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9/22/2017 12:11:25 AM
Posted: 9/12/2005 11:47:23 AM EDT
I am unable to easily attach my new ARMS 40L to my new flat top upper.

I see how it supposed to attach with the square post through the rear (I assume) notch.

I am removing the square post completely then pulling pack the charging handle then trying to slide the BUIS forward from the rear.

It get hung up on something before sliding foward far enough to insert the square pin.

Am I installing it wrong?

Should I just hit it with a bigger hammer?

here's a pic

Link Posted: 9/12/2005 12:54:22 PM EDT
its the upper reciever being thick and the arms not having forgiving tolerances

i had the arms#40 and arms throwlever aimpoint mount and none of it would fit my alexander arms beowulf upper.

the coating/annodizing was super thick and prevented the installation of either.
Link Posted: 9/12/2005 1:56:30 PM EDT
What kind of upper is that?

I have a variety of uppers, and don't have any problem switching any of my ARMS gear back and forth between them.
Link Posted: 9/12/2005 2:45:13 PM EDT
The upper is a CMMG M4 type.
I'm considering just pounding it on there then looking for the bare metal spots to see where it's rubbing.
I've contacted CMMG and ARMS but no response yet.
Link Posted: 9/12/2005 3:18:02 PM EDT
I had 2 different ARMS #40 BUIS, one took a lot of filing with needle files to fit any of my uppers, the other fit all without difficulty. They are a great sight but from my experience and others I have read about it is common for them to be to tight.

Just dont wack it to hard and go slow, it took me about 2 solid hours of fit and file to get mine to slide on without restriction.

Nice cat you have there, a little blurry but I am sure it doesnt mind

Link Posted: 9/12/2005 8:12:12 PM EDT
OK, that sounds good.
I'll use the file on the BUIS instead of the upper.
Good idea. Thanks.
Link Posted: 9/12/2005 10:02:51 PM EDT
I used a rusty file on the ARMS, just under the swan symbol.
With a little work I was able to get it in position. The bare metal spots are hidden.

I guess it makes sense for it to fit snug since it's 'position critical'.

The cat checked it out and told me to use loctitie.

Link Posted: 9/13/2005 3:25:33 AM EDT
if you are gonna file anything make sure you use some loctite.

Link Posted: 9/13/2005 4:18:35 AM EDT
[Last Edit: 9/13/2005 4:38:51 AM EDT by JKH]
While the cat obviously has an afinity for black rifles I think he may have misjudged the need for loktite

The lock bar on the sight will hold it where it needs to be, simply use a quarter to snug the nut and you wont have any problems, loktite wont be necessary.

What kind of groups does Mr Kitty get with that rig?

EDITED TO ADD: I have to assume from that last picture that Mr. Kitty is not a south PAW

Link Posted: 9/13/2005 4:26:37 AM EDT
[Last Edit: 9/13/2005 4:29:10 AM EDT by VTDefender]
Give A.R>M.S. a call.
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