Nathaniel G. Lambeth, Sr. Gunsmithing

ACTION TRUING

There are several levels of action truing. The first level consist of facing the action in a lathe by mounting the action on a mandrel and single point machining the face. If the action threads and bolt race are aligned facing the action and lapping the bolt lugs may be all that is require in making a rifle shoot. This can be tested by setting up the action in a truing jig and placing a tight fitting precision ground mandrel in the bolt race. Aligning the mandrel co-axially and concentrically by taking two readings from the mandrel simulatniously. Then removing the mandrel and inserting a precision turned and threaded 4." stub into the action and taking two indicator readings simultaniously one can determine the TIR (total indicated runout). The second level is if the TIR is greater than .003 then the action should be trued to a higher level. If the action has greater than. 003 and less than .008 TIR the threads can be chased by a single point lathe bit. Level three is if the action has a greater TIR than .008 the old threads should be completely removed and the action rethreaded to be aligned co-axially and concentrically with the bolt race. Level three requires a set back or new barrel due to larger tenon size. This involves a considerable amount of time, and machining expertise. It often is less expensive to start off with a custom action that is co-axially and concentrically alligned from the begining.

BOLT TRUING AND LAPPING

The bearing surfaces of a bolt action are called bolt lugs. For the best accuracy they need to have at least 60 percent bilateral contact with the opposing action lug surfaces. If these contact ponts are not making the necessarry bilateral contact they may require to be trued with a single point lathe tool and/or lapped in with lapping compound. After this service is done existing barrels may have to be set back or replace with new barrels.

BUSHING FIRING PINS

Modern day rifles are designed to operate at high pressures. If the firing pins are misaligned or loose fitting they may require to be bushed to prevent case push and primer flow. This requires the bolthead to be bored and a center drilled bushing installed.

BOLT TIMING

Bolt timing has to do with two function of the bolt, the first is cocking and the second is firing also known as lock time. This is important to smooth operation of the rifle. Bolt lift or closing is much easier if the bolt is in time with the action. Bolt timing (cocking) may require the moving of the bolt handle or replacement of the bolt. Bolt timing the firing pin may require recutting the cocking ramp, and alterations to the cocking piece an/or firing pin. This too may require the replacement of the bolt and firing pin.

TRIGGERS

Triggers on some rifles can be adjusted, but often modern factory triggers are set from the factory so as they can not be adjusted to a desired pull weight. I recomend several different aftermarket triggers. Including Jewell, Rifle Basix, Timney and several different AR triggers. A release must be signed before triggers are adjusted or replaced.

CROWNS

Muzzle crowns are an important part of a good shooting rifle. I prefer using a piloted tooling when doing crowns. After the barrel is cut with a bandsaw a piloted 60 degree cutter is used to open the edge of the bore. Then a piloted 90 degree cutter is used to face the action. Then a piloted 79 degree cutter cuts an 11 degree counter

bored crown. This gives a good protected crown.

Insert body text here ...

Insert body text here ...