Rifle Scopes Anyone have the backstory on oddly specific ring heights?

[tinycrumb]

I was doing some research on rings/mounts today for some CNVD use and noticed that both my Geissele and Nightforce mount have heights of 1.54”. This got me thinking… what’s the deal with this? Why do we have things like this 1.54” and 1.93” instead of just 1.5” and 2”?

My first thought was some metric conversion but neither of those are clean conversions.

Any ideas?

 

[tinycrumb]

You didn’t comprehend my question at all. I fully understand that and own said clip-ons. I’m asking why we have such specific heights like “1.54” and “1.93” instead of round numbers like “1.5” or “2””. Where did those .04 and .03 come from. They seem to be standardized at this point.

 

[tinycrumb]

I think your not following brother. I travelled to Brazil last year, to sell NVGS. When a solicitation is placed into public (think of SAM.gov) it is very specific , to the millimeter. For example: one of the contracts I was thinking of placing a bid for had exact objective lens sizes; not the outer ring itself, but the glass inside the objective.

Hope this helps you to understand.
Kind regards
Felipe Bastos
EliteUAS

I am following your response. But you’re not comprehending my question. I’m specifically asking the origin of the 1.54” and 1.93” heights.

If your response is it’s that specific height because military clip-ons are that height… that still doesn’t answer the question. Why did they make the clip-ons that height?

If your response is that both the clip-ons and the optic rings were made that height because of a military contract solicitation… then who wrote it and why did they choose such oddly specific heights?

I’m not interested in why companies keep propagating the spec… that’s pretty obvious… for the reasons you stated. I’m interested in the origin.

(And BTW, I’m not aware of any CNVDs that are 1.93 height lol)

Someone, somewhere in history decided these heights. It could have just been random or an accident and we’ve stuck with it ever since. But that’s where my curiosity is. I’m purely interested if there was some historical backstory or context to it or if it was just random. I didn’t think it was a complicated question.

 

[srt-4_uk]

50mm= 1.93
40mm= 1.57
No need to measure ring height to the thousands

 

[tinycrumb]

50mm= 1.93
40mm= 1.57
No need to measure ring height to the thousands

Umm… am I crazy?

 

[Trigger Monkey]

1.93" mounts exist because back in the day there was a solicitation for a LPVO mount that could clear a PEQ. After some trial and error that was the height settled upon that kept a S&B Short Dot high enough to clear a PEQ but low enough that it wasn't weird to shoot with.

Like that:

After that I guess it was just institutional inertia that's kept them around.

As far as 1.54" heights go, I've heard that it has to do with the height of an Aimpoint and the issued mounts coming out to 1.54" tall and that was the height needed for mounting NV's to the weapons.

Long story short the specific heights came down to military requirements for compatibility with night vision and IR aiming devices and the rest of the industry just sort of followed suit because that's what the military is doing.

 

[cjs88]

If the heights were chosen by the military, it was probably ergonomics

 

[TC.TURTLECREEK]

why are railroad tracks 4' 8.5" wide? same principle, but a little older lineage: https://aviationhumor.net/the-us-standard-railroad-gauge-is-4-feet-8-5-inches/

 

[tinycrumb]

1.93" mounts exist because back in the day there was a solicitation for a LPVO mount that could clear a PEQ. After some trial and error that was the height settled upon that kept a S&B Short Dot high enough to clear a PEQ but low enough that it wasn't weird to shoot with.

Like that:

View attachment 8035149

After that I guess it was just institutional inertia that's kept them around.

As far as 1.54" heights go, I've heard that it has to do with the height of an Aimpoint and the issued mounts coming out to 1.54" tall and that was the height needed for mounting NV's to the weapons.

Long story short the specific heights came down to military requirements for compatibility with night vision and IR aiming devices and the rest of the industry just sort of followed suit because that's what the military is doing.

That’s fascinating about 1.93. And still seems oddly specific to me. Seems like it would have made sense to just round it off to 1.9 or 2 and call it a day… but maybe that’s unnecessary in today’s manufacturing environment.

The story about the Aimpoint seems interesting / slightly suspicious. Most of the older NV solutions I can think of were for scopes, not red dots. But maybe there was something for the Comp M2 or 5000 that I can’t think of? Would love to see some documented history of this… it’s starting to tickle my nerd brain.

 

[tinycrumb]

why are railroad tracks 4' 8.5" wide? same principle, but a little older lineage: https://aviationhumor.net/the-us-standard-railroad-gauge-is-4-feet-8-5-inches/

Hahaha, I loved this. Exactly what I was hoping was the case with this.

 

[Trigger Monkey]

LaRue Tactical was the one that originated the 1.93" mount, you could try to get some background info out of them.

Regarding the Aimpoint, I believe the M68's with the QRP mount came to 1.54" above the rail and the rail mount for the PVS-14 was designed around the same so a soldier could mount his PVS-14 to the rifle. It wasn't often used but it was an option.

 

[tinycrumb]

LaRue Tactical was the one that originated the 1.93" mount, you could try to get some background info out of them.

Regarding the Aimpoint, I believe the M68's with the QRP mount came to 1.54" above the rail and the rail mount for the PVS-14 was designed around the same so a soldier could mount his PVS-14 to the rifle. It wasn't often used but it was an option.

Makes sense! Thank you!!