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AO weakness

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 13:48
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 There is an ongoing discussion in a smokeless muzzleloader forum concerning the failure of rifle scopes mounted on very hard kicking rifles.  These modern muzzleloaders are kicking out 300 grain projectiles under as much as 80 grains of powder at 2400+ fps from the muzzle.  Great scopes like Zeiss Conquest, Bushnell 4200 and Sightron Big Sky are breaking at an alarming rate and many times it is the parallax adjustment that goes whether it is on the objective bell or side focus. 
 
 I have never seen this particular subject arise on this forum and was wondering if others have noticed the AO feature of a scope to be a mechanical weak link in rifle scopes atop hard kicking hunting rifles?
 
One offered solution was to go with Nightforce scopes since they have proven themselves to be solid as tanks.  The drawback is that most of them are very heavy.  Nightforce evidently has two new scopes out that are lighter in weight which is the 1-4x24 with FC-2 reticle and 2.5-10x24 with NP-1 or Mil Dot.  Any input on either of these non-AO scopes as a reliable scope for hard recoiling hunting rifles?
 
 Doug


Edited by dougedwards - December/28/2008 at 20:57
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 14:24
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entirely ignorant on blackpowder, please forgive, why do you need ao on a black powder gun???

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 14:29
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Great reply Dale.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 15:29
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 I don't even think it is possible to shoot a 250 or 300 grain bullet to 2400+ fps with black powder.  If it is it would require LOTS of powder and a very long barrel.    I am using Reloder7 and 10x as my powders of choice but there are many other from with to choose.  You have to understand that these rifles are capable of MOA accuracy out to 400 yards and beyond.
 
Is there no opinion on the AO features of scopes as it pertains to my question??
 
 Doug
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 18:44
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Yes I know some folks in the price area of utah who shoot at steel cut outs of buffalo with crossed sticks, 8 inch long venier peeps, 45,something or other black powder cast bullets, paper patch, at 1000 yds. they don't cook their meat and none of the alcohol is filtered, but what the hell. (some have a wife for each gun) sorry back to the subject.

not saying they aren't sub moa guns but with a 45 cal bullet, its larger than the error from the parallex caused by the ao error. how do they know which one causes the error? also the ao advantage is dependant on zoom range, unless its a fixed power of course, but never saw one on anything less than 12x. this type of recoil is seen routinely in three gun matches with 3 inch slugs and semis. but the shots are only to 100 yds.

I seriously doubt if these guns recoil as much as my 416, but I could run some calculation, I just use leo v3 low range variables.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 19:15
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Originally posted by Dale Clifford Dale Clifford wrote:

Yes I know some folks in the price area of utah who shoot at steel cut outs of buffalo with crossed sticks, 8 inch long venier peeps, 45,something or other black powder cast bullets, paper patch, at 1000 yds. they don't cook their meat and none of the alcohol is filtered, but what the hell. (some have a wife for each gun) sorry back to the subject.

not saying they aren't sub moa guns but with a 45 cal bullet, its larger than the error from the parallex caused by the ao error. how do they know which one causes the error? also the ao advantage is dependant on zoom range, unless its a fixed power of course, but never saw one on anything less than 12x. this type of recoil is seen routinely in three gun matches with 3 inch slugs and semis. but the shots are only to 100 yds.

I seriously doubt if these guns recoil as much as my 416, but I could run some calculation, I just use leo v3 low range variables.

 
 Thanks for the reply.  I am wondering if you have a scope with AO on your 416.  Or if anyone who has the AO feature on a scope of any really hard kicking rifle has experienced the adjustment getting stuck and not being able to adjust it at all.  This isn't about the small amount of parallax error encountered when shooting at varying distances.  What is happening is that the scope is not able to focus throurgh out the whole magnification range.  I actually own a Kahles CL Multizero 3-9x42 which just happens to come with a side parallax adjustment.  I agree that AO isn't particularly needed for this magnification but I had to send the scope back to Austria when the adjustment got stuck for repair.  It was stuck on 30 yards and would not focus on any magnification over 6x.
 
 Maybe it is all just coincidence that so many smokeless muzzleloader shooters have high failure experience with scopes in general but I don't think so.   Actually the AO is only one of the mechanical failures experienced by Zeiss, Bushnell, Sightron, Leupold, Nikon and many other manufacturers of rifle scopes but a good percentage of the mechanical failure seems to manfest itself as a stuck AO adjustment.  If noone here has experienced this phenomenon then possibly it is just coincidence.  I am trying to determine that.
 
 Doug
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 19:27
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Correction these are inline smokeless rifles not muzzle loaders...a real muzzle loader does not wear a scope. and they are not shot beyond 150/200yrds.. not trying to be rude or offensive just letting people know the difference. and 2400fps thats smokin!  no pun.....
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 20:04
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Originally posted by rifle looney rifle looney wrote:

Correction these are inline smokeless rifles not muzzle loaders...a real muzzle loader does not wear a scope. and they are not shot beyond 150/200yrds.. not trying to be rude or offensive just letting people know the difference. and 2400fps thats smokin!  no pun.....
 
 Yes I hear alot of that and I somewhat agree with you.  The only thing that makes these rifles muzzleloaders is that you must load from the muzzle and the powder is not encased.  This is why I would like to get the focus off of the fact that these scopes are failing on "muzzleloaders" unless for reasons that I cannot think of.......these smokeless rifles are reacting in some different manner than centerfires as far as recoil is concerned.
 
 Also I have read lots of posts on this forum stating that nothing over 10x is ever required for whitetail deer hunting.  While this might be true there is nothing wrong with being over magnified if it isn't costing in other areas.  Many have chosen scopes that are also utilized as spotting scoes at the range or for scrutinizing the antlers of feeding deer at long range.
 
The consensus in the smokeless muzzleloader forum is to stay away from scopes that have the AO feature as they seem most suseptible to mechanical failure.  I am just trying to determine if the AO feature is truly a weak link in the mechanical make-up of a rifle scope.
 
 Doug
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 20:14
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I only have one AO and its on a little 22/250 so no answer from me but I have never heard of this happening before,doesn't mean it hasn't but I also have never seen one on a inline either. but you are obviously having issues.I would contact one of the scope companies first hand. best of luck!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 20:28
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Parallax adjustment brings in more moving parts.  Perhaps there is something about the recoil impulse of these rifles that wreaks havoc on modern scope, but I have not heard that before.

Perhaps the solution is to try a fixed power of some sort (like Super Sniper 10x42) or IOR 6x42.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 22:01
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ive had all kinds of scopes failures, the worst guns on scopes are large caliber handguns, 454, 500 sw , large caliber T/Cs .. is there a specific group of zoom range that is failing. also a 300+80 gr at 2400 fps is right in the 416 recoil range, are these guys bench these guns on lead sleds or something-- a little more insight into the conditions would help.
as to your question off a common link of ao failing -- I don't recall the topic coming up as long as I've posted on the forum.  


Edited by Dale Clifford - December/28/2008 at 22:02
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/28/2008 at 22:03
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Originally posted by dougedwards dougedwards wrote:

 
One offered solution was to go with Nightforce scopes since they have proven themselves to be solid as tanks.  The drawback is that most of them are very heavy.  Nightforce evidently has two new scopes out that are lighter in weight which is the 1-4x24 with FC-2 reticle and 2.5-10x24 with NP-1 or Mil Dot.  Any input on either of these non-AO scopes as a reliable scope for hard recoiling hunting rifles?
 
 Doug


Either one of the Nightforce scopes you list have been out for a number of years and are very reliable. I would not hesitate to use one on any hard recoiling rifle. Also there are more reticle choices available than the ones you list. I like the 2.5-10 with the NPR2 reticle.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 12:02
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Originally posted by Dale Clifford Dale Clifford wrote:

ive had all kinds of scopes failures, the worst guns on scopes are large caliber handguns, 454, 500 sw , large caliber T/Cs .. is there a specific group of zoom range that is failing. also a 300+80 gr at 2400 fps is right in the 416 recoil range, are these guys bench these guns on lead sleds or something-- a little more insight into the conditions would help.
as to your question off a common link of ao failing -- I don't recall the topic coming up as long as I've posted on the forum.  
 
 There doesn't seem to be a specific group of zoom range that is being affected as it ranges from 3-12 to 5-24 and everything in between.  We do sometimes use Led Sleds at the range.  I know that I do.  One thing I have noticed is that almost all of the failing scopes sported a 1" tube but none that I know of had 30mm or more main tube.  You would think that recoil would have a similar affect on both scopes no matter the main tube size because they have similar internals.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 12:07
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Originally posted by Sparky Sparky wrote:


Either one of the Nightforce scopes you list have been out for a number of years and are very reliable. I would not hesitate to use one on any hard recoiling rifle. Also there are more reticle choices available than the ones you list. I like the 2.5-10 with the NPR2 reticle.
 
 The Nightforce and IOR Valdada scopes do seem to built like tanks and are very reliable.  They have two drawbacks.  One is the price.  The other is the weight.  But if I want to be sure that my scope is aligned and sighted in when a nice buck walks out I guess I am going to have to sacrifice in some areas.
 
 Doug
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 15:20
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Originally posted by dougedwards dougedwards wrote:

One thing I have noticed is that almost all of the failing scopes sported a 1" tube but none that I know of had 30mm or more main tube.  You would think that recoil would have a similar affect on both scopes no matter the main tube size because they have similar internals.

In general, the 30mm tubes are going to flex much less during recoil which will only help in keeping the internal bits rigidly mounted and aligned properly.  A wet noodle is a difficult place to put a complex optical system with moving parts and expect it to last, no matter how good the internals.

Of course tube size doesn’t directly affect the strength of the actual adjustable objectives, that’ll come down to the size/weight of the glass itself vs. the strength of the adjustment mechanism.  Though one might expect many of the cheaper/lighter weight 1” scopes to have less beefy construction in that area.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 16:19
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Originally posted by Jon A Jon A wrote:

Originally posted by dougedwards dougedwards wrote:

One thing I have noticed is that almost all of the failing scopes sported a 1" tube but none that I know of had 30mm or more main tube.  You would think that recoil would have a similar affect on both scopes no matter the main tube size because they have similar internals.

In general, the 30mm tubes are going to flex much less during recoil which will only help in keeping the internal bits rigidly mounted and aligned properly.  A wet noodle is a difficult place to put a complex optical system with moving parts and expect it to last, no matter how good the internals.

Of course tube size doesn’t directly affect the strength of the actual adjustable objectives, that’ll come down to the size/weight of the glass itself vs. the strength of the adjustment mechanism.  Though one might expect many of the cheaper/lighter weight 1” scopes to have less beefy construction in that area. 

 
 
I've always been a firm believer in light scopes.  THe lighter the scope the less affect recoil inertia forces have on the optics.  So while a 30mm scope is typically stronger it is also typically heavier.  How much each affects durability will vary by brands and models obviously.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 19:28
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That's where that strength/stiffness to weight ratio silly concept comes in.
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Originally posted by Jon A Jon A wrote:

That's where that strength/stiffness to weight ratio silly concept comes in.
 
What's so silly about it?  Someone should do an independent torture test.  I think Pyro said he'd volunteer some scopes.
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THe lighter the scope the less affect recoil inertia forces have on the optics.
you lost me on that -- could you show me the physics?
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Originally posted by Dale Clifford Dale Clifford wrote:

THe lighter the scope the less affect recoil inertia forces have on the optics.
you lost me on that -- could you show me the physics?
 
Imagine as the gun recoils...you have a scope bolted to the gun.  So the gun is sharply recoiling backwards and we are expecting the scope to come with it.  The lighter the scope the easier it will go from motionless to.....violent recoil backwards.   Simply put, a lighter scope will move more freely with the recoil of the rifle.  It will resist a sudden change in direction less than a heavy scope.  Someone wrote...an object at rest will stay at rest....
 
The real question is....how big of a difference does it make?  What's the "silly ratio"? 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 21:05
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It is odd that since black powder is a slow burning powder and does not have the sudden impulse of High Power powders that it would create problems. A black powder is more of a push than than the slam of a magnum rifle. If there is a problem it must come from the fact that the recoil period is much longer in a black powder. The energy impulse is less in intensity yet longer in duration. This would push the tensile stress limits more in a light scope than in a heaver scope. You need to improve your data base with more specific numbers of failures, model and brands of scopes incurring problems. List of the exact type and point of faliure. Without this it will be imposable to produce a motion mechanics model to replicate the inferred failures. If there are many types of failures it would tend give more the impression that this could be the debate of an internet hoax.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/29/2008 at 21:09
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I'm sleeping at a Holiday Inn Express tonight.  I'll report back in the morning.  This &*^ makes my headspin.Whacko

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Originally posted by Horsemany Horsemany wrote:

What's the "silly ratio"? 

Nearly double the stiffness (~75% increase, depending upon exact wall thickness) for less than a 20% increase in weight.
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Originally posted by Jon A Jon A wrote:

Originally posted by Horsemany Horsemany wrote:

What's the "silly ratio"? 

Nearly double the stiffness (~75% increase, depending upon exact wall thickness) for less than a 20% increase in weight.
 
I'm not doubting but how do you know that?  And how many 1" scopes are deficient in tube strength(aside from 2 piece tubes like VX II's)?  Until I have a 1" scope fail me or anyone I know I'll likely keep using them because I don't like adding bulk to light rifles.  However most of my bench guns use 30mm scopes.
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the stiffness ration is a geometric proportion between the secants of two circles one having a larger radius , and as the same angle is used the area of subtension is larger and stronger.

for every action there is an etc..     the recoil and recoil velocity of the combined wt. of the gun and scope will always be higher in the lighter combination. the higher inertial mass of the heavy scope will give a lower recoil  and recoil velocity thus "protecting" the  heavier scope more.
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