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Posted: 9/12/2003 2:07:58 PM EDT
Okay,I own an ARMS 38ex,an ARMS M68 and an ARMS 40A BUIS.Needless to say, I like their products.I am wondering though,why do all the above products slide back and forth on the rails after they have been mounted? It takes a bit of pressure,but they all will move,even the M68 on the 38ex,which eliminates the possibility of an out of spec rail.Anyone else wonder about this?Is this engineered into the design for some reason?Regards,Phil
Link Posted: 9/12/2003 2:55:31 PM EDT
Ive never experienced the least bit of movement in my ARMS parts. Hmm....
Link Posted: 9/12/2003 3:34:53 PM EDT
[Last Edit: 9/12/2003 3:35:32 PM EDT by DevL]
All ARMS throw levers and other products do this. They are designed to be able to fit into the rails even when they are dirty and full of crud. If it fit 100% tight and ther was anything in the rails under real field conditions you would not be able to slide the part together. This is the difference in having a field ready unit and a target ready unit. Dont worry though it wont damage anything to have that small amount of fore/aft play, it wont ruin your zero and is completely normal.
Link Posted: 9/12/2003 3:37:04 PM EDT
What type and brand rails are you mounting these ARMS items onto? My #40 BUIS was VERY difficult to mount onto the rails on my Bushmaster M4 and wouldn't budge even without being tightened. I've never heard of this type complaint with any ARMS product before so I would first suspect something amiss with the rail itself.
Link Posted: 9/12/2003 3:37:33 PM EDT
I thought we were talking [b]after[/b] mounting.
Link Posted: 9/12/2003 3:46:59 PM EDT
All ARMS throw levers move fore and aft. If it does not do this your rail is out of spec and is too narrow.
Link Posted: 9/13/2003 8:30:40 PM EDT
Yes,after mounting my ARMS 22M68 on my ARMS 38ex,which eliminates the possibility of an out of spec rail,it WILL slide fore and aft,after the throw lever has gone kerplunk and is locked down tight.I won't worry about it,Thank you all for your replies.Devl makes perfect sense,that is kinda what I figured.If I want a semi-permanent totally rigid mount,I can shim it.
Link Posted: 9/13/2003 10:19:58 PM EDT
[Last Edit: 9/13/2003 10:41:42 PM EDT by Lumpy196]
I own two ARMS 22M68s and neither move when locked down on a 38EX or on a Bushmaster upper. Nor does my 19S that my TA31 is mounted on move, nor does the ARMS throw lever mount on my Surefire 962 flashlight move.
Link Posted: 9/14/2003 6:44:47 AM EDT
There is a small amount of movement in my #35 base on my SPR-like rifle. It is noticeable after the mount is removed and replaced, as the POI wanders around maybe 1/2 to 3/4" at 100 yards. Not enough to worry about on any "realistically" sized targets, but it makes it hard to hit those quarters with the first shot. After 20-30 rounds, it settles in and the POI remains constant.
Link Posted: 9/14/2003 12:39:11 PM EDT
[Last Edit: 9/14/2003 12:43:07 PM EDT by mark5pt56]
I had an Olympic and when the #19 was locked down on it, it would move. It doesn't on my Colt or Bushmaster. Any A.R.M.S. base for that matter(#38/SIR)I checked another Olympic at a shop and it to would allow movement after the mount was locked. Also, the so called 1913 rail on GG&G's offset light adapter, isn't 1913. My M962 locks tight on the SIR, but not on that. I would check the pads, they do wear after awhile and may need to be sent back. A.R.M.S. will be kind to you in this regard. Mark
Link Posted: 9/14/2003 5:36:06 PM EDT
From my experience, the ARMS products are very accurate to the mil spec because of gov't contract inpections. However, if you buy an after market receiver that isn't to spec., you can possibly get movement. If a #38 rail or #40 rear sight moves afyter tightening, you have a real undersize receiver dovetail and should replace it as it isn't even close to spec. and nothing will work well on it. Good shootin, Jack
Link Posted: 9/14/2003 11:23:53 PM EDT
From what I have found the movement is identical on a throw lever to what you can do before you lock the arm down. It the clearance between the recoil lug and the rails. The only difference is that after you throw the arm friction tends to hold it in place. If you push hard enough fore/aft the unit will move once you overcome the friction. This hold true for for all the Bushmaster and Colt flat tops as well as KAC rails I have tried. There is always movement. However some throw levers are a so tight when locked it takes a real effort to get em to move but if you attach and remove em enough it gets easier.
Link Posted: 9/15/2003 5:06:34 AM EDT
Just noticed this yesterday. I love it when you guys can answer something for me before I even ask! [:D] Btw, what I experienced was the 22M68 moving fore and aft. I've already had it on and off quite a few times (every time I clean) so that may be why I'm just now noticing it. Glad to hear it's nothing to worry about.
Link Posted: 9/15/2003 11:25:45 AM EDT
Movement BEFORE securing the lever, yes, but afterward, I dont experience this with my ARMS mounts. Odd.
Link Posted: 9/15/2003 3:44:17 PM EDT
Link Posted: 9/16/2003 1:00:12 AM EDT
Actually, didnt new_arguy guy say that ARMS recommends snugging against the rear of the slot? I could be completely wrong.
Link Posted: 9/16/2003 2:06:36 AM EDT
[Last Edit: 9/16/2003 2:26:48 AM EDT by bsbg]
Originally Posted By Lumpy196: Actually, didnt new_arguy guy say that ARMS recommends snugging against the rear of the slot? I could be completely wrong.
View Quote
That was for the M900, which can have a lot or rearward pressure exerted on it.
Link Posted: 9/16/2003 2:09:04 AM EDT
Ohhhh yeah. See? I should just go to bed.
Link Posted: 9/16/2003 10:31:03 AM EDT
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