GTA

Target Shooting Matches, Discussion & Events => Field Target Gates => Topic started by: Scotchmo on November 12, 2018, 07:54:44 PM

Title: Optimal scope height study
Post by: Scotchmo on November 12, 2018, 07:54:44 PM
Typically, I have mounted my scopes as low as possible. We have tended to have a lot of 3/8” targets at Western GP matches, and by necessity, those targets tend to be set at fairly close distances. High scopes can greatly exacerbate ranging errors for those close targets. Lately I have gone to slightly bigger scopes mounted slightly higher. I know that will help some of my longer shots so it should make up for an occasional miss on the closer 3/8” targets.

When you look around at other shooter's equipment, you'll see very high scopes, especially among some of the WFTF shooters. I know the World match WFTF courses don't have 3/8” reduced targets, and the WFTF course rules allow only a few of the 1” (25mm) and 0.59” (15mm) targets on any given course. So you will never see a close target with a very high degree of difficulty at a World match. Most of the targets are full size 1.575” (40mm) and they tend to set them farther out.

I'm planning on shooting in the 2019 WFTF world match and decided to look into some changes to my FT setup. One of those possible changes would be scope height. I used a 2.3” high scope (high for me) this last season. But I see others with much higher scopes.

What is the optimum scope height? The empirical evidence suggests that for WFTF, it's certainly higher than 2.3”, so I just got some higher mounts and am now at 2.6”. That did not seem very scientific. I figured there must be a way to quantify it. The hit probability of any given target is based on a few factors. One of those factors is ranging error. Scope height determines at what distances ranging errors are most detrimental. Targets near your zero are more tolerant of ranging errors. I decided to keep it simple to start and determine targets distances vs scope height for typical field target courses when shooting at 12fpe. Whenever you get away from your zero, you need to click (or holdover) more. Those distances with more clicks are more subject to ranging errors.

I made a spreadsheet where I could input all the target distances of an FT course. It takes scope height, and pellet velocity and BC, and calculates the amount of clicks (holdover) at each target, and totals those clicks for the whole course. More clicks means more potential errors from mis-ranging. For any given course, I can very the scope height and look for the height that yields the lowest  total clicks for the entire match.

The results were interesting.

The trajectory parameters were 795fps and .023 BC. For a typical AAFTA GP course (Western States), the spreadsheet shows an optimal scope height of 2.0”.

Last year, our club set a WFTF legal course for our GP. Though we did use the maximum number of 15mm and 25mm reduced targets that WFTF allows. The optimal scope height for that course was 2.1”.

I also input the three World courses from 2018 Poland.
White course – 3.6” optimal scope height
Blue course – 3.8” optimal cope height
Black course – 2.8” optimal scope height

The Black course had a lot more reduced targets than the White and Blue courses. The strange thing is that all the courses had more reducers than are allowed by the published WFTF course rules. I don't think more reduced targets is a bad thing, but it is bad when the course is not what is specified by the rules.

I now have a 2.6” high scope vs the 2.3” high scope that I used all off last year. 2.6”should be a better compromise for the AAFTA GP circuit and the Worlds match. Though probably a little low for a typical Worlds course. I'm just not ready to go with a 3+” high scope.

I know that you can't necessarily rely on the course rules for target size, visibility, distance, etc. Some times the shooter has recourse when they encounter an illegally placed target, other times they don't. It happens in the USA and at the Worlds. So best to be prepared.
Title: Re: Optimal scope height study
Post by: Motorhead on November 12, 2018, 09:05:49 PM
Even tho we shoot smaller KZ's up close more so than the Europeans,  I'm still of the mind set that the advantages of trajectory arc correction being somewhat flatter further out with high scope mounting, i simply am NOT willing to have the correction in close so critical doing so.  After 3 years now shooting .20 caliber at the 790's velocity which is similar to WFTF 12 ft lb speeds ( and trajectory profile too ) have had No Problems dropping into the KZ on far targets using a SH of 1.8" .... go figure being we've been ranging at 12x for 2 season and 16x in 2018.  With the ranging capability of the high mag scopes allowed in WFTF, WHY CHANGE WHAT YOUR ACCUSTOMED TOO ???  and just take advantage to superior ranging you will have at higher magnification and shoot how you know how too !!

JMO ...
Scott 
Title: Re: Optimal scope height study
Post by: Scotchmo on November 12, 2018, 11:44:30 PM
Motorhead,

I have a similar aversion to high scopes. Doing what I'm accustomed to could work. But I am going to the world's next year. And the courses will likely be different then I'm accustomed to. So I am considering some changes.

I have been ranging at 24x for most matches the last 4 years. Better than 12x or 16x but still not ideal, especially when it gets windy.

In the past, most of my guns have had a scope height of 1.7" to 2.1". This last year, 2.3" has not been a problem for close shots, especially when the smallest is .59" (15mm). I'll try 2.6" next, but I'll switch back if it doesn't work out.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 12, 2018, 11:58:33 PM
Motorhead,
I ran the following through my spreadsheet:
795fps
.035 BC

Using the course layout from a Western States GP match, the optimal scope height ends up being 1.8" . That's probably not a coincidence that you like 1.8" .
Title: Re: Optimal scope height study
Post by: gokidd on November 13, 2018, 11:14:47 AM
... and then there is the dreaded "I forgot after I shot that close target and was one full turret rotation wrong for the next lane"
Danggit.
It's tough being forgetful.
W(f)TF!!

Thank you for that info, Scott H. I always appreciate both your science and your willingness to share.
B
Title: Re: Optimal scope height study
Post by: regularguy11B on November 13, 2018, 11:24:45 AM
So, you can shoot WFTF HFT with 16X now?
Title: Re: Optimal scope height study
Post by: nced on November 13, 2018, 11:48:14 AM
So, you can shoot WFTF HFT with 16X now?
WFTF has no scope power limit and it also aliows "clicking on".

HFT however has a 16x max power setting (as of the past year) but "clicking on" isn't allowed.

Here is the 2018 AAFTA Handbook...........
http://www.aafta.org/Assets/handbook/2018/AAFTA_Handbook_2018.pdf (http://www.aafta.org/Assets/handbook/2018/AAFTA_Handbook_2018.pdf)
Title: Re: Optimal scope height study
Post by: Motorhead on November 13, 2018, 12:11:58 PM
So, you can shoot WFTF HFT with 16X now?

WFTF along with OPEN class are unlimited on X magnification. ( Can shoot holdover or clicking )
HUNTER classes had been at a 12X limit until the 2018 season where the limit was raised to 16x ( Can ONLY shoot holdover .. NO clicking allowed )
Title: Re: Optimal scope height study
Post by: regularguy11B on November 13, 2018, 12:16:31 PM
I was just looking at WFTF rules and I could not find WFTF rules specific to HFT.  Gonna check that kink out right now.  Thanks Ed.
Title: Re: Optimal scope height study
Post by: regularguy11B on November 13, 2018, 12:17:07 PM
So, you can shoot WFTF HFT with 16X now?

WFTF along with OPEN class are unlimited on X magnification. ( Can shoot holdover or clicking )
HUNTER classes had been at a 12X limit until the 2018 season where the limit was raised to 16x ( Can ONLY shoot holdover .. NO clicking allowed )

Thanks
Title: Re: Optimal scope height study
Post by: Motorhead on November 13, 2018, 12:36:54 PM
I was just looking at WFTF rules and I could not find WFTF rules specific to HFT.  Gonna check that kink out right now.  Thanks Ed.

There is NO WFTF / Hunter class ... they are SEPARATE classes entirely having there own specific rules ... tho shoot the same course here in the USA
Title: Re: Optimal scope height study
Post by: DRAGON64 on November 13, 2018, 01:50:05 PM
When you are talking about scope height, are you referring to center line of scope in relation to bore?  I recently picked up a 60mm objective scope, and are currently trying to figure what I would need in the way of scope rings for proper scope height.  I too will be shooting WFTF rules here stateside.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 13, 2018, 05:03:10 PM
So, you can shoot WFTF HFT with 16X now?

WFTF HFT?

No such thing. But there is a WHFT (World Hunter Field Target), and they have no magnification limit for scopes. Though I'm only aware of one club in the USA that has HFT matches (Heflin, Alabama). That type of course would favor a low mounted scope.

AAFTA Hunter Division is not really HFT, though many in the USA mistakenly call it HFT.

HFT - no scope limit
AAFTA Hunter Division - 16x scope limit

https://www.whfto.com/ (https://www.whfto.com/)
https://www.facebook.com/whfto/ (https://www.facebook.com/whfto/)
Title: Re: Optimal scope height study
Post by: Scotchmo on November 13, 2018, 05:09:15 PM
When you are talking about scope height, are you referring to center line of scope in relation to bore?  I recently picked up a 60mm objective scope, and are currently trying to figure what I would need in the way of scope rings for proper scope height.  I too will be shooting WFTF rules here stateside.

The 12fpe WFTF limit will have some bearing on scope height. The very high scopes are not really needed on most USA courses. At USA AAFTA matches, you will see more close targets, and they will be more difficult (0.375" for AAFTA vs 0.59" for WFTF). The course layout has even more affect on optimal scope height than does the power level (12fpe vs 20fpe).

You'll sometimes need higher scope rings to clear the large objectives. On most USA courses, about 2" - 2.1" high should be near optimal.
Title: Re: Optimal scope height study
Post by: 22Jim on November 16, 2018, 01:01:05 PM
The 12fpe WFTF limit will have some bearing on scope height. The very high scopes are not really needed on most USA courses. At USA AAFTA matches, you will see more close targets, and they will be more difficult (0.375" for AAFTA vs 0.59" for WFTF). The course layout has even more affect on optimal scope height than does the power level (12fpe vs 20fpe).

I see why you are researching this now. I looked at the course details from Poland and see where scope height could help pick up a couple of points over the course of the match. 89 of 150 targets were over 40 yards, only 24 targets were under 30 yards and 11 of those were forced position. The long game appears to be everything in Euro WFTF matches.

I really like your method of evaluating optimum scope height. I never gave it much thought as I always favored the lowest position I could get which on my competition rifles was always between 1.8 and 2.1 inches. Based on your analysis that seems to be optimal for US FT courses.

Thanks,
Jim in Sacramento
Title: Re: Optimal scope height study
Post by: Scotchmo on November 16, 2018, 05:17:32 PM
...
I really like your method of evaluating optimum scope height. I never gave it much thought as I always favored the lowest position I could get which on my competition rifles was always between 1.8 and 2.1 inches. Based on your analysis that seems to be optimal for US FT courses.

Thanks,
Jim in Sacramento

880fps with AA/JSB heavies (10.3gr/.031 BC) on a typical Western AAFTA course, it ends up as 1.5" high. Hard to do with most scopes/mounts, so lowest height will likely be determined by objective size and available mounts. My 18fpe Marauder is at 1.72" scope height.
Title: Re: Optimal scope height study
Post by: HectorMedina on November 17, 2018, 02:36:47 PM
Scvott;

Very interesting, but it begs a question:

WHERE are you measuring the "height". żAre we talking SCOPE height? OR żAre we talking LOS height?

PP Calc uses LOS height, so it is measured/calculated/corrected to the muzzle.

I find that 2.5" to 2.6" at the saddle is a good height, as the BALANCE of the gun is more manageable. Going to 3" and more makes my gun feel "tippy" and that is more important than the theoretical optimum scope height.

JMHO


HM
Title: Re: Optimal scope height study
Post by: regularguy11B on November 17, 2018, 03:15:54 PM
I am highly opinionated when it comes to scope height, especially on a springer.  Especially for someone that has not/does not compete.  For me, the lower the better.  Will be watching this thread closely! 
Title: Re: Optimal scope height study
Post by: Greg5850 on November 17, 2018, 03:40:21 PM
My scope is 2.6 in high.  That’s from center barrel to center scope.  Part of the equation for me is a comfortable head position, and as Hector said “ not too “tippy”.  Some of the Brits experimenting with very high scopes have come back down a bit.

Greg
Title: Re: Optimal scope height study
Post by: Scotchmo on November 17, 2018, 11:54:31 PM
Scvott;

Very interesting, but it begs a question:

WHERE are you measuring the "height". żAre we talking SCOPE height? OR żAre we talking LOS height?

PP Calc uses LOS height, so it is measured/calculated/corrected to the muzzle.

I find that 2.5" to 2.6" at the saddle is a good height, as the BALANCE of the gun is more manageable. Going to 3" and more makes my gun feel "tippy" and that is more important than the theoretical optimum scope height.

JMHO


HM

I measure the scope height at the scope (at the erector tube gimbal to be exact), but I do correct for the scope-base (distance from gimbal to muzzle crown). Projectile drop is calculated from the muzzle crown to the target. And target distance is measured from the gimbal to the target.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 17, 2018, 11:55:24 PM
My scope is 2.6 in high.  That’s from center barrel to center scope.  Part of the equation for me is a comfortable head position, and as Hector said “ not too “tippy”.  Some of the Brits experimenting with very high scopes have come back down a bit.

Greg

2.6" is looking good.
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 18, 2018, 04:58:15 AM
Looking at the fx impact. That's gotta be around 3"+. People are taking championships and 150yd shots without much of an issue.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 18, 2018, 08:06:08 PM
Looking at the fx impact. That's gotta be around 3"+. People are taking championships and 150yd shots without much of an issue.

150 yards is way beyond field target distances.

If shooting in a competition that has a single predetermined target distance, trajectory vs scope height is not an issue.
Title: Re: Optimal scope height study
Post by: regularguy11B on November 18, 2018, 09:21:17 PM
Looking at the fx impact. That's gotta be around 3"+. People are taking championships and 150yd shots without much of an issue.

Tall scopes don't really show their disadvantages at long range.  Close range, and vertical shots, you begin to see why a hunter is better off with a low scope.  If your nearest shot is 20 yards, it won't matter.  Like shooting prarie dogs or something.  But hunting small game, you are typically looking at 30-40 yards max and often around 10 yards or so on squirrels and cottontails.  Plus the shots at tree squirrels...  let's just say I've never felt handicapped by open sights.  They sit low to the bore and are crystal clear.
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 06:13:10 PM
I hear ya guys. Just saying. Low bore height isn't the cat's meow. As far as optimal. I don't know if there is such a thing, unless you dedicate a rifle for certain purposes.
Title: Re: Optimal scope height study
Post by: regularguy11B on November 19, 2018, 06:19:36 PM
I hear ya guys. Just saying. Low bore height isn't the cat's meow. As far as optimal. I don't know if there is such a thing, unless you dedicate a rifle for certain purposes.

If you could get the features and clarity of your favorite scope with a large objective, in a package lower to the bore, would you take it?

Other than long range shots on vermin, or maximizing the use of your point blank range in competition, in my humble opinion low bore height IS the cat's meow.

Plenty of large obj scopes cut out low to the bore btw, but typically on the high end.
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 06:33:31 PM
Ok. The 'other than' part of paragraph says what I'm talking about. And EBR guys would disagree with you from what I've gathered.

Shooting p dawgs with high scope it was nice to be able to not change any scope setting from 30-70y to nail the suckers before they move.

But hey, don't be mad at me. Just joining the conversation  ;)
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 06:35:00 PM
I DO run every PB rifle i have with ultra low scope height. You prob know why.
Title: Re: Optimal scope height study
Post by: regularguy11B on November 19, 2018, 06:56:41 PM
I'm not mad, I'm just havin' fun.  If I were not sidleined right now, I'd spend a lot less time on the forum and a lot more time putting meat in the freezer

Have not filled a single tag this year.  Haven't even been in the woods since the season started, and missed most of the spawn this year too.  I want a deer so bad I can literally taste it.  Would kill to have some fresh catfish too.
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 07:00:46 PM
Right on. I just bought 22 acres near Canadian border. So much sign, it was ridiculous. I went there on opening day and nothing. I think they were higher up the mountain. Good luck landing something!
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 07:07:32 PM
I was out in Fayetteville about twenty years ago. My back yard was literally ft Bragg. Now my back yard is literally JBLM. Go figure.
Title: Re: Optimal scope height study
Post by: regularguy11B on November 19, 2018, 07:27:59 PM
I love Bragg.  It is a shame how many pass theough here and never experience the hunting or especially the fishing.  I caught all my PR catfish here and broke it several times.  Daughters 1st largemouth bass is bigger than my PR.  She caught it in the little pond off Butner road... not sure if that was here back then.  McFayden Pond.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 19, 2018, 07:30:20 PM
I hear ya guys. Just saying. Low bore height isn't the cat's meow. As far as optimal. I don't know if there is such a thing, unless you dedicate a rifle for certain purposes.

This study was more for a dedicated Field Target rifle. Currently using it to explore the "optimal" for rifle dedicated to a single FT class (WFTF). And maybe to a single type of course (Worlds).
Title: Re: Optimal scope height study
Post by: ToRmEnToR on November 19, 2018, 09:42:40 PM
The D48 I compete HFT with it's 2.38 height. Not WFTF but i get it.
Title: Re: Optimal scope height study
Post by: Motorhead on November 19, 2018, 11:26:32 PM
Scott,
In the last few days been fooling around with my WFTF rig after stacking some risers under the mounts until at @ 2.8"
The first thing noticed ( yea I'm long necked ) is a slightly less slumped / cramped shooting position while in "Deadman" .... which was a relief being a non Yoga guy  :P

Second was CANT .. O'my what a critical exercise that turned into finding very quickly that the increase in scope height to bore C/L would really skew pellets left / right if the bubble level was not dead nutz level when shot was taken  :o

So for at least me coming from Hunter class and low scope position stabilized via seat / sticks ... now shooting Deadman being the only way found to get as stable of sight picture, Wierd azz scope view now being sideways, no cheek weld, gun elevated via hamster resting on body parts, high X mag optics etc  :-\ :-\

THERE IS SO MUCH NEEDING TO BE ADDRESSED PRIOR TO TAKING SHOT NOW ... compounded by being in constant battle with keeping "LEVEL" really is a challenge that eats up time and wears on my concentration efforts.

I'm finding / thinking I would rather be slightly more slumped over having the lower scope height and ease in keeping level over some small trajectory advantage of the higher position.

Jury's still out tho and  just sharing personal observations on said subject  as i too explore this subject.

Scott S
Title: Re: Optimal scope height study
Post by: Scotchmo on November 19, 2018, 11:58:39 PM
Scott,
In the last few days been fooling around with my WFTF rig after stacking some risers under the mounts until at @ 2.8"
The first thing noticed ( yea I'm long necked ) is a slightly less slumped / cramped shooting position while in "Deadman" .... which was a relief being a non Yoga guy  :P

Second was CANT .. O'my what a critical exercise that turned into finding very quickly that the increase in scope height to bore C/L would really skew pellets left / right if the bubble level was not dead nutz level when shot was taken  :o

So for at least me coming from Hunter class and low scope position stabilized via seat / sticks ... now shooting Deadman being the only way found to get as stable of sight picture, Wierd azz scope view now being sideways, no cheek weld, gun elevated via hamster resting on body parts, high X mag optics etc  :-\ :-\

THERE IS SO MUCH NEEDING TO BE ADDRESSED PRIOR TO TAKING SHOT NOW ... compounded by being in constant battle with keeping "LEVEL" really is a challenge that eats up time and wears on my concentration efforts.

I'm finding / thinking I would rather be slightly more slumped over having the lower scope height and ease in keeping level over some small trajectory advantage of the higher position.

Jury's still out tho and  just sharing personal observations on said subject  as i too explore this subject.

Scott S

If your bubble is not level, the pellet will go left or right on far shots, especially with a slow/low-bc projectile that has lots of drop at that distance. The amount of "skew" is dependent on pellet drop and degrees of cant. Scope height does not enter into the equation. As Hector said earlier - a high scope is more "tippy", so it is harder to hold the rifle vertical. Compound that with a high hamster, and the rifle no longer wants to rest naturally in the vertical position.

That's one reason why I prefer everything as low as possible for whatever shot will allow it. I'm only looking into a higher scope as a means to shift my point blank range farther out. And even that is only beneficial on some courses. So I decided on a compromise of 2.6" for now.

Yes- same as you. Any time I start using a new position, new equipment, etc.  it seems I need to address so much more. First inclination is just go back to what I was accustomed to. But it gets easier once it becomes my most used position. Bucket and sticks, prone, and the yoga position, all took some getting used to. Whatever position that I use the most always becomes my preferred position, and it does not seem to matter what the position is.

I don't think you need a 2.8" high scope for WFTF Division on AAFTA courses. 2" to 2.5" is probably better.
Title: Re: Optimal scope height study
Post by: HectorMedina on November 21, 2018, 01:02:25 PM
Thanks, Scott H for the reply and the discussion.
It has been an interesting discussion, specially because in the end, I THINK, the conclusion is that the SHOOTABILITY of the rig is more important than the technological advantages of some aspects of it.
Of course, shootability improves with practice, LOL! This will probably be noticed by Scott S. soon.

Keep well and shoot straight!


HM

Title: Re: Optimal scope height study
Post by: regularguy11B on November 21, 2018, 01:52:49 PM
Scott,
In the last few days been fooling around with my WFTF rig after stacking some risers under the mounts until at @ 2.8"
The first thing noticed ( yea I'm long necked ) is a slightly less slumped / cramped shooting position while in "Deadman" .... which was a relief being a non Yoga guy  :P

Second was CANT .. O'my what a critical exercise that turned into finding very quickly that the increase in scope height to bore C/L would really skew pellets left / right if the bubble level was not dead nutz level when shot was taken  :o

So for at least me coming from Hunter class and low scope position stabilized via seat / sticks ... now shooting Deadman being the only way found to get as stable of sight picture, Wierd azz scope view now being sideways, no cheek weld, gun elevated via hamster resting on body parts, high X mag optics etc  :-\ :-\

THERE IS SO MUCH NEEDING TO BE ADDRESSED PRIOR TO TAKING SHOT NOW ... compounded by being in constant battle with keeping "LEVEL" really is a challenge that eats up time and wears on my concentration efforts.

I'm finding / thinking I would rather be slightly more slumped over having the lower scope height and ease in keeping level over some small trajectory advantage of the higher position.

Jury's still out tho and  just sharing personal observations on said subject  as i too explore this subject.

Scott S

If your bubble is not level, the pellet will go left or right on far shots, especially with a slow/low-bc projectile that has lots of drop at that distance. The amount of "skew" is dependent on pellet drop and degrees of cant. Scope height does not enter into the equation. As Hector said earlier - a high scope is more "tippy", so it is harder to hold the rifle vertical. Compound that with a high hamster, and the rifle no longer wants to rest naturally in the vertical position.

That's one reason why I prefer everything as low as possible for whatever shot will allow it. I'm only looking into a higher scope as a means to shift my point blank range farther out. And even that is only beneficial on some courses. So I decided on a compromise of 2.6" for now.

Yes- same as you. Any time I start using a new position, new equipment, etc.  it seems I need to address so much more. First inclination is just go back to what I was accustomed to. But it gets easier once it becomes my most used position. Bucket and sticks, prone, and the yoga position, all took some getting used to. Whatever position that I use the most always becomes my preferred position, and it does not seem to matter what the position is.

I don't think you need a 2.8" high scope for WFTF Division on AAFTA courses. 2" to 2.5" is probably better.

With greater distance between the bore and the line of sight, does it not move the rifle further laterally from the line of sight at a given amount of cant?
Title: Re: Optimal scope height study
Post by: Motorhead on November 21, 2018, 02:17:46 PM
Scott,
In the last few days been fooling around with my WFTF rig after stacking some risers under the mounts until at @ 2.8"
The first thing noticed ( yea I'm long necked ) is a slightly less slumped / cramped shooting position while in "Deadman" .... which was a relief being a non Yoga guy  :P

Second was CANT .. O'my what a critical exercise that turned into finding very quickly that the increase in scope height to bore C/L would really skew pellets left / right if the bubble level was not dead nutz level when shot was taken  :o

So for at least me coming from Hunter class and low scope position stabilized via seat / sticks ... now shooting Deadman being the only way found to get as stable of sight picture, Wierd azz scope view now being sideways, no cheek weld, gun elevated via hamster resting on body parts, high X mag optics etc  :-\ :-\

THERE IS SO MUCH NEEDING TO BE ADDRESSED PRIOR TO TAKING SHOT NOW ... compounded by being in constant battle with keeping "LEVEL" really is a challenge that eats up time and wears on my concentration efforts.

I'm finding / thinking I would rather be slightly more slumped over having the lower scope height and ease in keeping level over some small trajectory advantage of the higher position.

Jury's still out tho and  just sharing personal observations on said subject  as i too explore this subject.

Scott S

If your bubble is not level, the pellet will go left or right on far shots, especially with a slow/low-bc projectile that has lots of drop at that distance. The amount of "skew" is dependent on pellet drop and degrees of cant. Scope height does not enter into the equation. As Hector said earlier - a high scope is more "tippy", so it is harder to hold the rifle vertical. Compound that with a high hamster, and the rifle no longer wants to rest naturally in the vertical position.

That's one reason why I prefer everything as low as possible for whatever shot will allow it. I'm only looking into a higher scope as a means to shift my point blank range farther out. And even that is only beneficial on some courses. So I decided on a compromise of 2.6" for now.

Yes- same as you. Any time I start using a new position, new equipment, etc.  it seems I need to address so much more. First inclination is just go back to what I was accustomed to. But it gets easier once it becomes my most used position. Bucket and sticks, prone, and the yoga position, all took some getting used to. Whatever position that I use the most always becomes my preferred position, and it does not seem to matter what the position is.

I don't think you need a 2.8" high scope for WFTF Division on AAFTA courses. 2" to 2.5" is probably better.

With greater distance between the bore and the line of sight, does it not move the rifle further laterally from the line of sight at a given amount of cant?

Pretty sure this is true and the "why for" of my statement .. just the slightest cant the POI  much more so shifted sideways much greater than the same cant dd with my more typical  lower "hunter scope height"
Either that or I'm nutz (https://www.bmwlt.com/forums/images/smilies/crazy.gif)
Title: Re: Optimal scope height study
Post by: regularguy11B on November 21, 2018, 02:46:46 PM
I agree.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 21, 2018, 03:53:00 PM

With greater distance between the bore and the line of sight, does it not move the rifle further laterally from the line of sight at a given amount of cant?

No. You are still aiming at the same point.
Title: Re: Optimal scope height study
Post by: Motorhead on November 21, 2018, 04:01:46 PM

With greater distance between the bore and the line of sight, does it not move the rifle further laterally from the line of sight at a given amount of cant?

No. You are still aiming at the same point.

That makes no sense .... If the bore is ABSOLUTELY under the Cross hair on the vertical plane we have no cant .. this a given.  As the distance between bore C/L and Scope C/L increase, so increases the horizontal shift distance for the same amount of cant angle.

Now that said I'm admittedly NOT an engineer and schooled in angles / trig & such   :-[
Title: Re: Optimal scope height study
Post by: Scotchmo on November 21, 2018, 04:07:01 PM
Pretty sure this is true and the "why for" of my statement .. just the slightest cant the POI  much more so shifted sideways much greater than the same cant dd with my more typical  lower "hunter scope height"
Either that or I'm nutz (https://www.bmwlt.com/forums/images/smilies/crazy.gif)

You're "nutz"  ;D -

Scope height does not enter into the equation. It’s strictly a function of pellet-drop and cant-angle.

horizontal shift = drop x sin(cant_angle)

vertical shift = drop x (1-cos(cant_angle))

If you plot the cant errors at all angles, you get this:
(http://www.scotthull.us/photos/Misc/CANT-AXIS-01.JPG)

The pellet could care less how high your scope is mounted. It will go where it's pointed.

A "what if" experiment (just think it through - no need to actually perform a physical experiment):

You have one gun with two scopes mounted on it. One at 2" high and one at 6" high. Both scopes are zeroed at 50 yards. Lock the gun down in a bench rest aimed at a 50 yard target, while also canted 30 degrees to the right. The gun will not be moved for the entire test. You can look through either scope and see the crosshair on the bullseye. Fire a pellet at the target without looking through the scope. Then do it while looking through the 2" high scope and also while looking through the 6" high scope. It will hit right and slightly low. At the same point POI, every time.

It does not matter which scope you are looking through, or how high it is mounted. The amount of gun cant error is determined by the amount of drop and the degree of cant. It "can't" be any other way.

Trigonometry and geometry are two of my specialties. Calculus - not so much. This is a fairly straightforward geometry/trig problem, where the result can go against one's intuition.
Title: Re: Optimal scope height study
Post by: Motorhead on November 21, 2018, 04:23:40 PM
Thank you Scott ... so my guess is that while shooting WFTF, the difficulty in maintaining "Level" is whats killing me.  When shooting hunter I live & die by my level and always paid MUCH attention to it prior to each shot.

I'll stay with nutz ... 60 years now it has served me pretty well  ;D
Title: Re: Optimal scope height study
Post by: regularguy11B on November 21, 2018, 04:26:06 PM
Brother that is a great illustration, but where is height over bore taken into consideration?  Also, since when do you take all of your shots at the same range you are zeroed from?

It is hard for me to sit in my chair and question someone like you on that, but it definitely makes a difference.  Especially in closer or our further than your PBR.

And with 6" height over bore?  Vs 2.5"?? That doubles the distance of poa from poi.  No way that it doesn't matter.  Might not be as big a deal at the range you are zeroed, but for sure it will matter at different ranges.

And finally,  I have fired a lot from odd and awkward positions in my life.  I can tell you for a fact, if you have to shoot laying on your side, your POI changes drastically.

All I am trying to say is, height over bore matters, relative to the angle of the shot. For sure it mattere outside of your PBR and matters more as the amount if cant increases.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 21, 2018, 06:25:32 PM
Brother that is a great illustration, but where is height over bore taken into consideration?  Also, since when do you take all of your shots at the same range you are zeroed from?

It is hard for me to sit in my chair and question someone like you on that, but it definitely makes a difference.  Especially in closer or our further than your PBR.

And with 6" height over bore?  Vs 2.5"?? That doubles the distance of poa from poi.  No way that it doesn't matter.  Might not be as big a deal at the range you are zeroed, but for sure it will matter at different ranges.

And finally,  I have fired a lot from odd and awkward positions in my life.  I can tell you for a fact, if you have to shoot laying on your side, your POI changes drastically.

All I am trying to say is, height over bore matters, relative to the angle of the shot. For sure it mattere outside of your PBR and matters more as the amount if cant increases.

"...great illustration, but where is height over bore taken into consideration?..."

It's not taken into consideration because scope height does not enter to the equation for pellet drop. From where you choose to spectate the shot does not affect the pellet path.


"...Also, since when do you take all of your shots at the same range you are zeroed from?..."


My POA (Point Of Aim) always matches my intended POI (Point Of Impact). It does not matter if I'm clicking to rezero, or if I'm using a different mil-dot as my "zero". A stadia type reticle has multiple aim points, therefore multiple zeros.

Here is a special situation, and maybe it is what you are talking about:

Aiming high vs using your mil-dots or clicking

Let's say that you are shooting at a very close target. But all you have is a target dot reticle (only one zero point). You are going to make the shot without clicking. You will need significant "holdover". In this special instance, you will not be aiming at the bullseye, you will be aiming above the target. For a low scope, the POI might be 1" below the reticle dot. For a higher scope the POI might be 2" below the reticle dot.  You will aim 1" above the bulleseye when using the low scope, and 2" above when using the high scope. And that will work. But now let's also say that the LOS (Line Of Sight) is canted 30 degree for both shots. Canting now includes an additional error that is related to scope height. You will get the drop related cant error (from gravity), but you will also get a LOS error. Your POA is now canted with respect to the bullseye, so you will get an additional error directly related to scope height. For a close target, the high scope will produce more error. For far targets, it's less of a problem. But for those far targets, the lower scope will have slightly more error. This additional error does not care about pellet drop, it cares about POI from trajectory apex.

If you click, or use "holdover" points on the reticle, than scope height does not determine the degree of cant error. However, if you aim for a higher point on the target (not the bullseye), you are also canting the LOS, so you will have two types of cant induced errors present. Gun cant AND LOS cant.
Title: Re: Optimal scope height study
Post by: nced on November 21, 2018, 07:36:16 PM
Brother that is a great illustration, but where is height over bore taken into consideration?  Also, since when do you take all of your shots at the same range you are zeroed from?

It is hard for me to sit in my chair and question someone like you on that, but it definitely makes a difference.  Especially in closer or our further than your PBR.

And with 6" height over bore?  Vs 2.5"?? That doubles the distance of poa from poi.  No way that it doesn't matter.  Might not be as big a deal at the range you are zeroed, but for sure it will matter at different ranges.

And finally,  I have fired a lot from odd and awkward positions in my life.  I can tell you for a fact, if you have to shoot laying on your side, your POI changes drastically.

All I am trying to say is, height over bore matters, relative to the angle of the shot. For sure it mattere outside of your PBR and matters more as the amount if cant increases.
My experience shooting .177 cal HW springers (HW95 & Beeman rebadged R9) tuned to shoot at from 12.5 to 13.5fpe is that scope height above the bore does affect the point of impact at different ranges. When using "hold over aiming" with a 30 yard zero a scope close to the receiver the "trajectory flat spot" happens at closer ranges, however if the scope is higher above the receiver the  "trajectory flat spot" happens at the longer ranges. Here is an example of the "trajectory flat spot" (distance between the near and far zero) of a tune for my .177 R9 done a while back...........
(https://i.imgur.com/5ko3WLgh.jpg)
Notice that using a 30 yard zero and scope about 1 3/4" above the bore I had a "trajectory flat spot" of about 13 yards to 35 yards. This was when I was using a 3-12x40 Vortex Diamondback scope set in medium height mounts.

For a while now I've been using scopes with 50mm objectives so I've needed high mounts so the front bell would clear the receiver and have noticed that I have more issues hitting close targets on the FT course that I did when using medium mounts with 40mm front bell.
Title: Re: Optimal scope height study
Post by: Scotchmo on November 21, 2018, 08:55:17 PM

My experience shooting .177 cal HW springers (HW95 & Beeman rebadged R9) tuned to shoot at from 12.5 to 13.5fpe is that scope height above the bore does affect the point of impact at different ranges.
...
For a while now I've been using scopes with 50mm objectives so I've needed high mounts so the front bell would clear the receiver and have noticed that I have more issues hitting close targets on the FT course that I did when using medium mounts with 40mm front bell.

Ed,

No one is arguing that point. I think everyone knows that the difference between POI and drop varies depending on scope height. That would be a vertical dispersion.

A high scope will increase the amount of vertical error when you mis-range a close target. But that high scope won't increase the amount of error caused by a specific gun cant angle.

Bryan was arguing* about the scope height as related to cant angle. That is primarily a horizontal dispersion. I am arguing* that scope height has no bearing on gun cant angle.

* When I say arguing, it is in the good sense of what's needed for a productive resolution to any subject that is being debated.