It’s doable. Take a look at my tutorial at the following link to see if it’s something you’re willing to tackle yourself. You need some specialized equipment to do it. Like a MAPP torch and a good padded vice.
A bunch of members just send them to me to fix. The biggest issue right now is not having a source for 3 position receiver extensions. They should return in time.
A local small time FFL or even an at home one would be best. I hold an FFL myself to facilitate transfers, mainly for gunsmithing. They'll be a lot less likely to mess with it. The hardest part is to get your FFL to link up with the person you purchased it from to get a copy of their license transferred to get shipping going. FFL to FFL transfer. Then your FFL will do the 4473 on you.
With everyone panic buying firearms, even Gunbroker is cleaned out of most of M4’s. With that, all the accessories are being cleaned out too.
In the past month, I have had more first time contacts from customers than in the past year combined.
Give it a few months and I’m sure Benelliparts and MGW will get another shipment of extensions in from Italy.