Springfield will sell you RSA, as for parts, some do need slight fitting, not all are drop in like on a Glock, on any revolver, all needs fitting, and you need the proper tools for some of these not many invest in gunsmith tools, files, stones and such, just saying.Said no guy ever.
We’re fixers by nature.
Them not wanting “ qualified individuals” working on Their products is a Cheap excuse.
Springs and others smalls can be handled by the owner. As a firearms owner you should be capable of changing out certain things as they wear.
If you own an AR I would hope you’re already doing some of this.
Maybe my expectations are to high… but I still change my own oil.