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5/24/2012 6:01:21 AM EDT
Why does the below model have the mount locking screw-knobs on the ejection port side of the weapon and most all other ACOGs have the mount locking screw-knobs on the other side of the gun?

TA31RCO-M4CP: Trijicon ACOG 4x32 Scope with BAC USMC Rifle Combat Optic (RCO) for M16M4 (14.5 barrel)
Link




Most models have locking knobs on the left side as pictured below:

5/24/2012 6:03:02 AM EDT
[#1]
Don't waste any more time worrying about it. Just buy a LaRue mount and have no more worries forever.
5/24/2012 6:04:13 AM EDT
[#2]
Plus (and don't quote me since mine came with an LT mount already) you should be able to just flip the mount around when you attach it.
5/24/2012 6:06:00 AM EDT
[#3]
Quoted:
Plus (and don't quote me since mine came with an LT mount already) you should be able to just flip the mount around when you attach it.


you can, there is a hex screw holding the mount to the optic. you can flip it around however you prefer
5/24/2012 6:07:10 AM EDT
[#4]
You can mount the scope in either direction on the mount.

IMO, you don't need a removable lever mount for a scope this reliable, unless you are actually deploying.  So, I wouldn't spend the money on a fancy mount.
5/24/2012 6:07:20 AM EDT
[#5]



Quoted:


Why does the below model have the mount locking screw-knobs on the ejection port side of the weapon and most all other ACOGs have the mount locking screw-knobs on the other side of the gun?


For export to the southern hemisphere only.



 
5/24/2012 6:09:09 AM EDT
[#6]
Quoted:
You can mount the scope in either direction on the mount.

IMO, you don't need a removable lever mount for a scope this reliable, unless you are actually deploying.  So, I wouldn't spend the money on a fancy mount.


we don't have BUIS for our M4A1s with ACOGs
5/24/2012 7:21:54 AM EDT
[#7]
Meh, just wring those gargantuan nuts off, snip the studs down and use 10-32 nuts, and it doesn't matter which side they're on; they'll be out of the way.

5/24/2012 7:24:04 AM EDT
[#8]
Quoted:
Don't waste any more time worrying about it. Just buy a LaRue mount and have no more worries forever.


I bought a LaRue ACOG mount and stopped using it. I prefer the standard ACOG mount because of these observations after using a LaRue mount:

1. The LaRue mount locks against the rail at only two tiny points of contact area vs. the ACOG mount which locks against the rail for the complete length of the mount. So less than 1/4" of total contact area for the LaRue vs. about 3.5" of total contact area for the ACOG mount.
2. As the cam levers on the Larue mount engage and tighten against the rail, they rub against the rail and wear the rail. Aluminum is soft and wears quickly with high friction. On my rifle the black anodizing was worn off the rail at the contact points after taking the scope w/ LaRue mount on and off a few times.

I realize the LaRue mount is very popular and very well liked.
5/24/2012 7:26:57 AM EDT
[#9]
I prefer the knobs. Don't need a special tool to take them off and it locks on nice and strongly. If you want to tighten them down but don't want to mar them up then just use the grip portion of vise locks and tighten them.
5/24/2012 7:30:16 AM EDT
[#10]
Quoted:
Meh, just wring those gargantuan nuts off, snip the studs down and use 10-32 nuts, and it doesn't matter which side they're on; they'll be out of the way.

http://farm6.staticflickr.com/5120/6923753466_29d256301f_c.jpg


So now you need tools to take the ACOG off and use your BUIS?
5/24/2012 7:33:37 AM EDT
[#11]
Quoted:
Quoted:
Meh, just wring those gargantuan nuts off, snip the studs down and use 10-32 nuts, and it doesn't matter which side they're on; they'll be out of the way.

http://farm6.staticflickr.com/5120/6923753466_29d256301f_c.jpg


So now you need tools to take the ACOG off and use your BUIS?


Yea. I like the idea, but needing a a socket....no thanks. Knobs are good enough for me.
5/24/2012 8:29:55 AM EDT
[#12]
Quoted:
Meh, just wring those gargantuan nuts off, snip the studs down and use 10-32 nuts, and it doesn't matter which side they're on; they'll be out of the way.

http://farm6.staticflickr.com/5120/6923753466_29d256301f_c.jpg


There ya go.

Get ya some fancy black finish 10-32 nuts at McMaster-Carr, add a couple of black finish washers, put a tiny dab of blue Loctite on the threads before assembling, and you're set.
5/24/2012 8:44:25 AM EDT
[#13]
Quoted:
I prefer the knobs. Don't need a special tool to take them off and it locks on nice and strongly. If you want to tighten them down but don't want to mar them up then just use the grip portion of vise locks and tighten them.


I take a quarter using pliers to hold the quarter. That works good to get the mount really tight without damaging the knobs

Posted Via AR15.Com Mobile
5/24/2012 8:47:04 AM EDT
[#14]
Quoted:
Quoted:
Don't waste any more time worrying about it. Just buy a LaRue mount and have no more worries forever.


I bought a LaRue ACOG mount and stopped using it. I prefer the standard ACOG mount because of these observations after using a LaRue mount:

1. The LaRue mount locks against the rail at only two tiny points of contact area vs. the ACOG mount which locks against the rail for the complete length of the mount. So less than 1/4" of total contact area for the LaRue vs. about 3.5" of total contact area for the ACOG mount.
2. As the cam levers on the Larue mount engage and tighten against the rail, they rub against the rail and wear the rail. Aluminum is soft and wears quickly with high friction. On my rifle the black anodizing was worn off the rail at the contact points after taking the scope w/ LaRue mount on and off a few times.

I realize the LaRue mount is very popular and very well liked.


Is it truly wearing through the anodizing into the aluminum, or is it just wearing through the dye of the anodizing?
5/24/2012 8:48:39 AM EDT
[#15]
Quoted:
Quoted:
Don't waste any more time worrying about it. Just buy a LaRue mount and have no more worries forever.


I bought a LaRue ACOG mount and stopped using it. I prefer the standard ACOG mount because of these observations after using a LaRue mount:

1. The LaRue mount locks against the rail at only two tiny points of contact area vs. the ACOG mount which locks against the rail for the complete length of the mount. So less than 1/4" of total contact area for the LaRue vs. about 3.5" of total contact area for the ACOG mount.
2. As the cam levers on the Larue mount engage and tighten against the rail, they rub against the rail and wear the rail. Aluminum is soft and wears quickly with high friction. On my rifle the black anodizing was worn off the rail at the contact points after taking the scope w/ LaRue mount on and off a few times.

I realize the LaRue mount is very popular and very well liked.


Can you take the factory ACOG mount off and return it to the rail without any POI shift?  You can with the Larue, which tells me it has a more consistent and solid lock up.  I've been using these mounts for years with zero damage to my rails.   But, there is nothing wrong with the factory mount either.

To answer the OP, the knobs usually go on the left side of the rifle.  But, some military guys like them on the ejection ports side because the knobs hang up on their gear.   The mount can go either way.  

5/24/2012 8:56:59 AM EDT
[#16]
Quoted:
Why does the below model have the mount locking screw-knobs on the ejection port side of the weapon and most all other ACOGs have the mount locking screw-knobs on the other side of the gun?

TA31RCO-M4CP: Trijicon ACOG 4x32 Scope with BAC USMC Rifle Combat Optic (RCO) for M16M4 (14.5 barrel)
Link

http://www.trijicon.com/images/product_masters/TA31RCO-M4CP.jpg


Most models have locking knobs on the left side as pictured below:

http://www.trijicon.com/images/product_additionals/TA31-CH_additional_popup_1.jpg


I read somewhere that they changed the mount so that the screws are on the ejection port side because when the locking screws were on the other side, they got in the way of slapping the bolt release sometimes. I don't know if that's true but that's what i heard for the reasoning behind that.
5/24/2012 9:00:07 AM EDT
[#17]
Quoted:
Can you take the factory ACOG mount off and return it to the rail without any POI shift?


I haven't tried it, but the ACOG owner's manual says that you can, as long as you reinstall it in the same rail slots.

5/24/2012 9:25:15 AM EDT
[#18]
I just emailed Trijicon and this was their response:

"Only the RCO models are opposite, as requested by the Marines."

I wonder why the Marines want the knobs on the ejection port side?
5/24/2012 9:26:56 AM EDT
[#19]
Quoted:
Don't waste any more time worrying about it. Just buy a LaRue mount and have no more worries forever.


First post and all that!
5/24/2012 9:27:57 AM EDT
[#20]
Quoted:
I just emailed Trijicon and this was their response:

"Only the RCO models are opposite, as requested by the Marines."

I wonder why the Marines want the knobs on the ejection port side?


Someone already said that the knobs get stuck on gear.
5/24/2012 9:35:50 AM EDT
[#21]
i believe I read once it was because of  sometimes under stress a marine or soldier would sometimes reach for his charging handle   and grab the mount by mistake  in the dark or when worked up

not sure how true or serious the problem was but that was the reason I heard

so what if the larue wears on the finish?  do you shoot it or just look at it and use it for a clone to admire?

guns get scratches, dings and wear silver spots when they are used. its life
5/24/2012 6:16:47 PM EDT
[#22]
Quoted:
Quoted:
Meh, just wring those gargantuan nuts off, snip the studs down and use 10-32 nuts, and it doesn't matter which side they're on; they'll be out of the way.

http://farm6.staticflickr.com/5120/6923753466_29d256301f_c.jpg


So now you need tools to take the ACOG off and use your BUIS?
Yep! And I don't need Tools, I need a simple  box-end wrench that's about 2" long and stored in the buttstock. Doesn't matter though, since the likelihood of needing to get to the BUIS before Godzilla squashes me into a stain in the yard is pretty much zero when using an ACOG. The primary reason I even have a set of BUIS on the rifle is because it looks naked without it.

5/24/2012 7:02:08 PM EDT
[#23]
They are reversible, very handy when mounting one to an AUG
5/24/2012 7:27:34 PM EDT
[#24]
Quoted:
Doesn't matter though, since the likelihood of needing to get to the BUIS before Godzilla squashes me into a stain in the yard is pretty much zero when using an ACOG.


I agree.

Putting a BUIS on an ACOG-equipped rifle is like putting iron sights on an ICBM - You ain't ever gonna need 'em.