How to check your scope rails…
So….
The trirail from AF is about 1/64″ off center and the single piece mount for my scope from accushot was about 1/32″ off center, add these up and suddenly the scope is far left of the centerline of the rifle…
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Who the hell designs these things and do they know ANYTHING about how it works?!?!!?!?!? WTF!!!!!
Fine if your only shooting at 35 yards any thing closer will hit to the left of the centerline of the crosshairs any thing further it will hit to the right.
Goto shoot a FT setup at various distances and everything is fucked no matter where you setup the scope…
SO I made a funky little gauge from a leftover part for the silent pellet trap. I bought a breaker panel for the outside box, it was cheaper then the outdoor ones. And it had a little spot inside (that I removed) for the wires to attach to the panel.
Well each hole is threaded for screws to retain the wire and with a few longer screws I was able to make a gauge to check the center the scope on the frame of the rifle.
Mine was about 0.03″ too far to the left off center, I used the gauge to determine how far it was off from one side and divided it by two and reused the gauge to check alignment after shimming. I used a thin piece of pvc sheet to shim, should work well…
Here are a few photos.
First one shows the part with screws to check alignment.
The second shot shows the shim…
HH
JW
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Which level is that?
That’s pretty slick and you can see it from the shooting position…
Killer groups… 😯
Jim, I hear you. Some gun may have this problem and some may not, you came up with a great fix for it that will help us find it. I have mine zeroed at 30 yards and I shot the top target at 15 yards and the bottom at 12yards the lowest my scope will go and things are still pretty lined up. Some of the levels that I used are in the last pic. and I did use a plum line that I did not mention in my post above.
I keep this one on the Condor to help me from canting the scope. Note it on the back of the gun’s rail. zero cant of the scope will help alot.
If your levels are not exactly perpendicular or parallel to the rails you will see an incorrect bubble location.
Check it out, slightly rotate the levels say 1/64 of an inch (at the end) and the bubble will move accordingly…
I have a few that I rubber band to the rifle but I keep them snug against the scope mounts to keep it as perpendicular to the rifle as possible…
I didn’t think it was an issue but when I shoot at 15 yards and then switch to 35 or 40 I notice a difference that is several pellets widths or almost a full rotation of the windage knob off …
When I mounted the scope I had go to max right windage adjustment just to get it to hit the target, I think the effect is far greater than one may think…
I might as well mount the scope on the bench and screw the gun to the bench as well because it is so far off that it is only good at one distance…
To make an analogy it is just like mounting really high mounts and trying to dial in for different distances, the greater the height the more adjustment to be accurate… But realize you now adjusting windage not elevation… Without adjustment you have to double correct to hit the target… The scope is only good to see where you hit at that point.
Flipping the mounts would correct the issue if the mounts were exactly as off as the tri-rail…
Considering THE only use for a scope if for it to be aligned with the barrel I find it very alarming that the scope mounts and the rails are so off that some cardboard and hot glue could make a better mount…
Its like producing a valve that doesn’t work at typical operating pressure, or like making a rifle that doesn’t fire…
It is NOT hard to get it right…
WTF!
I’m with Ninja on this. I installed bubble levels (I have 3 from other gun’s that monut on the rails) on my Condor rails, The tri-rail, The top rail on the Condor and on the front rail by my laser and one on the scope. And yeah things are not straight, but I think I have it close and it’s shooting that way. the rail by the laser closets to the barrel is way off if you look at all the other levels but, I set that one (by the barrel) as the standard denviation and adjusted the scope to it. it worked out pretty good. One would need 3 or 4 levels to get the barrel right with the scope and that is the main gaol. I was able to remount the tri-rail to get things so close that it’s OK. If your shooting at very small targets like 1/4 for FT, yeah it maybe a problem and my gun will stay with in a 1/2 target CTC at 30 yards. That should be great for hunting?
Just turn mount facing the other way?
If you scope is off the centerline 1/32 (0.03125″)
Then if the gun is zeroed at 25 yards, the most the pellet will be off due to this problem at zero and 50 yards will be .03125″.
Air Force can only WISH their guns were accurate enough for that to matter.
Not that I’m saying this is not an issue, but it doesnt matter enough to me for me to worry about it.
Why not extend the rig a bit farther and actually check the scope tube? Who’s to say that your scope rings arent offset to one side or the other?
Synopsis that is a frigging awsome discovery!!! great jig you made up to check it out too!
For Field Target no variance is acceptable…even being off 1/4″ at 40 or 50 yards can easily cause a miss… to minimize any variance you would have to zero at 50 yards NOT 10 yards which would throw your shots way off come 50 yards.
Going to definitely have to add this to the notebook! Jim.
thanks man, now i understand ! 🙂 every day is a schoolday 8)
Vincent.
If you scope is off to one side of the centerline, then to make the pellet hit perfect zero at lets say 30 yards, then the centerline of the barrel and the reticle must intersect. Which means they must cross, they cross at the point where the rifle is zeroed and at that point it changes from left to right, or right to left.
Just the same as if you laid your gun on its side.
Obviously if your gun is only 0.005 inches off the centerline to the left thats the most it will ever be off at distances less than the distance the gun was zeroed at. At distances above the zero range, then the offset will be on the other side and will increase with distance beyond 0.005 at double the zero distance.
I have a problem with it from a QC standpoint, but I wouldnt sweat it on the guns accuracy. Distances were talking about are kinda small and almost negligable.
i’ll hope you guys forgive me my ignrance, but i don’t understand how at 30 yards you would have a p.o.i. on the left, and then further downrange a p.o.i. on the rigth. i do see how the gauge works, but would like to know how p.o.i. goes from either left to right or the other way around when the scope isn’t center.
Nice job!
Had no idea this could happen!
Would adustable rings fix it?
Thanks for the heads up Jim.
Great work JW…
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That’s pretty slick and you can see it from the shooting position…
Killer groups… 😯
It’s at B-Square Scope Level and the one on the Condor will have to stay so I need to order one more.