You've got two approaches to fixing safety wobble:

1. Take a consistent-diameter dowel and fashion your own detent; or

2. Reprint and step-down the detent hole with multiple bits. You want to run a smaller-diameter bit through it that corresponds to the smaller diameter of the detent, then a larger one just deep enough to let the detent present to the cam properly without overextension. I forget which bits you need, but they're common imperial sizes

There are one or two remixes for the SF5, but no major forks of it. Can try a monolithic lower or tapered handguard if you'd like.

I made a new lower that is grip integrated, but I won't be uploading it soon due to it being poly modeled. One thing I noticed about the safety detent is that the hole is either misaligned on accident or purposely.

Many times when drilling the detent hole do I accidentally bust a hole on the side wall making the detent not so snappy