Smacking an ACOG after adjustment - is it really necessary?

[T2C]

I don't see the behavior in other prismatic scopes. They track with each click like a conventional scope.

Thanks for the detailed explanation. I meant brand name and model number of scopes like the ACOG that do not require tapping to verify the prism is at rest.

[Hochsitz]

Thanks for the detailed explanation. I meant brand name and model number of scopes like the ACOG that do not require tapping to verify the prism is at rest.

Sorry, the only experience I have doing this test with prismatic scopes is the ACOG, HAMR and Leupy "Prismatic". I'm more red dot/low mag variable myself so I just haven't handled a great variety of product in this arena. The ACOG is so darn prolific I felt the need to fully understand it and how it works the way it does.

[Rackit]

I'm new to the USMC grunt world but this practice caught me off guard. From Parris island to SOI they teach you to give it a slap after adjustments. I never have on my personal ones. It can't hurt the ones we train with though, those things are beat the hell up.


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[Eurodriver]

Do they spend any time at MCRD teaching iron sights anymore?

[Failure2Stop]

I'm new to the USMC grunt world but this practice caught me off guard. From Parris island to SOI they teach you to give it a slap after adjustments. I never have on my personal ones. It can't hurt the ones we train with though, those things are beat the hell up.


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As explained above, the practice is needed to set the prism for zero retention.

[Brahmzy]

Sorry to necro this one.
I own and have owned a LOT of ACOGs. Most have been the Compacts - TA44, TA45 & TA47.

This has been an issue with most of them for me.

Let me describe what I have seen - I just experienced this again in a brand new TA44 and a new TA47.

While adjusting both windage and elevation on both of these new scopes, I can only describe the process as random and frustrating.

Example when adjusting windage while rifle is in a tight rest I can see the exact result of the reticle’s movement while adjusting the turret.

Whether moving right or left, the reticle would not move correctly according to the turret adjustments. As I would adjust the reticle left, it would move left for 2 or 3 clicks and then start moving down and then stop with the next few clicks and then with the next click it would “jump” to where it should’ve been smoothly and predictably moving through the clicks. It’s like there is a tension that builds with a certain amount of clicks and then releases with additional clicks. This behavior is easily repeatable with multiple new and older Compact ACOGs. It makes zeroing extremely frustrating and unpredictable. Some have been worse than others, but the majority have had this issue to some degree. Keep in mind I am nowhere near the “end of adjustment” danger zone with any of these.
I really think there is something to tapping the turrets after each adjustment is made. I haven’t been able to see if the tapping “moves” the reticle to it’s proper position as the rifle has been moved off of it’s original POA due to the tapping. I suppose I could put these ACOGs in a bench vise to study this better.
I am going to contact Trijicon CS and try to get a technical explanation behind this and see what their current recommendations are.
Again, these are all brand new ACOGs, bought by me, and most exhibit this weird turret behavior. A large sample size, manufactured over many years. This removes the defective single sample argument.

Any thoughts?

Lots of others have described sorta similar behavior.

Post #4 of this thread kinda nails it:

https://www.thehighroad.org/index.ph...ighter.597732/

EDIT: So the further I dig into this, the further the tapping requirement seems to be a thing. TONS of threads on this exact problem. Folks saying “you’ll be chasing your zero around” if you don’t whack the turrets after adjustments - this describes exactly what I’ve experienced. Some guys bring a rubber mallet with them while zero’ing their ACOGs. Others mentioning “sticky internals” while trying to adjust.

This definitely helps back up my own experiences. One thing’s certain, if you can get the ACOG properly zero’d, it will hold that zero indefinitely. My guess is this issue is somehow a trade off / compromise for offering that bombproof zero-hold capability.