Cratered Primers-Bushing Fireingpin hole?

[reloader243]

How much is cratering a problem? If all other measures of pressure are not present, how much cratering of the primer is acceptable ? And if it is never acceptable..how does one get rid of it? I see cratering with my Savage target action with the factory .308 barrel. No heavy loads,42-43 gr Varget,168gr Sierra match.. in the .308 no pressure signs with primer flatening or case bulge...etc..I rechecked the headspace with Go,No-Go guages..Fed 210 and 215 primers.Rem primers..all seem about the same. Never a miss-fire and no "holed" primers. It even shows with my 111 action when fire-forming .243 to .243Ack..factory hunting loads for Win & Federal..Guide me in the right direction..

 

[AlNyhus]

Reducing the clearance between the pin tip and the hole in the bolt head will help with the cratering. This 'crater' is actually metal from the primer that flows between the pin tip and the hole as the primer cup flows against the bolt face during firing. The outer edge of these 'craters',the parting line) is where the primer cups may be sheared,also called 'blanking'). These pieces of the primer cup will end up behind the bolt face and can eventually impede the foward movement of the pin assy.

In a bolt with a solid head,like Rem. 700's), you can run as little as .0005-.001 clearance. The basic Savage design,swiveling bolt head) limits the effectiveness of this approach as reducing the clearance to this amount can cause the pin tip to drag excessively and bind as it moves through the hole.

It's still worthwhile to eliminate as much of this cratering as possible, though. -Al