I split this off the jig rental thread so more people will find it....
I am still at work (yea 9PM --->>
)
as I said in my e-mail originally, the flat i had built up was square on the bottom better then yours but as long as you can fit your parts it likely isn't a huge issue. Given you still have the jig, can you put it back in the gug and press it down more to get it square? I assume the bottom plate must have not been tight enough to allow this to happen?
As for the upper rails, when you fit the receiver to your bolt you will have some material to work with to get things centered better... Do you happen to have an AK or finished Ak receiver to compare yours to? as long as you have enough rail to support the carrier after you get things cut to size you should be fine...
Now, are the rest of your holes centered OK? if your upper rails are off I would worrt that the rest could be off too? I am also curious if this has to do with the rounded bottom... my flats didn't have these issues when I used either of the two jigs before I sent them out...