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WOULD A WHITE SCOPE ?????? |
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melloroadman
Optics GrassHopper Joined: July/26/2009 Status: Offline Points: 13 |
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Posted: July/26/2009 at 19:18 |
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I am having vertical poi shift as the temperature goes up and it is elevated when the scope is in the direct sun light . I have removed the scope and used the rifles with iron sights and it has improved the problem greatly . If I wrapped the scopes with white tape do you think it would help .Marvin
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safariarms man
Optics Apprentice Dolphin Overton Joined: June/28/2009 Location: K67BB Status: Offline Points: 111 |
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More info, such as the brand of rifle, caliber, ammo type, stock, scope, mounts and bases, temperature changes, distance shooting, amount of change in the poi, shooting set up, etc would help. Using irons may just mean that your groups are so large that you cannot tell if you are having vertical poi problems. Let us know.
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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1. What scope (make and model)?
2. What mounts? 3. What rifle? 4. What ammo? 5. What distance? 6. Do you see similar issues with other scoped rifles? 7. At what temperature range are you seeing the problem? 8. Do you only see the problem after the rifle/scope get hot? 9. What is your level of experience/comfort in marksmanship? 10. Have you tried cooling the rifle/scope, then shooting again? Depending on the setup and the ambient temp, it is possible, but not probable. Are you going from 65 degree house to 130 degree Death Valley range? if not, I kinda doubt that is the issue. But we should be able to help find the issue. |
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Freedom is something you take.
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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"Great minds...", or something. |
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Freedom is something you take.
Respect is something you earn. Equality is something you whine about not being given. |
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melloroadman
Optics GrassHopper Joined: July/26/2009 Status: Offline Points: 13 |
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3 different .177 air rifles . Groups are 10 shot strings 1- 11/2 inches 65 yards with irons or scope . Scopes are 3 bsa 3 x 9 air rifle rated and one bsa contender . Temperature can change from 68 degrees at 8 a.m . to 90 -95 by 10;30 am . Mounts are two piece bsa . The elevation shift is as much as 3 - 4 inches in direct sun with scopes and with iron or target apertures it is only 1 -2 inches . All 3 Scopes showed the same lift pattern . Marvin |
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amk204
Optics Apprentice Joined: December/27/2007 Status: Offline Points: 75 |
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sounds like its more of a gun prob. than a scope prob. poi changes with or with out scope, diff. in hight is close to the diff. of your line of sight.
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Life is to short to shoot an ugly gun
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safariarms man
Optics Apprentice Dolphin Overton Joined: June/28/2009 Location: K67BB Status: Offline Points: 111 |
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Maybe with just both have ESPN.
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safariarms man
Optics Apprentice Dolphin Overton Joined: June/28/2009 Location: K67BB Status: Offline Points: 111 |
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3 different rifles and 3 different scopes and I assume all are mounted with the 3 different scopes with each having their own set of mounts. Odd, no common denominator, except the brand of scope and rings, but that would be unusual for the same problem to occur on the different rifles. Are the rifles all the same brand and model or different makes? Have you tried different scopes on different rifles? What type of .177 pellets are you shooting? All lead, or some of the fancier copper stuff? Just out of curiosity, try shooting to a point of aim that you would normally do at 830, but do it at 1030, without ever shooting the rifle before that time and make sure the rifle is at the same temperature it would be at 830.
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Welcome to OT, Marvin!
Just out of curiosity, how did you gather the data to isolate temperature as the lone variable that you suspect is causing this problem? Not implying that this isn't precisely what's causing the problem; I've just never heard of this before, and I frequently shoot in the heat, living in Texas. I even shoot prairie dogs on the open plains of NM and the TX panhandle, with the rifle sitting out in the hot sun all day long, and I've never seen this cause POI shift.
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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hunterwingler
Optics Master Joined: April/03/2009 Location: Idaho Status: Offline Points: 1420 |
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what brand of air rifles are they. sometime the scopes that come with
they airguns sucks, then again u did say they was bsa scope that could
be it right there.
Edited by hunterwingler - July/27/2009 at 19:06 |
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I wasn't upset about the black cat crossing my path this morning but mouthing "your fu@#ed" as he passed was just rude.
If Guns kill people mine are all defective |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Ah, yes; I missed that part. My admittedly brief experiences with BSA scopes have not been very encouraging, to put it mildly. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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melloroadman
Optics GrassHopper Joined: July/26/2009 Status: Offline Points: 13 |
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I have paid very close attention to wind , temp , target shadow , sun angle , the last 4 times out too the range . And the scope might not be as big of a problem as I thought . I have been using my .177 condor with target aperatures front and rear these past 4 times . I am using crosman 10.5 grain pellets at 1000 fps at 65 yards . I think I am at the max that that pellet will go as far as fps and distance which is not helping . I will soon be making my own pellets and will be able to up the grains to 32 if I want . I am shooting at a range that faces more west than north and this is causing some problems . The light pellet is being effected buy the heat more than the scope . Two days I had really no temp. change and the poi stayed OK as far as height goes . But today the temp went up and as it did the poi did as well . This is with me and the rifle in the shade but the target in the sun 65 yards away . It was calm enough I could see what was going on this time . Then the wind picked up to 5 -10 mph and I had to compensate for that . Marvin
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Urimaginaryfrnd
MODERATOR Resident Redneck Joined: June/20/2005 Location: Iowa Status: Offline Points: 14964 |
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"Always do the right thing, just because it is the right thing to do". Bobby Paul Doherty Texas Ranger |
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hunterwingler
Optics Master Joined: April/03/2009 Location: Idaho Status: Offline Points: 1420 |
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i could be wrong but i dont think the heat or cold really has anything to do with how a pellets flys.
Edited by hunterwingler - July/28/2009 at 01:20 |
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I wasn't upset about the black cat crossing my path this morning but mouthing "your fu@#ed" as he passed was just rude.
If Guns kill people mine are all defective |
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safariarms man
Optics Apprentice Dolphin Overton Joined: June/28/2009 Location: K67BB Status: Offline Points: 111 |
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Sounds like as you expect. As the temperature rises, hot air rises and the low mass projectile at a relatively low velocity rises a small amount resulting in only a change in your vertical poi upwards. This would make sense given the multiple variables and no real common denominator except for the change in temperature and the fact that the change in poi is only in the vertical dimension and upwards. It will be interesting to see how your higher mass pellets work given their inherent higher momentum. Let us know how they react to the temperature changes.
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melloroadman
Optics GrassHopper Joined: July/26/2009 Status: Offline Points: 13 |
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I will but it might be awhile . I ordered a Corbin die 9 months ago and was told it would be 6 - 12 months for delivery . Hopefully I am 3/4 of the ways through the wait . Marvin
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amk204
Optics Apprentice Joined: December/27/2007 Status: Offline Points: 75 |
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try this, zero the scope in the 85-95 deg. heat. then shoot it the next a.m. to check poi. it should be 3-4 low. this is because your velocity is standerd ( lower ) in the am, and high ( higher ) as the temp goes up. hot air expands faster than cool air thus causing higher fps.
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Life is to short to shoot an ugly gun
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melloroadman
Optics GrassHopper Joined: July/26/2009 Status: Offline Points: 13 |
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Yes that is what has happened . What was throwing me off for a while was as the sun goes higher the shot goes lower and some days this was balancing out and some days not . Those are good hours for me to shoot and be comfortable . But it puts me at the worse time of day as far as the sun and the horizon movement as well as target shadows .Thanks Marvin
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