Action Timing for Hunting Rifle

[Mram10us]

Maybe Wheeler can explain it in better terms to you. Take an old cocking piece from a rem 700 and grind 1/16 inch off the bottom of the cocking piece engagement. You will notice the action closes much easier. But your accuracy will be poor because of inconsistent ignition because your pin fall is reduced by the amount you ground off. Most actions need at least .225 to .250 of pin fall to shoot right. To get a Remington timed right with just the cocking piece will put the pin fall around .200 or less. They feel great but shoot like crap.
shep

you're playing chess again, buddy. I am ignorant to that so I'll study up

 

[FEENIX]

I'd ask what each of those means and feels like. That's part of what you are paying him for right?

Agreed!

This is on an older action model, but it gives a general idea, and I thought the young man did an excellent job explaining ...

 

[Deleted member 103481]

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[nksmfamjp]

Let's see if I can simplify. There is a certain amount of "firing pin fall" (distance from cocked to fired) that a rifle needs for ignition and I hear accuracy.

The way a firing pin gets from fired to cocked is by opening the action against the cocking cam on the bolt and pushing closed against the trigger sear.

The cocking cam force is about 80% of your force to open your bolt. You can slick this up, polish it, whatever, but it still will have pretty high force. If you time a rifle to have some cock on close, you can reduce the cocking force by changing the ramp....not sure if your smith intends to do that.

Cock on close will finish the cocking, but it will add force to the bolt stroke right before rotating it to lock the lugs. Running the bolt fast, you likely won't notice. If you are running a BR type rifle, you are trading open force for close force. As you heard here, most prefer no close force off the bench.

On a hunting rifle, I prefer a bit of cock on close and a polished cocking ramp for smooth cock on open because I'm running the action fast with little thought other than overall smoothness.....hmm I forgot to discuss with my gunsmith on my current rifle build, but i sent a model 70 action that was well timed by my opinion.

 

[Alex Wheeler]

I assume the action is a Borden. The difference is, do you prefer a smooth closing cycle or a lighter bolt lift? To achieve a neutral hand off/no cock on close the cocking ramp must be steeper which causes a slight increase in bolt lift. That is, if the action is design correctly, which a Borden is. Some actions will eliminate cock on close and keep a shallow ramp. You end up with short firing pin fall (loss of accuracy) or really short closing cams (smooth cycling suffers). Personally I can not stand cock on close and simply will not own an action that has it. Its my own personal opinion that cock on close is an unfinished product from a gunsmith, who is ultimately responsible for the finished product.

 

[anwahs]

I assume the action is a Borden. The difference is, do you prefer a smooth closing cycle or a lighter bolt lift? To achieve a neutral hand off/no cock on close the cocking ramp must be steeper which causes a slight increase in bolt lift. That is, if the action is design correctly, which a Borden is. Some actions will eliminate cock on close and keep a shallow ramp. You end up with short firing pin fall (loss of accuracy) or really short closing cams (smooth cycling suffers). Personally I can not stand cock on close and simply will not own an action that has it. Its my own personal opinion that cock on close is an unfinished product from a gunsmith, who is ultimately responsible for the finished product.

Thanks Alex, your assumption is correct and appreciate your explanation.

 

[Canadian Bushman]

I prefer a little cock on close.

I open my actions quickly with the 2nd knuckle of my index finger and i usually slam the bolt handle down so i move right through the last bit of the cocking.

 

[Ozzy MN]

I prefer cocking on opening as stated byAlex.