yeah thars what i was thinking about northern recon has a nice ratech m4. Plus 3 of my rifles will have interchangeable mags

KAC PDWs have a short and long barrel option, my VFC PDW came with both outter barrels and inner barrel, less than 5 minutes to swap between the two.

If your looking for a gbbr I highly recommend a kjw as mine with the bolt upgrade and inner barrel is shooting almost 300 feet and is accurate to within a foot and a half at that distance. The only drawback on kjws is they are expensive to buy, upgrade, and get mags for. But in my opinion they are the best m4 gbbr