Im not familiar with the scallop your talking about. A pic would be helpful.
If its something added or milled by someone after manufacture, it could be a problem.
But, theres alot more information needed to diagnose the problem.
The type of receiver. LA, SA, CRF, Push Feed?
The type of magazine/floorplate, if its factory or been modified, type of stock?
I used to run a gunsmithing type business, but got out of it and made silencers for about 5 years. Now i make machine tool parts except for occasional gun work for a few long time customers.
My degree is in Engineering Technology. I focused it as much as possible towards Mechanical Design. All my technical electives, in addition to the core stuff like statics, dynamics, engineering mechanics mech design 1, mech design 2, mech design 3, tool design, power train design and a few classes on cnc turnin, milling and programming.
Ive heard Mechanical Egineering Technology has quite a few differences from a traditional Mechanical Engineering course.
Supposedly more emphasis on hands on technical work and less on Analytics. Im not sure how much though. Didnt have to go any further in math than DiffEQ.
I had a buddy who was a ME for Raytheon that had to take multivariate calc, LinEA and Vector Calc. But he had a MS