Air Arms S510

rcs9250

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Jan 20, 2019
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I recently received an Air Arms S510. 

The rifle has an 11mm dovetail scope mount. 

I bought a pair of UTG Pro scope rings, the ones that list for $59. Like most dovetail rings, the description says 11mm and 3/8”. 

11mm converts to .433” and of course 3/8 is .375”. 

Without making a simulated 11mm dovetail rail that I can mount the rings on and check if the scope is truly on center of the 11mm, does anyone know if it should be ? 

I’m under the assumption that a 3/8” dovetail with an 11mm / 3/8” scope ring, the scope ring would be shifted off center by .029” .

I realize it’s not a lot but if you sight in at 15 yards and then shoot at 50 or so yards or any distance, there would always be a required windage adjustment because of the offset condition. Am I right on this?

Randy


 
An 11mm rail is dimensioned to the widest part of the dovetail whereas a 3/8" rail is dimensioned to the narrowest part…which is how 3/8" (0.375") is paradoxically larger than 11mm (0.433"). A 3/8” dovetail will usually measure 12mm - 13mm across the widest part.

Most rings have reversible plates made to accommodate both 11mm and 3/8" rails. The tooth on one side has a 45° angle. The other side is a shallower angle…that one is 60°. The 45° is for a 3/8” rail. The 60° is for an 11mm rail.

Also, there is absolutely no necessity that the rings perfectly center over the receiver provided you orient the reticle to the bore and hold the reticle level when shooting. However, do take care to avoid accidentally having one ring at 45° and one at 60° because that will cause your scope to diverge from the bore line.

See here for how to avoid both sources of cant, scope cant and gun cant:
https://www.airgunnation.com/topic/scope-reticle/
 
jwrabbit123, the rings are part number RDU013022 They’re actually pretty nice rings .

I’ve seen the Millet rings before. The thing that I’m not keen on is when you clamp down it’s very possible you won’t be coaxial and causes the scope to bend at the turret junction. 

MMCMM13, I think I’m going to order a set of BKL’s. Thanks.

nervoustrig, I was not aware of where those dimensions were referenced from. I will do a search and try to find a drawing. 

In the second part you mention orienting the reticle to the bore centerline. Not sure how to accomplish that other than mount it and shoot at 25 yards, then shot at 50 yards and see if windage is still at the same zero. I’ll try it but maybe I’m trying to split hairs. I had a rifle (.22lr) that I bought an Athlon for it. When going from 25 to 50 yards I had to add a windage correction in addition to an elevation. And it was a no wind day. 

Thanks all,

Randy


 
In the second part you mention orienting the reticle to the bore centerline. Not sure how to accomplish that other than mount it and shoot at 25 yards, then shot at 50 yards and see if windage is still at the same zero.

Yes, the trial and error approach can work but it can be tedious, and you have to be very careful not to introduce gun cant. A quick and foolproof approach is with a laser bore sighter but it can also be done with nothing more than a mirror.

Set up a mirror at a distance of, say, 5 yards and set your AO to 10 yards. Look through the scope at your reflection in the mirror. Twist the scope in the mounts until the vertical bar of the reticle simultaneously bisects both the muzzle and objective bell. Then lock it down. If it's hard to see your muzzle, add a little dot of White Out or take a dot from a hole punch and tape it to the muzzle with clear tape.

See here for a more thorough description of scope mounting and preventing cant error:
https://www.airgunnation.com/topic/best-way-to-level-a-scope-2/#post-1003404