sighting in target

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lonerider43
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sighting in target

#1 Postby lonerider43 » Thu Jun 13, 2019 8:38 pm

does anyone know of a sighting in target i can download for a 243 ?
a fella at the club needs to get his scope sorted.[without doing it at every range.]
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AlanF
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Re: sighting in target

#2 Postby AlanF » Thu Jun 13, 2019 10:57 pm


scott/r
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Re: sighting in target

#3 Postby scott/r » Fri Jun 14, 2019 5:45 am

www.triplej.com.au have zero targets. Go into downloads and click on Sighting. You'll find the 25 yard zero targets as a free download.
Scott.

lonerider43
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Re: sighting in target

#4 Postby lonerider43 » Fri Jun 14, 2019 7:30 am

thanks alan,ive looked at those last night,didnt find what i was after.
scott i know those ones,for 155grn 308.[i posted that link not long ago]

i was really after something more specific for the 243.but never mind.


side Q: what projectile weight should he be using in a 1/10 twist 20 or 23" barrel ? for distances from 300 to 1000 yrds.
what ever he was using last sunday,he was spraying them all over the place at 300.[more off the target than on]
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Tim L
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Re: sighting in target

#5 Postby Tim L » Fri Jun 14, 2019 7:57 am

From a 1:10 nothing.
He'll probably get away with 95gn for shorts but i doubt it will have the legs for longs. 75gn are suitable for the gun but the short barrel is likely to hinder getting the velocities required for long range accuracy.
https://bergerbullets.com/twist-rate-calculator/

With regards to zeroing targets, you'll need the projectile and velocity. If you've not got that you may as well use the 308 target.
Any ballistics app will provide the elevation, but you'll need the bullet weight and velocity to run them aswell.

lonerider43
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Re: sighting in target

#6 Postby lonerider43 » Fri Jun 14, 2019 8:16 am

thanks tim.
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Triplejim
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sighting in target

#7 Postby Triplejim » Fri Jun 14, 2019 9:38 am

Have just uploaded a 5 calibre 25m target designed for Benalla RR
http://www.triplej.com.au/pdfpages/25mTarget3.pdf
LRP gave us the velocities for the calibers, JBM for elevations and McD did the CAD
Has a centre white dot for scopes
Best to print out on A3, James

AlanF
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Re: sighting in target

#8 Postby AlanF » Fri Jun 14, 2019 1:04 pm

I think this is a great idea, but its important to know its limitations. If you have a first up shoot at the longs, and its electronic targets, then you run the risk of making your target maintenance people very unhappy if you hit cabling or a sensor because of a poorly zeroed rifle. This method will be okay out to about 700yds, but may be stretching things thereafter.

Doing some 1000yd ballistics calculations, I found that the main source of error of this method is the wide range of drop figures out there for each calibre. In 7mm for example there is approximately 7MOA difference between say a 175SMK at 2750fps and 183SMK at 3000fps. Scope height variations have a lesser but still significant effect (1/2" difference in scope height causes about 2MOA difference at 1000yd). Then you have other minor things such as the accuracy of the zero test (+/- 1/2MOA?). With the LR target being only 7MOA high at 1000yds, the chances of getting a hit from this zeroing method would I suggest be well short of 100%, particularly when you factor in all skill levels and equipment/ammo specs. Even at 800 and 900yd, it would be far from bulletproof (no pun intended)...

Being on a 300 to 1000yd range with Hexta targets we take zeroing seriously, and except for rare concessions by the RO, every shooter/rifle combination must get a hit in the black on a manual target prior to shooting on the Hextas. There was some resistance initially, but like the bolt cycle, its now become an accepted routine.

pjifl
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Re: sighting in target

#9 Postby pjifl » Fri Jun 14, 2019 3:19 pm

And people turn up with old hunting ammo in sporting rifles which often have a wider tip and so are less aerodynamic and have no idea of velocity or ballistics. They are often amazed just how poorly these bullets fly at longer distances and dont want to believe it. We do not turn them away. But we have solved the problem by always having up an old target frame which is hollow.

Used in conjunction with a good spotting scope, people just watch for hits on the backstop behind it. The hollow square concentrates the eye onto the backstop.

This depends somewhat on your backstop for visibility and sometimes it is hard to see fall of shot but on our range it works very well and has been well accepted by everyone. Highly recommended if it or some variation suits your range. I think some visitors get as much a kick shooting on it as on a target anyway. Most have never shot beyond 150y and to them these are almost 'free shots'.

I once forgot my range data record and was at a big shoot 500 miles away from home. Thankfully, we worked our way back - right back to 1200y eventually.

So I started a graph of elevation versus range and extended it - extrapolated it - every time we moved back. Got well onto target every time.

Personally I am not very interested in a sighting in target although when everyone used Army ammo it was useful. Not every range has easy access to a zero range where you can use the sighting in target. And many scoped rifles have scopes mounted at different heights. If you zero in at very short range like on a zero range this becomes another unknown factor.

If you are serious, find someone with a chrony, get MV, then use any one of many ballistic calculators knowing your bullet to construct a range table. The Chrony is also a good check on quality and consistency of loading. Know your come up between ranges. Paste it on the side of your rifle. Always record your last shoot range. Write it on a card and place it under your barrel for reference for next shoot which may be in a few month's time. And in a book as well.

Peter Smith.

lonerider43
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Re: sighting in target

#10 Postby lonerider43 » Fri Jun 14, 2019 5:04 pm

we used one of the sighting targets from triplej.this got him a 300 zero.
he used 110gn [went in side ways at 25 yrds ?] 90 gn [which shot ok] and 95 gn.
the 90's printed low compared to the 95's.
we then went after a 500 and 600 sight in.
i think he should be in the black,or at least on the target.which is still an improvement from last weekends effort.
thanks for all of your input fellas.
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Tim L
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Re: sighting in target

#11 Postby Tim L » Fri Jun 14, 2019 6:13 pm

It would be interesting to hear how you go. You never had a chance with the 110s, been there and done thst myself. The 90/95 will go ok out of a 1:10 whilst it has the speed but I suspect it will loose stability at some point.
If you think you have a 300 zero come up 6min for 500 and another 4 for 600. That should put you on paper.

bruce moulds
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Re: sighting in target

#12 Postby bruce moulds » Fri Jun 14, 2019 8:54 pm

when the 243 was introduced it came with 1:10 twist for max wt 100 gn flatbase bullets.
bruce.
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lonerider43
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Re: sighting in target

#13 Postby lonerider43 » Fri Jun 14, 2019 9:12 pm

he will be shooting the 500 this sunday.
it will be interesting.
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bsouthernau
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Re: sighting in target

#14 Postby bsouthernau » Sat Jun 15, 2019 9:42 am

Tim L wrote: The 90/95 will go ok out of a 1:10 whilst it has the speed but I suspect it will loose stability at some point.



Unless I've got this wrong - which HAS happened in the past - the bullet becomes more stable as it slows down in flight.

Tim L
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Re: sighting in target

#15 Postby Tim L » Sat Jun 15, 2019 12:46 pm

bsouthernau wrote:
Tim L wrote: The 90/95 will go ok out of a 1:10 whilst it has the speed but I suspect it will loose stability at some point.



Unless I've got this wrong - which HAS happened in the past - the bullet becomes more stable as it slows down in flight.

As I understand it , that is dependant on spin rate being suitable from the start. Spin will slow more slowly than the bullets forward motion will, so the bullet remains stable. I don't know if it becomes 'more' stable as the ratio of spin to forward motion increases but I guess it's possible.
If, however, the spin is not fast enough when it leaves the muzzle it can reduce to the point the bullet becomes unstable in flight.
The 1:10 can't stabalise a 110 at all, it can start a 95 grain off stable, but only just. As the spin rate decays the stability fails.

I too could be wrong but this is how it's been exained to me.


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