TNFrank,
If your doing a whisper in .300 and using a standard gas port/gas tube you may end up with problems on cycling. In our testing we found that the presure curve on the .300 whisper is so quick that we had to go to a 7 1/2 inch gas tube(pistol setup) system to cycle properly(JP makes an adjustable system, haven't used it though). Also order a go/no go headspace gauge and do your reloading based on that gauge. Assuming that model1sales does a good job of reaming(or who ever they had do it for them) and that your go gauge fits properly........ Otherwise
the 300/221 is a fun.... fun little cartridge. I personally like then a fixed stock, it's more repeatable and shifts/moves less the m4/CAR. Eventually look at a SIR, pof makes, IMHO one of the best ones on the market. I've had Aimpoint, Eotech, Cmore on mine, with a PVS-14(for a short period) and loved shooting at night. GG&G makes good BUIS, but I have yankee hill as well and both are great. Also, look at a tactical/oversized CH latch, tactical bolt stop and an ambidextourous selector.