Tighten up Swiss Arms upper and lower

MUGEN

MUGEN

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I am just wonder if anyone ever try to tighten up the wiggle on their Swiss Arms?
The original pins diameter is at 5/16" (measured 7.95mm)
Hole size on top half: measured 8.07mm , lower 8.05mm.
0.1mm difference is quite too much unless it is due to location accuracy of these 2 holes.

Anyone ever try to put a bigger pin (8mm slip fit) to replace the original pins, or put two 0.1mm shim at the front pivot? Or wedge at the rear?
Is the lower receiver from NEA much tighter?
 
MUGEN said:
:ar15:Do you know what I am talking about?
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I'm assuming you are taking a page from every AR-15 owners tool kit, and trying to take the slop out of the upper and lower reciever.

My point is as I asked. What are you trying to achieve? The guns are reliable and accurate. The play isn't enough to greatly increase verticle stringing. The sights or optics are on the upper, so reciever play ought not to be a large issue.
 
You're really that concerned about a 3.9 thou gap between the pins and holes in the upper? You know that a picatinny rail locking slot has a tolerance of .206" + .008" to be in spec, right? And the difference you noted is half that...

Sure you could add a 1.8 thou insert around the hole, but are you really expecting to see a noticeable difference in performance? Admittedly the upper and lower on my LMT are fitted together slightly better than on my Swiss Arms, but the Swiss is still fairly good in this respect. Also remember that the Swiss has stamped receivers, not machined.
 
Pretty much any rifle that uses a hinge pin design will have a little bit of play, the amount of play doesn't effect the accuracy enough to be noticeable.
 
Ar180shooter said:
You're really that concerned about a 3.9 thou gap between the pins and holes in the upper? You know that a picatinny rail locking slot has a tolerance of .206" + .008" to be in spec, right? And the difference you noted is half that...

Sure you could add a 1.8 thou insert around the hole, but are you really expecting to see a noticeable difference in performance? Admittedly the upper and lower on my LMT are fitted together slightly better than on my Swiss Arms, but the Swiss is still fairly good in this respect. Also remember that the Swiss has stamped receivers, not machined.
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I understand it won't affect accuracy, but youknow your right hand is holding the grip (lower) while there is play on the upper. I know I know... I know this happens on most top half bottom half guns, but I just want to make it tighter. The play on LMT is much less and is hardly feel it at all (that is one of the best fit AR I have ever tried). And my Tavor does not have this issue at all and I like that better.

Those gear/ sight whatever is being tighten up on a picantinny rail, so this tolerance won't cause any issue (as long as it can get tight). Unless the taper is made under size or the rail profile is out of straightness.
 
My point was that they're pretty well fitted given the design of the rifle. I don't even notice it when I'm shooting, my mind is concentrating on other things. I suppose you could make an accu-wedge type thing that would fit in behind the rear pin, but this would have to be something that you make yourself. I'd also be concerned about it accidentally interfering with the bolt.
 
For me the wiggle between the upper and lower was nothing, but toward the 3000 round mark I think it got worse, either way it became really annoying, and after a while it was too much to take and even though taking a pair of pliers to a $3000 rifle was terrifying, I finally decided to try this idea I had previously found on the Swiss Rifles Message Board http://theswissriflesdotcommessagebo...PE90-looseness

In the thread, the looseness between the upper and lower are discussed, as I said I couldn't stand how loose mine felt, so I tried what this guy suggested in post #3, "The only other thing you can do is carefully bending the front fork part of the lower a little closer." I did this and My upper and lower are now very tight. There is no looseness or wiggle at all anymore. When I did this, I wrapped the fork part of the lower in 2-3 layers of towel so as to not scratch the finish, and then (I cannot stress this enough) "CAREFULLY" bent them ever so slightly tighter together with a pair of vise grips. It worked beautifully. Better than I could have ever imagined
 
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Steve Janes said:
For me the wiggle between the upper and lower was nothing, but toward the 3000 round mark I think it got worse, either way it became really annoying
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Similar ecxperience at around the 2500 ish mark... I'm going to plier my rifle tomorow and see if it works.
 
I tightened mine in a vise.... wrapped the lower to prevent scratches. squeezed the "fork" a bit, test... squeeze a bit more.... perfect.
 
RJD said:
I tightened mine in a vise.... wrapped the lower to prevent scratches. squeezed the "fork" a bit, test... squeeze a bit more.... perfect.
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were talking a couple mm's right? so that when it elastics back it'll have moved ever so slightly
 
winnipegger said:
were talking a couple mm's right? so that when it elastics back it'll have moved ever so slightly
Click to expand...

I wouldn't even try a couple mm's at first, try like 1 mm then see how much it moves it a couple times, then if its not torquing it enough you can increase a bit.

this is one of those things, where taking it slowly is good, if you go too far all sorts of bad things can happen (including warping the steel when trying to bend it back)
 
winnipegger said:
so that when it elastics back it'll have moved ever so slightly
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EXACTLY!!!

winnipegger said:
were talking a couple mm's right?
Click to expand...

Very hard to say, but I would say not even 1mm for mine. But again it was hard to tell, there was a towel wrapped around it and I didn't bust out the micrometer or anything like that.

As F22_RaptoR is saying above, this is something you want to take very slowly.
If you go too far you freakin' screwed, but if you don't go enough then just wrap it up and try a tiny bit more. I had to try 2-3 times before I got it perfect, thought I went to far for a second, but it's just really snug now.
 
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