View Full Version : A.R.M.S. M1A mount, what needs to be filed?

April 16, 2008, 19:52
I've read for out of spec SAI M1A receivers A.R.M.S. mounts must be modified to fit. Which areas usually need to be machined/grinded down to make it fit? I also read that usually you run out of windage due to far left placement when the A.R.M.S. mount is forced to mate up with an out of spec receiver. Pics would be of great help if you have any, thanks.

April 17, 2008, 17:30
To fix the issue remove the receiver from the firearm and install a LRB receiver in it's place. :rofl:

J/K, kinda. :beer:

Generally speaking the grooves on your receiver are too shallow, so the rails on the mount are too tall for your receiver. You can mill the rails on the mount down so they will mate the receiver on the sides of the rail/groove interface, without bottoming out.

Alternatively I believe SEI offers a service to mill your receiver into specification, for a substantial fee. In this case you may be better off following option 1 above.

April 17, 2008, 17:45
If you have this kind of problem you can send your rifle back to SAI. They are usually pretty good about their lifetime warranty up to and includeing replacing the receiver if need be.

On the other hand, Sadlak Inc. makes a great mount for the M1A in aluminum, steel and titanium. They also offer a free receiver inspection kit with their mounts and will custom fit their mount to your gun based on the measurements taken from the inspection kit.

More info here: http://www.sadlak.com/si_m1a_receivers.html

and here: http://www.sadlak.com/si_m1a_receivers.html

and here: http://www.sadlak.com/si_custom_sm_fitting.html

April 18, 2008, 23:25
I will be happy to do the needed mods on the ARMS mount for you if you will pay shipping. 90% of the time the Mount will fit the receiver...the ARMS mount has a small web underneath the front of the mount at the angle that makes contact with the top left of the reciever.

I have done several for my own rifles and for others. It is only a dremel job underneath the forward left side of the mount. You will see a web that breaks the angle...This is what contacts the upper left front side of the Receiver. I dremel and then check with a sheet of paper as I relieve the Mount.

On all my ARMs I have never had a problem on 2 SAI receivers, nor on a Poly or an Armscorp. The fitting took me about 15 minutes including the touch-up.

I have shot M14 rifles since 1983 and I have done all the work on mine including bedding and NM mods...I was taught bedding by Gus Fisher and use his Coat hanger method.

let me know I would like to help in anyway I can.


May 01, 2008, 22:26
Sounds great, E-Mail sent.