ARM #18 and Jams

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dd_M14

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Put the ARM#18 mount on my poly with an old 2x red dot I had. The mount went on with no issues, but the clip guide was a pain. After 10 rounds ... ejected case jams. After another 7 rounds, a second jam. The other shells eject out front right at 30 degrees as before. The second jammed shell case took a bit of twisting to get it free. I think I may need to grind the bottom corner of the mount to give another 0.5 mm space??
Suggestions....
 
A known issue with the ARMS 18 mount. It's low over the receiver and you need stronger extractor and ejector springs such as Brownells sells to eject the rounds.
 
My understanding (45ACPKING jump in any time) is that the Norinco bolts come with stiffer extractor and ejector springs than USGI ones. With low scope mounts the shells can bounce off the bottom of the mounts and back into the top of the receiver causing jams. Replacing the springs with USGI spec ones (ie from Brownells) usually gets rid of this issue. Others have had success cutting coils from the springs but consult with someone who knows about these rifles first (like the character cited above).
 
I have the arms18 and so far no ejection issues and I've done nothing to the bolt.

Though I have no optic mounted yet, so perhaps your rings are getting in the way?
 
I realize I'm jumping in a little late here but I'm awaiting delivery of a Springfield M1A loaded and have been doing much research on all the mounts out there. From what I am reading the jams are a possible result of the stiffer springs in the Norinco. Has anybody had any issues with this mount on a Springfield? I like the idea of installing the lowest mount possible due to the cheek weld issues as I have no need for the irons when optics are installed. Any other solid mounts out there that are nearly as low as the ARMS 18?
 
i don't know how many arms 18 mounts have been sold and fielded in the USA where this product has been on the market for a great many years, but I'd say thousands and it still remains one of the top choices for scoping this rifle. ANY m14 type rifle, usgi, m1a or chinese has the potential to jam with an arms 18. sometimes it's where you put the rings often it's the ejection profile..... if it shoots the brass out and forward..... you are going to get a jam.
if ANY of these rifles, chinese or american jam by trapping an ejected case between mount and oprod..... a spring trimming may be required. as satain says, 2 coils of the smaller extractor spring and 3 coils off the ejector spring, seems to be the ticket with chinese bolts. This chamges the ejection profile and turns the cases out more up and to the side. On my rifle the brass actually comes back away from the receiver.
 
I had this problem on my SA M1A when I had a scope installed with low proflie lever-loc quick release rings. Problem disappeared when I used TPS HRT rings - so, try a ring change before anything else.
 
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