Originally Posted by Aussie Hunter Steve
I have owned and loaded for five 7mm RM rifles and use Federal 215M primers exclusively as these primers are designed for large capacity cases burning slow powder, some of which is hard to reliably ignite. They provide consistant ignition and loads with very little velocity deviation.
I am not suggesting this is the cause of your problem and others have given helpful advice in this regard.
I've had 3 7 rem's (not to mention a bunch of other 7mm's) and they all perform well on mag primers. A hotter standard primer like a wlr is pretty sure to ignite the powder in this case too unless you are using "ball" powders or terribly compressed with stick powder. You are only burning 10 grains more powder(give or take) over the '06 class rounds. A 7stw or 7rum (with their enhanced capacities) wiill take a 215 or equivalant.
I think the OP has got a rather simple issue like missing powder or obstructed flash-holes.
If it's not ammo(especially if it starts showing up with factories too) it is your bolt/ firing pin assmbly; gooped up or weak spring, possibly short firing pin.
If not that is may be headspace-- especially if you've been running heavy loads for a while in the rifle. It would take gunsmith work to fix that and you could tell with headspace guages. Find these either at your 'smith or order 'em in from Midway, Brownells, etc..