I am putting an ARMS #18 mount on my m1a, and I see that almost everyone has one with a scope. Does this not interfere with the ejection of the spent cassing? It looks like there would be a problem of the shells hitting the bottom of my Leopold scope, is this not the case?
Ejection Issues?
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Yes, it's a fairly common problem when you put a scope on an M1A. The more expensive mounts have an angle to them that helps allow the brass to clear the chamber area. But the lower the mount the better the chance that you will get cases stuck in the action.
The scope ring nuts can also cause a jam problem but usually turning the nuts on the scope rings so that they are on the left side of the rifle and spreading the rings as far apart as possible will resolve things.
If you still have problems then changing the ejector spring or grinding a little off the spring can change the ejection angle of the case and eliminate any jamming issues. You may still get brass marks on the bottom of the scope but it wont hurt anything.
The scope ring nuts can also cause a jam problem but usually turning the nuts on the scope rings so that they are on the left side of the rifle and spreading the rings as far apart as possible will resolve things.
If you still have problems then changing the ejector spring or grinding a little off the spring can change the ejection angle of the case and eliminate any jamming issues. You may still get brass marks on the bottom of the scope but it wont hurt anything.
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Go slow and take your time. Make sure the forward pad is fully retracted and when you go to put it down just barely make contact with the receiver, do not crank on it, you'll make the rail twist.
Once done, DO NOT assume the rail is straight.
After you get the mount on, run a string from the front sight to the rear sight and see if the mount is straight or pointing off in some weird direction. If it's going some weird direction look for contact between the mount and the receiver. I've seen weird contact between barrel rings and the mount making them go up and left. I've seen the clip guide dovetail push the mount down and too the left. Either condition is fixable but takes some effort.
Once you get it fairly straight and looking good, mount your rings as RAMMAC suggested, nuts on the left with as much space between the rings as the scope will allow. Torque the bases to the correct specs.
I recommend lapping at this point but it's up to you.
Drop the scope in and lightly tighten the cap screws. Adjust the scope front to back to get the proper eye relief. Tighten the cap screws a little more. Level the scope and torque the caps to the proper spec, watch the scope level to keep from canting the scope to one side or the other.
Done.
Wow guys, thanks for all the help and input, but I just found someone selling an ARMS #18 Split mount, the old school one. So I guess the ejection issues will be greatly minimized with that mount, but I will still follow your directions. Thanks again guys!
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