cocking lift

[chet]

trying to figure out why the custom action have easy bolt lift as compared to a stock action, does anyone know approx how much the firing pin move back when cocking a custom action, i would think it would be very minimal and a less agressive ramp, and a 2 lug type would be easier to cock because of the lit travel.i am sure over cocking would be an issue on a custom action

chet

 

[Dusty Stevens]

just say you have .250 of firing pin fall. no matter what you do you have to move that firing pin back .250 so since a 3 lug action opens in less degrees than a 2 lug its going to be harder to lift. you have to do the same work over a shorter distance. a 2 lug action with a 20lb spring is doing the exact same work as another 2 lug action with a 20lb spring- some are just designed better.

 

[chet]

just say you have .250 of firing pin fall. no matter what you do you have to move that firing pin back .250 so since a 3 lug action opens in less degrees than a 2 lug its going to be harder to lift. you have to do the same work over a shorter distance. a 2 lug action with a 20lb spring is doing the exact same work as another 2 lug action with a 20lb spring- some are just designed better.

hi dusty

about 15yrs ago i modified a savage bolt body, i reduced the travel by .030 and reground the ramp to match the firing pin detent that was not as aggressive, i got a real nice bolt lift and the gun works fine. i have a feeling some of the factory guns may be over cocking. when you say .250 of fall are you saying this is the approx fall on most actions with a 20lb spring. or was that an example.

chet
ps what actions come to mind with a smooth bolt lift and less effort to lift.

 

[Dusty Stevens]

Any custom action can be smooth as silk. The pin falls i listed are for conversation only. Modifying a bolt for less aggressive ramp hurts more on pin fall than helps on cocking. The savage you list in my opinion has the worst bolt lift of any action made- factory or custom so in comparison any action you pick up should be better. I know every bat i have you can lift the bolt and close it with one finger and not disturb the crosshairs much- thats what makes a fine target action. Your gunsmith can make any custom action run like that.

 

[alinwa]

trying to figure out why the custom action have easy bolt lift as compared to a stock action,
chet

Since you really do seem to want to know......

set a 20lb cinderblock on the asphalt road and drag it....HARD... because there's poor fit and no lubricant. Grease the surfaces heavily and it "helps".... but still hard, too many pressure points.

now set a 20lb pc of surface ground granite onto a ground granite surface and it nearly floats away! (until the air's gone of course, then the two feel welded together, but I digress ) It don't even NEED no lube at first! And a coating of oil makes the two parts nearly frictionless.

The answer is surface smoothness and fit. NOT just smoothness but FITTED smoothness. Ya got's to spread the surface out so's the lube doesn't squirt around.

You can spend a few hours with a Rem 700, some Dykem and files/sandpaper and if'n yer handy you can match the surfaces to make a full broad footprint which, with a layer of lube to keep them apart will be smooth as silk.

Watch a video on "scraping the ways" of a lathe to see how the Dykem works....

 

[carlsbad]

I have replaced firing pin springs on custom actions with stiffer springs. Smooth function sells actions so many use a softer spring.

The ramp and travel is generally about the same as a rem 700 so that isn't it. 3 lug actions has shorter ramps and are thus less smooth.

Often the threads on a custom action are very smooth (you can buy upgraded shrouds for R700s and similar with super smooth threads) and the threads are well lubricated with a well chosen lubricant. This will immediately improve the feel.

I don't want to badmouth any specific brands but leaving my general statement above sounds like I'm badmouthing them all, which I am not.

Which action has impressed you with it's smoothness?

--Jerry

 

[Alex Wheeler]

My opinion from a long range Benchrest stand point is you start giving up accuracy long before you will have failure to fire issues. You need to decide if top accuracy or bolt lift is more important. Its simple to make an action open and close easy. But there are no free lunches, if you want .240"+ of pin fall and a 21lb spring like I do, it will never open as nice as an action with .215" fall and an 18lb spring. Everything being equal. Unless you like cock on close, and I dont. I have cut a lot of cocking ramps. The geometry of a ramp is critical to bolt lift just as Al stated. Guys can run 10 shots in 20 seconds with a 22lb spring and a lot of pin fall. So if your upsetting the rifle opening the bolt, your technique alone can fix that.

 

[Cigarcop]

Listen to this man ^ he definitely has figured it out

 

[Alex Wheeler]

Thanks Kieth, its a never ending learning process for anyhow. I dont think I will ever have it all figured out.

 

[WayneShaw]

An extra half inch of bolt handle length goes a long way. I always liked the longer handle a Panda has. These are bench guns, not guns carried in the field where you don't want a long handle.

 

[Ksracer]

My opinion from a long range Benchrest stand point is you start giving up accuracy long before you will have failure to fire issues. You need to decide if top accuracy or bolt lift is more important. Its simple to make an action open and close easy. But there are no free lunches, if you want .240"+ of pin fall and a 21lb spring like I do, it will never open as nice as an action with .215" fall and an 18lb spring. Everything being equal. Unless you like cock on close, and I dont. I have cut a lot of cocking ramps. The geometry of a ramp is critical to bolt lift just as Al stated. Guys can run 10 shots in 20 seconds with a 22lb spring and a lot of pin fall. So if your upsetting the rifle opening the bolt, your technique alone can fix that.

Where can a person find different springs at? (700 style) Also, how are they measured? If it takes 18# of fource to move the pin to the cocked position, is that then an 18# spring?

 

[Danny1788]

Where can a person find different springs at? (700 style) Also, how are they measured? If it takes 18# of fource to move the pin to the cocked position, is that then an 18# spring?

https://www.midwayusa.com/mainsprings-firing-pin-springs/br?cid=17511

 

[Dusty Stevens]

Wolff springs

 

[Ledd Slinger]

I will file down the cocking piece seat on top of the cocking ramp to the point where it has minimal fall from the cocking piece face to the trigger sear when closing the bolt. This gives a nice smooth closing action on the downward stroke after the handle passes over the receiver extraction cam.

Then I reduce the height of the top of the ramp going into the seat so it cams over smoothly on opening, but still securely holds the cocking piece in place. This helps reduce the amount of force required for cocking on opening.

I can time an action to open and close smooth as silk, but that requires a lot less pin fall. I'm like Alex where I like to find a good medIan point where there is plenty of pin fall coupled with smooth cycling. If you're not getting good consistent hard strikes on the primers for optimal ignition, accuracy will begin to deteriorate.

Hope my explanation makes sense...

 

[TikkaSporter]

... Everything being equal. Unless you like cock on close, and I don't...

What is it that you (and others) don't like about cock-on-close? It seems like spreading the cocking effort out between opening and closing would make for smoother bolt operation/lighter bolt lift, but I'm sure there is something I'm missing.

 

[RWO]

All commercial actions have some degree of cock on close. Rem 700 has .041" closing + .234" opening for a total of .275". Pre 64 Win Mod. 70, often said to be very smooth to operate is .104" close + .215" opening for a total of .319".

RWO

 

[Alex Wheeler]

What is it that you (and others) don't like about cock-on-close? It seems like spreading the cocking effort out between opening and closing would make for smoother bolt operation/lighter bolt lift, but I'm sure there is something I'm missing.

For bench shooting you can deal with a little bit of spring pressure on opening because you learn to roll a bolt open and the gun is usually in its recoiled position. The last thing you do before pulling the trigger is close the bolt. Rocking the gun because of cock on close is probably one of the most detrimental things you can do if your trying to shoot fast. Surprisingly to me quite a few PRS guys have had me time their actions. They complain about closing the bolt and coming off target. It all revolves around moving the rifle off target.