A5 top rail

[Lt.Col.Vortex]

I posted this on the Spec Ops forum, but couldn't hurt to post hear too.


WARNING: This is a "cut in mod". Meaning that this is a gun frame mod that will require you to permanently change the design and look of your marker.

Materials needed:

A measuring device that measures in MM.

Scotch tape.

A 5mm round chainsaw file( I think that most are 5mm). 2 files are recommended as they are some what brittle and will wear quickly, but 1 is fine.

A hack saw with a fine tooth blade. preferable one that is used to cut metal.

NOTE: The internals should be removed to prevent shavings from entering the marker, and the marker will have to be reassembled and worked on int one piece to prevent unevenness.


You will first need to tape off the top of the 7/8" rail on your A5. The TOP rail is the 3/8" rail. These rails are called dove tail rails due to there shape. Taping the TOP of the 7/8" rail will prevent the file from doing too much damage to the rail.

Next you will need to measure out your rails. The rails are 5.23MM wide and 10.o1 MM from center to center. But for this build, 5 and 10MM will do fine. I have had no problems so far with mine. This is a site that has the measurements, http://en.wikipedia..../Picatinny_rail You will need to measure out from one of the edges of the rail to start with. I chose the back of the top rail and it ended up within 1MM of the other edge of being even. So you will not need try and figure out center. Measure out 10MM from the edge and mark with a marking device. Continue with this until you reach the other end.

Once you have measured and marked the top of the 3/8" rail, you will need to be VERY careful and cut a small indentation with the hack saw. This is the point of no return. This cut will help guide your file so it doesn't weaver from the mark. Make sure that the cut is strait to prevent wondering.

Next its time to file in the rail. Simply start slow and use full strokes when filing. This will keep the file strait and prevent the life of your file. File until you get close to the tape. Then next file slowly down to prevent scratching the tape off and marking up the top of the 7/8" rail. Continue down the line until you are done. Try and keep the file 90 degrees to the gun at all times. This will prevent the groove from becoming greater than 5MM.

Once you are done, clean the shavings off and repaint the exposed metal. I recommend taping off like you did for the filing so only the grooves get painted.

And that's it!! This will allow you to mount 7/8" picatinny mounts to your A5 without putting on a riser or after market parts.

[Lt.Col.Vortex]

Hear I have the A5 in a vice with the internals removed. I also have the 7/8" rail taped off to help prevent scratching.

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[Lt.Col.Vortex]

Hear is the rail marked out every 10 mm.


Note that the whole rail is just under 12mm( only by 2 mm), so I space out the first mark 1 mm back. This will make the rails more even.( Note: your gun might be a bit different in length).

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[Lt.Col.Vortex]

Hear I have scored the marks with a hack saw to act as a guide for the file.

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[Lt.Col.Vortex]

Hear is a side shot of the groves being cut.

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[Lt.Col.Vortex]

After you file out all the groves, your done. Just remove the tape and clean up any sharp edges with some fine grit sand paper( 120-400 grit).

If you notice, not all the groves are evenly spaced. This is caused by file wondering. This is OK, so long as your groves are 5mm wide. The distance between the groves in not too important for mounting. This could only be correctly done through a machine. As long as your groves are filed 90% to the marker, and you used the right file size(5mm), you are in the green.

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