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5x25x50 Zeiss HD5 sighting in oddities - need help

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Fat Dave View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fat Dave Quote  Post ReplyReply Direct Link To This Post Topic: 5x25x50 Zeiss HD5 sighting in oddities - need help
    Posted: June/14/2015 at 16:00
Hi guys,

New to the forum here and hoping someone out there can help me understand how to use my new scope mounted on a Sako A7 .308 WIN, as after yesterday I am a little confused. Scope in question is the Zeiss Conquest HD5 5x25x50 Rapid Z- 800.

Please bear with me as I try to get this down - as it's a bit of a long read.

Yesterday I went to sight in the rifle at the range.
I am using hand-loaded 150 grain Hornandy SST's, powered by 43.0 grains of IMR4895. This groups well for my Sako. The muzzle velocity (according to the Hornandy manual for this set-up is around 2600 ft/s). In New Zealand we use the metric system so muzzle velocity is @ 790 odd metres per second.

First target was at 100 metres. I set the magnification to x15. After a few shots I had a nice 3 shot group at about 1.5 cm high above the bull. Sweet I thought, let's take it out to 200 - as I reckoned with this setting I'd be smack on. Using the same x15 magnification I fired another couple of groups. Sure enough at 200 metres my shots were spot on, 2 centre bull hits even!

OK, so I was pretty happy at this stage. Let's push it out another 100 metres and see what this scope can do for me.
From the 300 metre mark I looked at the target (same size target at all ranges) and it looked mighty small. No worries I thought, I've got this super powerful scope - let's just wind her up to full x25 power and see how easy it all is.

I wound it up to full power and marvelled at the target. It looked nice and big. Easy.

Knowing that the .308 will be dropping quite a lot at 300 metres, I knew I needed to compensate for the bullet drop. Luckily the Rapid Z 800 has this covered. All I had to do was chose which reticle to use. It's at this point that the wheels started falling off.

Now, having used a Leopold LR duplex sight previously, I knew that for a 200 metre zero, at 300 metres I needed to use the next duplex 'dot' down from the main cross-hair to compensate for this drop, so I (incorrectly) assumed, the way the rapid Z was set up was similar to this.
Lining up on the 300 metre target's bulls-eye with the next reticle underneath the main one ( I believe it would be marked with a 3, as the one under that is marked with a 4), I fired. No hit on the target. I fired another 2 and still nothing. Another 3 went down range - no hits. The target is about the size of an A4 piece of paper, stuck in the middle of cardboard box which is slightly bigger. I didn't even hit the the box!

I walked up and found that all my shots were gouging huge holes into the dirt about 30 odd centimetres below the middle of the bulls-eye. 

Since I had fired my last remaining rounds I walked back to the car shaking my head and wondering what had just happened. What effect did winding up the power to a full x25 have on my perceived aim?

The Zeiss Rapid Z calculator sort of answered my questions - but entering in my (approx.) velocity data, as well as bullet type, weight and BC, the POI data displayed in their Rapid Z 800 GUI gave me figures which still didn't match what I experienced on the range.

Some figures:

My muzzle velocity is 2600 ft/sec. I have no idea what this would be @ 200 metres. According to the Rapid Z calculations I should have used the 3.5 - 4 reticle. 

Can anyone explain to me in layman's terms what I need (needed) to do to get shots on target at 300 metres?

All help appreciated. 
Cheers,

David


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rancid Coolaid Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 17:56
David,

I don't know the reticle but I always verify everything at 100 yards.  If drop from zero should be "X" mils, check that at 100 yards - or meters.  As Reagan said, "Trust, but verify."

I have yet to use a calibrated reticle that was dead on at more than about 2 points of aim.

My recommendation is you scrap the program, load up 20-30 rounds and go to the range and get actual drop with your rounds, your gun, your ammo, your environmental conditions, then all will be right as rain.

Good luck.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kickboxer Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 19:24
"Calibrated reticles" are just that… calibrated for particular environmental conditions and particular loads…
As RC said, you have to shoot in a "calibrated reticle" for your particular ammo and conditions.  And it will vary with conditions.  

However, it is a good starting point…  the programs provided by Zeiss, Swarovski, Nikon are very good and if you give them correct data, they are very close.  That never eliminates the need to verify and "recalibrate" for your particulars…  I generally put in intial data, then go to the range and write in the actuals.  Has worked well for me.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sakomato Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 19:27

You are making several mistakes

First the RapidZ 1000 is the reticle formulated specifically for the 308, but since you have the RapidZ 800, it can be made to work

Second the Conquest line is a Second Focal Plane scope.  That means that the distance between the horizontal bars on a downrange target will change with changes in the power setting.  Unlike a First Focal Plane scope where the distance between the bars on the downrange target will not change with changes in the power setting.  SO, you need to pick ONE setting for the power that will give you the best results to make your bars match downrange, and shoot at that power ONLY

Third when you use the Zeiss RapidZ calculator, you need to put in all the data and then hit the "RECOMMENDED MAGNIFICATION" and it will tell you what power to shoot at

When I put in your data in

150 Hornady SST with a BC of .415

MV 2600 fps

Vel at 200 yds 2207 fps

Sight in distance 200 yds

Elevation 500 ft

Temperature 59 degrees F

It gives you the estimated impact point for the

First line down 302 yds.

Line 4 at 407 yds

Line 5 at 508 yds

Line 6 at 606 yds

Line 7 at 703 yds

Line 8 at 797 yds


AT THE RECOMMENDED MAGNIFICATION OF 13.5 POWER

That is the way the scope is intended to work



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fat Dave Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 20:15
Thanks for the replies guys! All good advice and info.

The Zeiss Rapid Z calculator makes sense to me now - but I guess it's still up to me (the shooter) to verify the POI depending on distance and magnification. 

Yes, I'll admit up front - I made several mistakes :) 
Appreciate the time spent on replying to my post.

Thanks heaps

Cheers,
David


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fat Dave Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 20:48
by the way...

"SO, you need to pick ONE setting for the power that will give you the best results to make your bars match downrange, and shoot at that power ONLY" 

...this statement  - which makes absolute sense to me now - negates what I thought the benefits of buying a variable power scope would bring to the hunting game, that is: magnifying the target larger so it becomes easier to hit!
Again, it's my ignorance of optics in general which got me to that idea.

Appreciate the info.

David
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rancid Coolaid Quote  Post ReplyReply Direct Link To This Post Posted: June/14/2015 at 22:52
The variable is still a good thing, just be aware that the relationship of target to reticle changes as power changes.

If you want to be able to adjust based on the reticle at all power settings, you need an FFP reticle.


Glad things make more sense now.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sakomato Quote  Post ReplyReply Direct Link To This Post Posted: June/15/2015 at 17:30

Hey Dave

Next step (IMO worth what you paid for it) would be to get a chronograph and see what you are actually getting in velocity.  Then if you are a reloader you can start bumping your velocity up to get more out of the scope.

My Nosler manual lists some loads in 308 win with 150 gr bullet at 3000 fps (with Varget).  SO if you could bump your velocity up (carefully and looking for pressure signs as you go), you should be able to reach 2950 fps or so and then your recommended power setting would be 18 POWER

Much better and 18 power is plenty of magnification for seeing targets waay out there


Just sayin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fat Dave Quote  Post ReplyReply Direct Link To This Post Posted: June/15/2015 at 17:36
Hi guys,

Again, appreciate the replies. I am finding out that I should have done waaaay more thinking about variable power scopes! The FFP reticle behaviour is what I thought  the way all variable power scopes worked!

Thanks Sakomato. I will be trying to get more out of my hand-loads to push the envelope in terms of distance. The glass of this scope is great, so I will make it work for my .308 :)

Nice one.

David

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: June/16/2015 at 03:24
A first focal plane scope is also not the answer for every problem. Remember there are never always just positives. One of the negatives of a first focal is that as you down the magnification the reticle becomes very small. On hot days when you do not want high magnification due to mirage, this can be a problem.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Acker Quote  Post ReplyReply Direct Link To This Post Posted: June/16/2015 at 10:29

I personally prefer the reticle in the second plane, as a rule. In the first plane attached to the zoom as the size goes up and down with mag, can take a quite bit of the field of view at 20x. The worst was one on a Swarovski , the reticle lines looked like tree trunks. I like my reticle to stay the same size "what ever."

Then again, being old fashioned, I prefer fixed focus as most of our game, for rifle is taken from high seats and within 200 yards.


Acker.


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