Re: Rem 700 vs Wby MkV in bolt locking lug comparisions....
I machine my receivers and barrel for 5 thou diameter clearance(total, 2.5 thou each side) and 5 thou end clearance. This is about as tight a fit as I recommend machining.
A bench gun used only in clean conditions may allow a slightly tighter fit but I have not seen any advantage in accuracy to doing so.
The idea is to control the case head as solidly as possible. The reason is once a leak occurs in the case head, be it in the primer pocket area or web area, if it is allowed to vent freely it will act like a cutting torch and cut the bolt, barrel and receiver apart.
WIth a bolt fitted correctly, there is room for some gas to escape but the vast majority is directed down the firing pin hole and then out the vent hole in the bolt head. This vent hole is positioned so that it vents the gas into the locking lug recess area and out the vent hole in the receiver. This is why a Rem fitted with a sako extractor generally has the extractor blown out in the case of several case failure. If you are shooting the corret handed rifle for you this is generally not an issue as far as injury but if you are shooting a right hand rifle in the left hadn position, never do so with a rifle fitted with a sako extractor.
Point is if your left hand get a left hand rifle as the rifles are designed to protect a shooter that is supposed to be using them. Right hand use a right hand rifle, left, use a left hand rifle.
Anyway, back to the Rem 700. The idea is to contain the case head securely as possible to prevent the case head failure. The primer will let go far before the case head will if you are using modern, quality brass which we all better be using. The Rem 700 is designed to use the bolt head and barrel as a case head vice and then allow any venting gas to be released out of the firing pin hole and out the side of the bolt body.
Primary function of the Rem 700 bolt head and barrel bolt head recess is case head control and support.
As far as factory rifles, I have found them to be as tight as 0.007" in bolt nose clearance and as loose at 0.025" in clearance.
In end clearance, I have found a range of about the same 0.010" to 0.030". Certainly not as tight as a custom fitted receiver.
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