Bolt faces

[Yoshi]

With respect to buying a custom action and selecting a bolt face option, can anyone tell me what the second option is trying to accomplish or what benefit it provides?

1. .473”= .308 Win. W/Remington style extractor
2. .473” W/.062” firing pin hole and Remington style extractor

 

[armed ferret]

it's a smaller-diameter firing pin hole. factory tolerances on a standard 700 can yield a larger firing pin hole that can cause minor cratering on primers. some folks get a bunch of sand in their vaginas over it, so aftermarket manufacturers offer a smaller-diameter option to avoid it. in fairness, if you're really super-anal about reloading and the thought of a minor crater could frighten and confuse you, go with the .062". otherwise, just go standard. honestly, in the big scheme of things, it don't mean shit.

 

[Yoshi]

it's a smaller-diameter firing pin hole. factory tolerances on a standard 700 can yield a larger firing pin hole that can cause minor cratering on primers. some folks get a bunch of sand in their vaginas over it, so aftermarket manufacturers offer a smaller-diameter option to avoid it. in fairness, if you're really super-anal about reloading and the thought of a minor crater could frighten and confuse you, go with the .062". otherwise, just go standard. honestly, in the big scheme of things, it don't mean shit.

The "cratering" being over-pressure issues, right?

 

[BradMacc82]

The "cratering" being over-pressure issues, right?

Not always, some primers may flow more easily than others - even under the same pressures.

 

[Deep Creek Rock]

Im not 100% what the OP means.. but some people do put a lighter firing pin, with a heavier spring in an attempt to reduce lock time. Im wondering if that is the case here.

 

[Yoshi]

After Googling a bunch of stuff, I think the the reason is that a 6.5x47 Lapua, having the .308 as the parent case, uses small primers.

 

[smokey]

Not always, some primers may flow more easily than others - even under the same pressures.

I thought the bolt face was relieved around the firing pin hole specifically TO cause cratering around the firing pin. By relieving it there, it causes the primer to flow towards the firing pin, preventing punctures.

 

[Deep Creek Rock]

Primer cratering (extrusion) is a gun problem - not usally a pressure problem. Extrusion is the ridge of metal around the firing pin indent on the primer - not the normal indentation put on a primer. It comes from excessive space/ clearence between firing pin and firing pin hole, or due to a weak firing pin spring.

A pierced primer, puts a hole clean through the primer when fired. That can come from an over sharp firing pin.

My point, reading primers are not 100% true accounts of a too high pressure of a round. If they are present with other high pressure signs, then that is a better indicator.

 

[E.Shell]

With respect to buying a custom action and selecting a bolt face option, can anyone tell me what the second option is trying to accomplish or what benefit it provides?

1. .473”= .308 Win. W/Remington style extractor
2. .473” W/.062” firing pin hole and Remington style extractor

it's a smaller-diameter firing pin hole. factory tolerances on a standard 700 can yield a larger firing pin hole that can cause minor cratering on primers. some folks get a bunch of sand in their vaginas over it, so aftermarket manufacturers offer a smaller-diameter option to avoid it. in fairness, if you're really super-anal about reloading and the thought of a minor crater could frighten and confuse you, go with the .062". otherwise, just go standard. honestly, in the big scheme of things, it don't mean shit.

Good answer. I cannot get excited about this either. The tradeoff is that if the pin is so tight it bounces down the side of the bore as it falls, we're going the wrong way for best precision.

The "cratering" being over-pressure issues, right?

Not always, some primers may flow more easily than others - even under the same pressures.

Correct. It should be monitored as potentially indicating increasing pressures though.

I thought the bolt face was relieved around the firing pin hole specifically TO cause cratering around the firing pin. By relieving it there, it causes the primer to flow towards the firing pin, preventing punctures.

This is also true, when the firing pin bore is deliberately chamfered to provide an eased edge. In a standard (traditional) design, cratering can be one of the first signs of maximum pressures. In this beveled firing pin hole, higher pressures can be achieved without "blanking" a primer cup.

When evaluating the possibility of cratering being an indicator of excess pressure, simply compare several factory loads and the appearance of their fired primers to see what near maximum, but still safe pressures look like in YOUR rifle.

 

[eddiek2000]

Good answer. I cannot get excited about this either. The tradeoff is that if the pin is so tight it bounces down the side of the bore as it falls, we're going the wrong way for best precision.Correct. It should be monitored as potentially indicating increasing pressures though.This is also true, when the firing pin bore is deliberately chamfered to provide an eased edge. In a standard (traditional) design, cratering can be one of the first signs of maximum pressures. In this beveled firing pin hole, higher pressures can be achieved without "blanking" a primer cup.

When evaluating the possibility of cratering being an indicator of excess pressure, simply compare several factory loads and the appearance of their fired primers to see what near maximum, but still safe pressures look like in YOUR rifle.

Gotta love when out resident expert speaks up!!!

Thanks Ed!!! I always appreciate your input!