GUNSMITHING SERVICES: Bushing M700 Striker Pin Hole
A relatively frequent complaint with M700 actions are cratered primers with factory standard loads. The root cause of this is from excessive clearance between the striker and the hole feature of the bolt face. When fired, the primer cup flows into the void an indicates excessive pressure.
This glitch in the design is further confirmed when inspecting the radius transition around the circumference of the primer. If it has not been hammered flat, it's unlikely that the ammunition is exceeding pressure limits. Additional confirmation of this can be observed from the absence of an ejector mark/swipe on the face of the brass and case webs that have not grown excessively*.
*a "tick" at the top of the bolt's rotation out of battery is a tell tale sign of case web growth due to excessive pressure.
Machining the bolt and installing a bushing around the striker pin to tighten the tolerance is the answer to solving the issue.
Our bushing installation process is performed using a Hardinge HLV Ultra Precision Tool Room Lathe. These are highly sought after machines for precision manual lathe work. We install a heat treated insert into the bolt that is then drilled and faced square to the bore.
It is important to note that part of this procedure involves a cleanup pass on the face of the bolt. This will alter the headspace dimension of the rifle slightly. It's impossible to know exactly how much because factory bolts do have some variance.
Because of this, it is best to have this service performed in conjunction with our accurizing service PRIOR to installing a new barrel.
The striker is then turned down from .075" to .0625" resulting in a smaller impact crater on the primer. Striker protrusion from the bolt face is also inspected and set to run within a tolerance range of .055" +0/-.003".
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