Author Topic: Blerk's Progress  (Read 43033 times)

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Offline IceBlerk

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Re: Blerk's Progress
« Reply #660 on: August 31, 2018, 08:25:38 AM »
I think I've got it!

It's because the trajectory of the pellet is an arc and 25yards is on one side of its "zenith" and 10yards on the other.

As one dials the vertical alignment of the scope the sight line through the arc may change where they intercept and they two points may eventually touch (infinitely close to each other) or the primary may drop out of range (infinitely far from each other) but they can't cross over each other.

And now I've thought about it a little and I'm beginning to doubt myself again.
..........so I packed up and went to the pub.

Offline Gambo

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Re: Blerk's Progress
« Reply #661 on: September 01, 2018, 02:24:02 PM »
I think I get what your asking Blerky...........

The way to check is to put targets out at various ranges to test the pellet arc, plus the primary and secondary zeros. Doing that with then confirm/disprove the questions/doubts in your mind.

Here's another curve ball to consider.....

It is possible to set the scope/rifle/pellet combo up so the 'apogee' (the very peak of the pellet's arc) is the zero at your chosen range. If you did that, then you'd never have to aim low no matter what the range, as the pellet will never rise about the crosshair's horizontal plane.


Offline IceBlerk

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Re: Blerk's Progress
« Reply #662 on: September 03, 2018, 01:13:37 PM »
I think I get what your asking Blerky...........

The way to check is to put targets out at various ranges to test the pellet arc, plus the primary and secondary zeros. Doing that with then confirm/disprove the questions/doubts in your mind.

Yes, I understand that and see the sense in the practical results of the test. Totally.

Here's another curve ball to consider.....

It is possible to set the scope/rifle/pellet combo up so the 'apogee' (the very peak of the pellet's arc) is the zero at your chosen range. If you did that, then you'd never have to aim low no matter what the range, as the pellet will never rise about the crosshair's horizontal plane.

Ah! I think this might be the answer to why I'm having trouble with getting this into my brain. What you say makes sense.

Sooooooo .................. if a scope had been set up to hit the zero at the apogee of the arc (i.e. BOTH primary AND secondary zeros are at the same point) how would you split them? Would you dial the scope's POI up or down? Or would it be EITHER?!?!?!?!?
..........so I packed up and went to the pub.

Offline IceBlerk

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Re: Blerk's Progress
« Reply #663 on: September 03, 2018, 01:24:45 PM »
I've just had a think and drawn it on paper and the answer is "down", yes?

Down ............. because you're lowering the line of sight to cross the arc.

But I think that's going to push the primary zero away.

So how would it stay at 25yards (say) and PULL the secondary zero towards you? Surely you wouldn't have to fiddle with mounts.

Damn! I'm beginning to think that I've still not understood it!
..........so I packed up and went to the pub.

Offline Gambo

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Re: Blerk's Progress
« Reply #664 on: September 04, 2018, 11:36:31 PM »
if a scope had been set up to hit the zero at the apogee of the arc (i.e. BOTH primary AND secondary zeros are at the same point) how would you split them?

You wouldn't/couldn't split them....coz they'd both be at the same point.



With regard to your other question............

Surely you wouldn't have to fiddle with mounts.

The pellet's trajectory arc will be the same every shot (if the same pellets and power is used)....so the only way to get the primary and secondary zeros to change (apart from zeroing at a different range)......is to alter the height of the scope in relation to the barrel, ie, put the scope in lower or higher mounts (depending on what you want to achieve). Doing this will then get a different aspect/view of the pellet's flight curve.

Make sense Blerkster? ???

Offline IceBlerk

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Re: Blerk's Progress
« Reply #665 on: September 05, 2018, 01:54:45 PM »
Make sense Blerkster? ???

I think I have it sorted out in my head again.

I've drawn lines of sight, trajectories and "horizons" and finally I think I realise that you can't push the secondary zero beyond the apogee of the pellet's path.

When one thinks about it it's almost .................. simples!
..........so I packed up and went to the pub.