Re: FN SPR question
I suggest you familiarize yoursef with the SEARCH function for this Site and read some of the myriad posts on this EXACT topic.
I assume you have never had a custom rifle built so rather than ask an open-ended question like this, and risk having a bunch of strangers tell you what to do, what may benefit you more is to do ALOT of research, and then, after you think you know what you want to do, ask questions.
Most importantly, take your time.
IMO the FN action is fantastic and you are off to a good start.