What length Nesika action are you using for your 6.5/284? Is it a repeater? If so what kind of magazine are you using and what are the overall lengths of your cartridges? It seems like no one makes an action that is optimum for 6.5/284 type cartridges that are loaded with heavier for caliber bullets. As I see it, if you use a short action you have the following choices:
Seat heavy bullets (142 grain) much deeper than optimum so it will feed
Use as a single shot
Peform a fair amount of machining and use a specialty magazine to make it work.
The only other alternative is to use a standard length receiver which defeats one of the purposes for using a short case. It would be nice if someone made an action that was purpose designed around "intermediate" length cartridges. This action could be used with other rounds too, e.g., 300 WSM
loaded with heavy bullets. Just curious as to which way you went on this and why.