Ive installed the barrel into the receiver. It looks like all is lined up properly the barrel nut opening is centered to the receiver hole.

I can pass a rifle length tube thru with lite resistance from the rear of the receiver and it lines up with the hole in the front sight base
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BUT I can't get the carbine tube to line up and go into the receiver it's off to either side a little more than 1/16 inch at the front receiver hole. It's going in at a angle because the front sight base prevents me from lining the tube up to go straight into the receiver.  The sight is thick and  causes a offset angle of about 1/4 inch at that end of the tube that throws it off at the receiver.

I suppose I could knock the taper pins out and remove the front sight base then install the tube in the base then reinstall the front sight.  Then it would go straight into the receiver. But sometimes taper pins are a real pain to remove.

Parts are new Colt M4 receiver and Colt 14.5 inch Socom barrel pinned and welded to 16. New Carbine  length gas tube.

What have I got messed ups here?

Watch a few YT vids.

It's pretty straightforward work.

You just wiggle it in.

Push harder