Screws for Impact M3 bottom rail?

[Michael]

Ok Impact guru's I've got a quick question.

I've swapped out the bottom rail so many times that I forgot if all the screws should be the same length or not?

I just swapped out the Scandanavian Arms rail for the K&L Gen 3 rail and I noticed that 2 of the 4 screws are shorter than the other 2. The 2 shorter screws don't bite much. I'm thinking the SA rail may have come with 2 shorter screws, but I can't remember (and I don't see any spare screws laying around).

Are all your screws the same length?

 

[Bigragu]

Yes all four same length @ M3 x 16

On the M3 parts drawings line item D76

 

[Michael]

I found the original screws. They are in fact longer than the ones used with the SA rail.

Thanks!

 

[kiba]

If you have an early production M3, the 2 front rail screws under the 1st regulator *may* be shorter than the 2 rear screws.

This is because FX incorrectly machined the 2 front holes on the lower action block on early production M3s and drilled them too deep which caused a leak into the 1st reg / bottle air transfer passage. Rather than replace the mismachined lower action blocks FX plugged the 2 front holes with setscrews and epoxy. The setscrews use up some thread depth and leaves less room for the rail screws, so the 2x front screws might be shorter.

I have one early production M3 with the setscrew plugs installed in the front, and one recent production M3 without the setscrew plugs. I have to use slightly shorter front rail screws on the early production gun with the plugs. The later production M3 uses 4 rail screws that are the same length.

The early production M3 doesn’t leak from those 2x plugs, so I haven’t felt the urge to replace the lower action block yet.