JimTom wrote:I have just been doing a bit of research and my rifle, although proofed REP, actually has a JM serial number. It was manufactured in 2009 which was prior to Remington taking over manufacturing and moving from Connecticut to New York. I am wondering if the components were manufactured by Marlin then it was assembled, drilled / tapped and proofed by Remington?
The fact that the the receiver has a Marlin serial number suggests that the receiver was fully finished prior to assembly and perhaps then the assembly was completed with a Remington made barrel.
The receiver would have been drilled and tapped in a dedicated fixture on an automated machine so the likely hood of gross error is small although there may be a slight allowance for tolerance. A gross error should have been found in inspection and the receiver should have been scrapped or reworked prior to serial numbering.
The same can't be said for your picatinny rail which as likely as not, irrespective of brand, could have come from a Chinese sweat-shop.
All I can suggest is you try a reliable test for alignment.
A simple test which can be done with very basic equipment.
Take a small piece of white paper about as big as the receiver top and screw in the mounting screws into the receiver through the paper.
Now bring a straight edge, like a 300mm steel rule, up to the screw heads and look down. Depending on which side you approach from you will see a gap on the two inner screws or the two outer screws if the holes in fact are out of alignment. The white paper allows you to easily see a gap. This method will allow you to see a gap as little as 1 or 2 thou which is negligible.
If the gap is larger than say 20 thou (half a mm) which can be approximated with a feeler gauge then the strategy to follow is to establish if three of the screws are in line and then doctor the rail to accommodate the fourth screw, as has been suggested by others.
A more enlightening test would be to see how well each of the screws aligns with the centerline of the bore but that is probably beyond the scope of this discussion.