GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => UK Airgun Gate => Topic started by: Elo76 on January 08, 2019, 12:28:26 PM
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Just thinking out loud here and looking for an explanation or comments.
I have a TX200 and HW97 that both shot low at 30. Both guns are fitted with a Hawke Sidwinder ED 10-50x60.
I'm guessing that since both of them are fixed barrel guns that I'm really not seeing droop.
Is this low POI a result of the large objective scope?
Also....I'm currently using Sportsmatch elevation adjustable mounts on both to compensate. My latest shooting session resulted in the mount moving on the TX. I'm thinking that maybe I should ditch the adjustable and try something else. Maybe a UTG drooper rail and a set of low rings? Suggestions?
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It really just depends on how much adjustment range your scope has, and how much you need to adjust. If it is off by 12 inches at 10 yards, there is an issue, and you will use up the majority of your scope's clicks. Find the mechanical zero of your scope and set it to center if you want to see how far you are moving the inside of the scope. If it can be adjusted and holds zero, you should be fine. If you are using 95% of the clicks and that bothers you or it won't hold zero, you will need to work something out. Any rifle can have issues that look like droop, as the mounts/grooves on the receiver can be misaligned as well, along with the alignment of the barrel. My .223 had nearly 20" at 100 yards, a bolt action, and my target scope wouldn't have had enough clicks. So work to the mounts or rings was necessary without buying a new scope with more adjustment range or adjustable rings/ or a 20 moa mount to point the scope downward. If your rifle just shoots a bit low, you are likely just fine. Custom milled rings are also available.
Vs
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What is the caliber of your TX 200? There will be more drop at thirty yards with a .22 than with a .177. What do you mean by low - an inch, a foot, a yard? Fixed non compensated rings should be fine on a fixed barrel rifle. You will need high rings so the objective clears the barrel. My TX 200 has zero droop and the point of impact at forty yards is only slightly lower than at twenty. It's a .177. I'm using a Hawke dovetail mount directly on the receiver.
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Look at the physics of the set up ....
If scope is optically centered your view threw it is parallel to the tube and mounts that will support it.
The barrel and receiver are parallel making the scope dove tails mount attaches too all on the same plane.
Whatever the scope height is ( Lets WAG @ 2 1/2" ) is the distance the pellets leaves muzzle LOWER than what scopes as viewed center line is.
* So is you looked threw scope at a dot on a target a few feet in front of muzzle and shot a pellet the POI would / should be the same @ 2 1/2" difference.
Now you have gravity pulling the pellet down and this value increases over distance.
YES shooting low is going to happen !!
Now if the UPWARD ELEVATION using turret correction is not able to compensate and raise POI at 30 yards ( Ideally being 1/4 or less of the total adjustment range turrets provide * If you have say 80 clicks either side of zero, then no more than 20+ to 20- ) then you need to go with adjustable mounts that in use are reverse of Droop actually creating a Muzzle higher than scope view condition.
Loose numbers presented, but to give you some idea on whats happening.
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When in doubt, shoot some targets at different ranges to get a fix on what the trajectory is doing relative to your scope line of sight. I use 5 yard increments from about 10 to 35 when checking a scope setting question.
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What is the caliber of your TX 200? There will be more drop at thirty yards with a .22 than with a .177. What do you mean by low - an inch, a foot, a yard? Fixed non compensated rings should be fine on a fixed barrel rifle. You will need high rings so the objective clears the barrel. My TX 200 has zero droop and the point of impact at forty yards is only slightly lower than at twenty. It's a .177. I'm using a Hawke dovetail mount directly on the receiver.
The TX is a .177 and it was 6" low at 30.
My HW97 is also a .177. I maxed out the elevation clicks to zero it at 30 so I went adjustable on this one.
Look at the physics of the set up ....
If scope is optically centered your view threw it is parallel to the tube and mounts that will support it.
The barrel and receiver are parallel making the scope dove tails mount attaches too all on the same plane.
Whatever the scope height is ( Lets WAG @ 2 1/2" ) is the distance the pellets leaves muzzle LOWER than what scopes as viewed center line is.
* So is you looked threw scope at a dot on a target a few feet in front of muzzle and shot a pellet the POI would / should be the same @ 2 1/2" difference.
Now you have gravity pulling the pellet down and this value increases over distance.
YES shooting low is going to happen !!
Now if the UPWARD ELEVATION using turret correction is not able to compensate and raise POI at 30 yards ( Ideally being 1/4 or less of the total adjustment range turrets provide * If you have say 80 clicks either side of zero, then no more than 20+ to 20- ) then you need to go with adjustable mounts that in use are reverse of Droop actually creating a Muzzle higher than scope view condition.
Loose numbers presented, but to give you some idea on whats happening.
Ahhhh....I don't know what gets in my head sometimes. I start with an optically centered scope and adjust my mount to get my elevation zero'd without using the turrets at 30yrds. For some reason I was thinking that if it was low...I had droop which is not the case. It's just laws of physics.