Dismantle the misfires. Use a bullet puller. It may sound obvious, but check there is powder in them. If not, there's your problem. If there is powder, check whether the primer fired. If it fired, then either something is wrong with your primers or powder. Test the powder, tip some onto the concrete and put a match to it. It should burn vigorously. Does the powder smell OK? If it is acrid, then its 'off'. Chuck it on the lawn. If the primers didn't fire then maybe your cases are too short (in terms of headspace). If so, try some new brass without full length resizing. If you can, measure the headspace of your brass. Try neck resizing only. If that's all fine, look at you firing pin: is it the correct length; does the tip look intact or damaged: are you getting the correct protrusion from the firing pin tunnel; is the bolt clean internally; does the spring appear stong enough?
It's highly unlikely to be defective primers, presuming you store them in a cool dry place. The failure rate for primers is less than one in a million (according to Federal) so perhaps you would experience one but not successive failures. And there's nothing wrong with Remington primers, or CCI, or Federal, or PPU for that matter. Well, the latter are a bit tight in some brass but they delivery superb accuracy. No, your problem lies either with your brass or your rifle. If the headspace is too short, then the firing pin is losing energy pushing the case to the front of the chamber and hence has less energy to detonate the primer.
-JMS
