Rifle Scopes How does Leupold measure their STD base and rings?

[J!m]

(Disclaimer: I did search first!)

Hey guys. I'm putting together a 30mm base for my M40A-1 rifle, and have some questions...

I have an email in to Leupold but I'm turning blue holding my breath waiting for them to reply.

I have the dimensions of the scope, and the published dimensions of their rings, but not a clear understanding of how they measure the rings.

The Mark 4 10X scope has a 2" OD on the objective end. Therefore CL is at 1"

It has a 30mm tube (1.181") so the CL is at .590"; leaving .410" below the tube to the bottom of the objective bell.

"low" 30mm rings are .650"
"med" are .770
"high" are .900
"super high" are 1.000

The barrel is 1.2" so essentially even with the receiver. This tells me I need to have 1" from scope centerline to mounting surface of the base. (as a minimum)

I doubt very much the "super high" rings are the correct choice, and therefore I'm also assuming that number is from centerline of the ring to the TOP of the base. But, I have no idea.

Assuming this is true, I need the thickness/height of the 700SA base.

Now, just to keep things interesting, Leupold also offers a 20MOA base! So you have the vintage look (after welding!) and gain 20 minutes with the base. VERY cool. Since this scope is not "correct" and neither will the mount be (but sort-of have the look), I think this is a good option. So, how much do I loose with 20 minutes of angle? I'm guestimating 0.030" at the objective bell...

I'd like to keep it 'tight' to the barrel, even if I can't put a flip-up cap on there. But I guess a cap and/or sunshade would be useful.

For those who have mounted more scopes than I have... Thanks for the guidance!

 

[Danep21]

Leupold measures their ring height, from the top of the base, to the center of the ring.

 

[spife7980]

Its from the centerline of the ring to the top of the base. So with the standard rings you would take that height for the ring and have to add it to the height of the base.

Standard rings [IMG2=JSON]{"data-align":"none","data-size":"full","height":"319","width":"425","src":"https:\/\/media.midwayusa.com\/productimages\/880x660\/Primary\/566\/566805.jpg"}[/IMG2]


Standard base- note that these are not compatible with the canted base you discussed. This base goes in place of the canted rail. [IMG2=JSON]{"data-align":"none","data-size":"full","height":"335","width":"446","src":"https:\/\/media.midwayusa.com\/productimages\/880x660\/Primary\/227\/227012.jpg"}[/IMG2]


Here are the standard fit together and they go directly on the rifle like the rear displays. [IMG2=JSON]{"data-align":"none","data-size":"full","height":"447","width":"596","src":"https:\/\/media.midwayusa.com\/productimages\/2200x1650\/Primary\/245\/245357.jpg"}[/IMG2]





The canted rail is a picatinny rail- picatinny being the cross slotted design, weaver is a similar design but the dimensions are different. Picatinny has a wider channel than the weaver so weaver rings will fit on a picatinny rail but picatinny rings wont fit in a weaver rail. [IMG2=JSON]{"data-align":"none","data-size":"full","height":"369","width":"492","src":"https:\/\/media.midwayusa.com\/productimages\/2200x1650\/Primary\/809\/879882.jpg"}[/IMG2]


For the picatinny rail you would want a picatinny ring [IMG2=JSON]{"data-align":"none","data-size":"full","height":"384","width":"512","src":"https:\/\/media.midwayusa.com\/productimages\/880x660\/Primary\/635\/635361.jpg"}[/IMG2]

 

[Danep21]

^^ Correct. However, Leupold does make a 'Long Range' STD base, which has a 20 MOA Cant, Part #51734 that will fit STD Rings.

 

[spife7980]

^^ Correct. However, Leupold does make a 'Long Range' STD base, which has a 20 MOA Cant, Part #51734 that will fit STD Rings.

 

[Danep21]

Amazing GIF.. hahaha

 

[J!m]

^^ Correct. However, Leupold does make a 'Long Range' STD base, which has a 20 MOA Cant, Part #51734 that will fit STD Rings.

Yes they do!

My plan is this base with the (correct height) rings, align and weld them as was done on the Redfield 40X/700SA base o the M40 and M40A-1 with the Redfield 3-9 scope. Sort of an "old meets new" situation. 30mm main tube and 20 minute base, but looking like the Redfield mounts and welded as the USMC did.

So my next question is, how high is the Leupold base? Believe it or not, I still have not heard back from them...

 

[Danep21]

I would recommend checking your spam folder for a response from them. Leupold bases are appx 1/8" Thick. If you are going with the Mark 4 10x40mm, and STD LR Base, I would recommend STD Medium rings from Leupold. I would also recommend against welding the rings to the base.

 

[J!m]

It WAS in spam, and they recommended the same rings.

Why would you not weld them? I already did a 1" Redfield set. I detailed it at M40rifle.com and it went perfectly. I need a 30mm bar, but otherwise I will align it the same way prior to welding.

 

[Danep21]

I personally wouldn't, simply because 1.) it will void any warranty you would have from Leupold on the Rings and Bases, and 2.) that will make them really permanent... lol. IF you insist on doing that, I would definitely recommend making sure you are able to zero the scope on the rifle first. THEN, obviously, remove the scope and do so.

 

[J!m]

Well, the way I do it is to chuck up a bar in the lathe and indicate it with the carriage to zero run out.

Then i mount the ring/base assembly to the rod.

Then i I tram the base once I verify the mount holes are parallel to the long edge of the base.

Once the base and bar are within 0.001", I lock the windage screws.

Then i I remove the assembly from the chuck (still together) and tig weld the rings to the base.

Min the case of the 700sa base, the front ring also gets a scallop on the front so the front mount screw can be installed.

As as far as I can tell, this is exactly how the armorers did it back in the day.