WestHunter Adjustable Scope Rings - Formula to calculate how much they adjust

[SkeeterHawk]

Hello everyone.

I wanted to "reach out" with my 2240, so I had to know how much adjustment I had on my turrets. This gun has a Hawke Vantage 4-16x50 scope that has an elevation turret range of 80MOA, or 320 clicks. My gun was zeroed at 50 yards, and it ended up being 239 clicks, or 59.75MOA adjustment, so I was almost out and needed to change over to adjustable rings. I got these from WestHunter. So now I am wondering how much to cant my scope to get it in range. Here is a link to a discussion on AccurateShooter forum and they discuss how to calculate it. My take-away from this is that there are four numbers that we are working with:
0.000291 = Constant
Distance Between Rings in Inches
Desired MOA Adjustment
Difference between rings in height

Formula:
Constant x Distance between Rings x Desired MOA adjustment = Difference between Rings in height

So, for example, if your rings are 4" apart, and you want a 20MOA adjustment, you do the following:
0.000291 x 4 x 20 = 0.023" in between the rings

My original rings had a shim in the back that was 0.019" thick. Reversing this formula we get:
0.019/(0.000291 x 4) = 16.32MOA, so my shim was giving me just over 16MOA of cant

So, I was adjusted up 59.75MOA on the turret, and had an additional 16.32MOA from the shim, so my scope was adjusted 76.07MOA to get zeroed at 50 yards.

Now, back to the WestHunter rings. They have six positions that they can be adjusted to, and this moves the ring up by 0.248", but there is 0.002" of "slop" in the adjustment, so I will use 0.250" because it is a nice round number.
0.250" / 6 positions = 0.04167" per adjustment

The calculation for each adjustment is:
0.04167 / (0.000291 x 4) = 35.7989MOA or (basically) 36MOA per adjustment

If I adjust it up two positions, it will give me 72MOA of adjustment, which means that when I adjust my turret all the way to the bottom, it will be zeroed somewhere just shy of 50 yards. I very frequently zero this gun in at 25 yards, so two positions will be too much for my usual shooting scenario, so I will only raise it one position. This ultimately means that my adjustment went from 16MOA to 36MOA, so I will have more than doubled my adjustment by going from the shim to the adjustable rings.

I have a few different versions of these adjustable rings, so I'll plan to put a caliper on them too, to see if the adjustment per position is basically the same, but they all operate the same, so I don't expect much of a difference.

I'm an engineering nerd, so this stuff is fascinating to me. I hope that it helps some of my airgunning brethren. Even if you just take my word for it, you now know that each adjustment of these adjustable rings gives you about 36MOA of adjustment when the rings are 4" apart.

Cheers!

Jonathan

 

[Pruitt58]

Amazing!

 

[SkeeterHawk]

Amazing!

Thanks @Pruitt58

To give an update, I went ahead and changed the back ring to be increased by two positions, which was was 0.0833" or 72MOA with the rings 4" apart.

Dong this, I was only able to zero the scope at just below 50 yards when the turret was at absolute zero. Since I was at the bottom of the adjustment, this seemed to affect windage also as when the turret was at the bottom, I only got about 10-15% of the adjustment available.

Here are a couple of pictures of the scope adjusted up two positions to give a cant of 0.083" with rings 4" apart.

 

[cavedweller]

@Sturkis = figured this was really good info

 

[Sturkis]

I use these rings and they work great

 

[airgunmike56]

I used flat feeler gages for checking plugs and points in cars on my mounts, Still drove me crazy had to sell them. ( The mounts not the gauges)
Mike

 

[SkeeterHawk]

This is my first set of West Hunter adjustable mounts, but I have had really good luck with the two other styles/brands of rings that I have purchased off of E-bay. This said, I'm thinking I may have broken my scope by cranking the elevation turret all the way down. The windage turret is really numb now, and the elevation doesn't have full range. I've been trying to contact Hawke since last Sunday with no response from them except an auto-response. I'll put another scope on this gun if I have to, to keep testing.

I'm not trying to hijack my own thread with a rant, but I am pretty disappointed that Hawke won't get back with me. I have multiple Hawke scopes.

 

[SkeeterHawk]

I have an update to this thread. Hawke got back to me this afternoon and pointed me to a procedure to get to the natural zero of the scope so that I can start from how they ship. I am in the middle of that procedure, so I have the optics completely disassembled again. I started looking carefully at how they were mounting, and noticed that the front ring especially would cant itself as I was torqueing it down. Removing the ring completely again showed that the WestHunter version of these adjustable rings have a set-screw on the bottom for the dovetail version...making it an even better ring for springers, BTW. Here are a few pictures of the screw sticking out of the bottom of the ring:

Here is where the set screw was marring the top of my breech

Daylight savings time screws me up royally, so it is dark already and I want to try to sight this gun again when it is daylight. I'll have another update within the next couple days, and hopefully I'll get this gun sighted back in finally...but with longer range this time.

Cheers!

 

[Mr.H]

Interesting post! All that math hurts my head. lol! Nice mod work, by the way.

 

[SkeeterHawk]

I finally have an update to this thread.

Following the procedure that Hawke sent me to get to the natural zero for the scope, along with setting up the set screw properly on the bottom of the WestHunter rings, I was able to re-zero the gun at 50 yards with the rings elevated by one "notch". Hawke recommended that I run the turret all the way up, and then go back down, rather than turning it down to zero and going back up. I now have 125 clicks to get to the top, where with the shim, I should have had 81 (I never counted it going up, so this is assuming that I have 320 total). 125-81 is 44 clicks that I gained, or 11MOA. According to the calculations, going from the shim to the adjustable ring should have yielded 20MOA, so I am 9MOA short. I think my rings may not be exactly 4" apart any more, coupled with the fact that we are talking about the thickness of a frog hair (0.001164") making an MOA difference and could be anything, the anodizing thickness, the thickness of the plastic ring insert, the depth or angle of the cut for the groove, etc. This is the reason why math is great to make sure that you are in the ballpark before you get started, but you don't "know" until you put it into practice in the real world.

I'd say that this is a winner. I now have 31.25MOA (125 clicks) of upper adjustment, which will definitely give me some more range with that gun. I also got to discuss the theoretical and real-world adjustments gained by adjustable rings, which has been educational for me to say the least. I hope you guys got something out of this too.

Happy and safe shooting...farther out now. Woo Hoo!

Jonathan

Nice mod work, by the way.

Thanks, Mr.H! She has been a work in progress...and is still going, and going, and going. I should paint the bottle to look like an Energizer battery!

 

[HubenK1Sniper92]

Way to much overthinking here, just adjust the damn rings to you hit the target and your done lol. I have a few set of those rings, by the time you dick around with your fancy math I already have mine adjusted, on target and went through 2 magazines

 

[MarksmanPete]

Thanks @Pruitt58

To give an update, I went ahead and changed the back ring to be increased by two positions, which was was 0.0833" or 72MOA with the rings 4" apart.

Dong this, I was only able to zero the scope at just below 50 yards when the turret was at absolute zero. Since I was at the bottom of the adjustment, this seemed to affect windage also as when the turret was at the bottom, I only got about 10-15% of the adjustment available.

Here are a couple of pictures of the scope adjusted up two positions to give a cant of 0.083" with rings 4" apart.
View attachment 312870View attachment 312871View attachment 312873

Woah are you bending the scope it looks like one is high and one is low.

 

[MarksmanPete]

Thanks @Pruitt58

To give an update, I went ahead and changed the back ring to be increased by two positions, which was was 0.0833" or 72MOA with the rings 4" apart.

Dong this, I was only able to zero the scope at just below 50 yards when the turret was at absolute zero. Since I was at the bottom of the adjustment, this seemed to affect windage also as when the turret was at the bottom, I only got about 10-15% of the adjustment available.

Here are a couple of pictures of the scope adjusted up two positions to give a cant of 0.083" with rings 4" apart.
View attachment 312870View attachment 312871View attachment 312873

I just bought these rings an am wondering if its safe for the scope wouldnt it bend it if I adjust an get like 30 moa? I got an arken epl4 6x24

 

[JP806TX]

Woah are you bending the scope it looks like one is high and one is low.

Yeah
I was never a fan of these 2 piece adjustable scope rings. It's too easy to bend your scope tube if you are not careful.

Save yourself some aggravation, spend some money and use a Sportsmatch one piece adjustable mount. $63?

Or if you want to save money and are handy, a bit of modification and this riser can be made adjustable in elevation and windage. Around $19.

https://www.amazon.com/dp/B076Y28TQZ/ref=sspa_dk_detail_0?ie=UTF8&psc=1&pd_rd_i=&pd_rd_i=B076Y28TQZp13NParams&s=sporting-goods&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM

 

[nervoustrig]

@Glem.Chally demonstrates in the following thread how they can be titled so as to not put stress on the scope tube.

Westhunter adjustable scope rings.

Pleasantly surprised, not even the 150$ sportsmatch can put them in a hard plastic case. Really high quality threads and anodizing, comes with shims to work with 1 inch or 30mm tubes. C$ 38.39 20%OFF | WESTHUNTER Adjustable Profile Scope Mounts 25.4mm/30mm Picatinny Riflescope Rings Adjust...

www.airgunnation.com

 

[JP806TX]

I've read that entire post 3 times.
All I see is

@Glem.Chally "Yeah if you take the screws out you can slide them sideways out (along the grooves) then drop them in the top where you want them. (Adding MOA) Then put screws back and tighten."

I don't see where he says how NOT to put stress on the scope tube. Because it looks like he's using a scope tube to align/angle both scope rings. Now if he was using a solid rod to tighten down and align both scope rings instead of a hollow tube (scope), then I could see how it might reduce stress on the scope tube.

@cosmic wrote " Me also a 34mm would be great.. I disassembled mine and using a flat file worked the grooves down some.. No problem with angling the rings now.."

That's exactly how I modified the riser above. Just file off the grooves on one side and then you can angle the rail up or down. The advantage is that it's once piece...No stress on the scope tube.

 

[nervoustrig]

My takeway from that thread is the clamping surfaces have serrations that discourage the saddles from tilting, but they do tilt by first removing the crossbolt.

In this picture they are clearly tilted:

If one were concerned about using the scope itself as a reference for locking in the setting, a piece of bar stock could be temporarily used. Based on how the saddle gets clamped between two plates, it looks like it would experience no torque/rotation when tightening the crossbolt so I don't think that would be necessary. But not having used them myself, I could be missing something.

 

[SkeeterHawk]

My takeway from that thread is the clamping surfaces have serrations that discourage the saddles from tilting, but they do tilt by first removing the crossbolt.

Yes, there is a little bit of "slop" in the tolerances of the slots so you can get them positioned before tightening the set screw down, and it will "auto-correct" the cant. That said, I don't feel comfortable adjusting it more than 2 slots front to back, and that was beyond the elevation adjustment of my scope at my given range. I doubt that they would be able to adjust as much as the picture that @nervoustrig just posted without damaging the scope...without major modifications to the rings themselves. You could go in there with a Dremel with a drum-sander and give relief for the rings if more than 2 steps were required, but that is not "normal"; however, I would feel good about doing that..

 

[MarksmanPete]

Yes, there is a little bit of "slop" in the tolerances of the slots so you can get them positioned before tightening the set screw down, and it will "auto-correct" the cant. That said, I don't feel comfortable adjusting it more than 2 slots front to back, and that was beyond the elevation adjustment of my scope at my given range. I doubt that they would be able to adjust as much as the picture that @nervoustrig just posted without damaging the scope...without major modifications to the rings themselves. You could go in there with a Dremel with a drum-sander and give relief for the rings if more than 2 steps were required, but that is not "normal"; however, I would feel good about doing that..

Okay so I think it should be good as I tested it on another scope I had and I just mounted it, I tightened down the scope rings before putting them on the pic rail, I didn't mount the rings to the rail first as your suppose to but that way when I put me scope I see one mount sits a little higher than the other one on the pic rail here is what I mean in the pic attached and the one in the back so it shouldnt bend the scope I think il go 2 or 3 or those tiny notches an that should give me plenty moa like 80 moa at least at at like 100 yards.

 

[Trucker3573]

I have them and while yes they are technically adjustable I don’t really see how they can be adjusted any other way than each ring at the same height or very close. IE you really can’t tilt the scope without damaging when you tighten it from what I see. This isn’t what I really think of with adj rings. Must say I’m not impressed personally.