Looking for some sort of mid/long range shooting event for where the following would be legal:
5.56 14.5-16” bbl, flash hider, 9” FF tube, middy gas, adj gas block, fixed side charging upper (bear creek), custom/non milspec carrier, custom buffer & action spring, vari power scope up to 8 or 9x, maybe a nice trigger...

Looking to either run an AR like that or a similar non-ar rifle.

ETA: looks like PRS gas gun tactical light would fit the bill, so long as you dont HAVE to do that with exactly an A15??

Thank you.

You can run any semi-automatic so long as it’s chambered in 5.56/.223 and you’re not shooting anything heavier than 77gr and no faster than 3,000fps.  
The reality is that there are no other rifles out there that can compete with the AR in terms of accuracy.  MDR, Tavor, AUG, FNAR, Bren, even the FN SCAR.  None of them have the inherent accuracy capabilities that you can get with an AR with a heavy match barrel and free-float handguard.  If you use anything besides an AR, you’re going to have a very difficult time remaining competitive.  There aren’t very many gas gun matches these days, but when they have them, there’s a mess of JPs and high-dollar Franken-ARs competing with barrels that are punching sub-0.5moa groups.