MarauderAirRifle.com

[Supercharged86]

Hey Guys, There's still some discussions here and there about picking the correct ring height size based on the scope objective size; so I thought I'd help clarify and summarize things a bit. Overall, you want the lowest ring height possible while still providing adequate clearance. There's a few reasons for this which we'll save for another dicussion.

To get the lowest ring height possible you need just four measurements. If you don't have the scope in hand you'll need to get these from either the retailer or manufacturer. The first measurement is the scope tube outside diameter, this should be either 25.5mm (1" scope tube) or 30mm. The second is the objective end outside diameter. This will vary depending on manufacturer, for example my Centerpoint Adventure class 3-9x50mm scope has an objective lens OD of 62mm and my Leapers SWAT 6-24x56mm has a OD of 65mm. Next, you'll want to substract the two numbers and divide by 2,this will give you what I call scope tube offset. Next you'll want to measure the offset from the scope base to the shroud/barrel top; on the Mrod this is about 3mm (could be different for a .25), this is what I call the scope base offset. Simply subtract the scope base offset of 3mm or so from the scope tube offset and this number will represent the minumum ring height required to clear the shroud tube once installed. However, I've noticed that due to it's design, the 11mm dovetail rings when they are tightened down, don't generally sit flush on top of the scope base. There is usually a small space of about 1mm in between the two. Therefore, you can theoretically subtract an additional 1mm from the total number above, but for argument sake we won't, we'll use the additional 1mm as a buffer. The last number is the actual scope ring height and these also vary depending on manufacturer, not all mediums, etc. are the same height. You''ll need to check the specs from the specific manufacturer.

So as an example: My Leapers SWAT scope has a scope tube OD of 30mm and objective lens OD of 65, so 65-30=35, 35/2=17.5. Therefore, the scope tube offset is 17.5. Subtract the scope tube offset by the scope base offset of 3mm and you get; 17.5-3= 14.5mm. Therefore, the minumum ring height required to safely clear the shroud tube is 14.5mm. Hope this helps clarify any concerns people are having choosing ring height. Cheers. Steve

ps. If you prefer having the flip up lens cover installed at all times then measure the lens OD with the cover installed and use this number in the calculation above, otherwise it may not fit.

[Supercharged86]

Likewise, if your currently using high scope rings for example and would like to know if medium rings will fit then you need only three measurements. First measure the existing clearance from the objective lens to the top of the shroud. Second, measure the current scope ring height, this will likely include the 1mm that I mentioned earlier. Subtract the lens clearance from the overall scope ring height and this number will again represent the minumum safe ring height. So with my earlier example, the current installed ring height is 22mm (21mm scope ring + the additional 1mm) and my current lens to shroud clearance is 7.5mm; 22-7.5= 14.5mm. So again, 14.5mm represents the minumum ring height to ensure objective lens clearance. Cheers. Steve

[zen0s]

Hey Steve, just curious to why lowest mount is needed for the scope? Could you explain please? Thank you

[diarmadhim]

Really just for cheek weld, or chin weld if you use a really high mount...unless you are Jay Leno. You can install a kit to make your comb adjustable, but if you can use a low enough mount to get you a comfortable cheek weld you wont need it.
I have medium rings and they make the gun much more comfortable than the high rings I had on it.

[zen0s]

Ah I see hehe thank you kindly

[Supercharged86]

The other main reason for using the lowest ring height possible is to keep the optic and rifle bore center lines as close together as possible. By reducing the angle difference between these two imaginary lines, you reduce the amount of elevation adjustments needed throughout your potential shooting range. Some might argue that given the limited range of the Mrod, (100 or so yards for plinking, less for effective hunting), worrying about a few degrees of angle would be overkill. Well perhaps, but for me, accuracy is everything. So If I can eliminate the need for excessive turret adjustments or less holdover/under, then that's what I'll strive for. cheers. Steve