Turns out the Revell Viper model has the guns rotated so that the triangular projections on them are vertical when they should be horizontal.
And those projections should be hollow at the centers; they were not.
And the struts holding the guns were almost 2mm too long at their forward points, and the gun positioning was almost 2mm too far back on them anyway.
I have corrected this on my model:
Other changes/additions I made were more of an optional thing, but the kit, as is, ain't as perfect as I'd assumed.
An FYI for fellow modelers.
*Bonus pic: My finished Raider with corrected weathering & laser hit on wing:
Later, my Colonial peeps!