re: Zeroing for ETs

#11 Postby bruce moulds » Tue Jan 19, 2021 8:20 pm

if people could be relied on to actually activate their brains, no discussion would be necessary on this subject.
anyone should be able to zero a rifle in such a way that a sight adjustment will put them on a target.
problem is there still does not seem to be a cure for stupid.
and when one seems to have been found, a new improved stupid rears its head.
people are just too lazy to think and do their homework, and some don't seem to want to even learn.
in fact even with zeroed rifles it is amazing the number of bullet holes, sideways and point first, in the numbers in front of the mantlet.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880
http://youtu.be/YRaRCCZjdTM

bruce moulds
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Re: Zeroing for ETs

#12 Postby bruce moulds » Wed Jan 20, 2021 8:05 am

here is a thing i have actually witnessed.
at a longer range i saw a guy bore sight a rifle prior to engaging an et.
it became apparent that the barrel was pointing directly at the target with the scope also on the target.
no attempt was made to allow for drop.
any one who has ever looked through a barrel on a rifle zeroed at longer range will attest to the fact that it is probably pointing near or above the top of the backstop.
we all have a responsibility to understand the basics of trajectory, wind deflection, etc. in relation to zero, and in doing so will realize that going to 100 and doing the foundation work is fundamenta, as is somehow establishing comeups.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

AlanF
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Re: Zeroing for ETs

#13 Postby AlanF » Wed Jan 20, 2021 8:44 am

Bruce,

We have people who've had to be helped with zeroing throughout their shooting careers. As long as they know to ask and someone is prepared to help, its fine by me. Its the over-confident ones who think they know what they're doing (and don't) who are the problem.

bruce moulds
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Re: Zeroing for ETs

#14 Postby bruce moulds » Wed Jan 20, 2021 11:23 am

yes alan.
but how do you put it to the latter group when they actually argue black and blue.
probably this thread is about having a system that works.
bruce.
"SUCH IS LIFE" Edward Kelly 11 nov 1880

http://youtu.be/YRaRCCZjdTM

AlanF
Posts: 7251
Joined: Wed Jun 15, 2005 8:22 pm
Location: Maffra, Vic

Re: Zeroing for ETs

#15 Postby AlanF » Wed Jan 20, 2021 11:58 am

bruce moulds wrote:yes alan.
but how do you put it to the latter group when they actually argue black and blue.
probably this thread is about having a system that works.
bruce.

The key is to have a competent and "firm but fair" RO. If there is a large number of offenders then you might have to consider making zeroing on a manual target compulsory with no exceptions. Its not only a target damage issue, but a safety issue.


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