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Posted by KWA [Jim R.] on 24 February 2010 11:50 AM
There have been a couple reports of loose top rails on the SR series and the new 2nd Gen receivers, on standard KM4A1 and KM4 RIS.

After some investigation, we have a quick and easy fix for the loose top rail issue. Apply this fix ONLY if your top rail is loose.

A punch size 1/16
A Hammer 
A Shim or Spacer, size may vary (for our example we use .2 mm) 

Step 1
Separate top receiver from the gun

Step 2
Remove the hop-up and inner barrel out of the gun.

Step 3
Rest the top receiver on it's side, locate the roll pin in the front and drive the pin out with punch and hammer.

Step 4
Remove the pin and keep in a safe place.

Step 5
Pull the charging handle back slightly and push the top rail backward.

Step 6
Once the top rail slides back, you can lift the rail up from the front and remove it from the receiver.

Step 7
Place a shim to act as a spacer in the top front of the receiver. You might need to try different sizes depending on the gap.

You can add a drop of glue to secure the spacer/shim. Optional!

Step 8
Place the top rail back on receiver.

Step 9
Make sure the rail is lined up, flip the receiver to the opposite side.

Step 10 
Place roll pin back in receiver and line up with top rail.

Step 11
Drive roll pin back in receiver, and the rail should be secure. 

Depending on the size of the shim or spacer, it might be a little big and stick out in the front. You can file it down or use a smaller size.

Let us know if you have any further questions. 

To view the forum discussion, click on the following link.

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