I have a CAN mount with 34mm rings on top of a big bore ultimate upper (308). I think I am pretty good on my HOB measurement when I think to myself; Larue is the Dead Center of Precision and they cater/market to shooters that want as close to perfection as possible, so why not get perfect dimensions? Surely their website will have exact center of bore to top of rail measurements on their uppers and top of rail to scope center line measurements on their scope mounts. Nope not on the website.

So I call and thankfully only wait a few minutes to get a rep. He is cheerful and willing to assist! I share my desired information and promptly told he is not "authorized" to provide those dimensions on the upper, but he can share them for the scope mount. I'm so confused, why would a critical number in determining HOB be a secret?

FFS

If you have the mount, and you have the gun, I'm certain you have a ruler.

Your video didn't have the answer to my question of curiosity. Why would that simple yet critical dimension not be freely shared?

Oh wait, in your rush to condescension you missed the SECOND sentence where I stated I have my measurement. I'll use crayons in the future so you can understand.

With the amount of LT104’s out there on 7.62 and 5.56 rifles I’d hazard your fine.  

Maybe because that measurement doesn’t mean anything without knowing the mount height, and that varies by manufacturer or even ring diameter, and height over bore measurement accuracy doesn’t have to be exact!

OP, using a basic “ruler” measurement will get you close enough for ELR hits. You can be off slightly (1/4”) and it still won’t impact your results significantly. Plug it into your ballistic calculator and you’ll see. Unless you’re off by 3/4”+, you won’t be able to shoot the difference  with a LaRue inside 14-1500 yards!! At that point, std dev. and ES matter even more.

So, to your question, why don’t they have it listed? Probably because it doesn’t truly matter to be that precise.

You are asking the wrong question. LT doesn’t control what uppers people are mounting their mounts on. I can guarantee that in the past someone called and asked the same exact question. They were given a stock answer. Then they went and measured theirs, 4th owner by the way, and LT was off by 4.3mm. Then they got on the lt forum and GD and went to town on how fucked up LT is that they didn’t know the numbers. Well it turns out the second owner of the gun replace the lt upper with a PSA upper and sold it as is.

My guess is the chip off the consumer block is not worth the cheddar. So the stock answer has to become, we only quote dimensions on the mount, you figure the rest out.

But I’m just guessing.

And yes, I agree with the post above. I pretty much have one number I use for hob for each class of guns. I’ve never seen the need to nail it down.

Maybe someone smarter than me can calculate the correction at 1,000 caused by being off 2-3mm. I’d love to know.

Just ran the numbers for one of my guns at 1,000, hight 1 = 300.6” drop, hight 1-.25= 302.68” drop. I can’t shoot well enough to appreciate that. But the good thing is the drop won’t change so my correction would fix the error.

Best of luck.