Why does the bolt on a

Hunter

Hunter

Runnin' Along
dedicated benchrest rifle seem to open and close so easily compared to the stiffness of a factory rifle?
 
Timing of the primary extraction and the cocking piece to trigger is a lot of it. Closer tolerances and finish don't hurt either.--Mike Ezell
 
Mike, thanks for the reply, but I still don't understand. :) How does "timing" and/or "closer tolerances" affect stiffness? Can you (or anyone else) add some clarity?
 
I'm not sure what you're asking if not about how easily they open and close. Search here for bolt timing. There are pages and pages describing what it is in detail. If that doesn't help, maybe someone else can. --Mike
 
My son has a late model Rem 700 that is pretty stiff, it has 23 pounds of firing spring pressure. That, combined with the rather rough cocking scroll in the bolt, and rough cam areas, all contribute. The biggest culprit is the cocking scroll at the back of the bolt. Most are not very smooth.

On my old 721 project, I polished all of the surfaces, lapped the cocking ramps on the action abutments, and it is pretty darned smooth cocking and extracting, even with 21+ pounds of spring.......jackie
 
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I have a CG Millenium rifle that I use for Palma and Fullbore shooting. The bolt has four lugs and bellville washers in the bolt propel the firing pin. The short throw of the four lug design and the washers make for substantial bolt lift. I have to place my thumb on the tang to get sufficient leverage to lift the bolt and cock the piece. My first experience with BR rifles was quite an eye opener when it came to bolt operation. However I still have some issues with the bolt "click" that I haven't resolved yet.
 
jackie schmidt said:
My son has a late model Rem 700 that is pretty stiff, it has 23 pounds of firing spring pressure. That, combined with the rather rough cocking scroll in the bolt, and rough cam areas, all contribute. The biggest culprit is the cocking scroll at the back of the bolt. Most are not very smooth.

On my old 721 project, I polished all of the surfaces, lapped the cocking ramps on the action abutments, and it is pretty darned smooth cocking and extracting, even with 21+ pounds of spring.......jackie
Click to expand...

Good points!
 
Most BR actions have a long smooth bolt handle and this helps a factory action a lot. Polishing the cocking piece and the cocking ramp is important. I also remove the 'detent' at the full cock notch. Removing the detent allows you to reprofile the cocking ramp further reducing the bolt lift.

Some combinations of receiver/bolt/trigger have a timing issue where they end up with way more firing pin fall than is needed. This can make the bolt require more effort to close as you are compressing the firing pin spring as the bolt is closing. My 40X had this problem and fixing it made the gun much more enjoyable to shoot.
 
Jerry, regardless of the propaganda put out by proponents of three and four lug actions, the laws of physics have not been repealed. It is a fact that it takes a certain amount of firing pin fall and spring weight to achieve consistant ignition. When you shorten the amount of bolt travel, but still maintain the amount of distance that the cocking mechanism must travel, then the amount of bolt lift will be more difficult. It is a simple fact of mechanical advantage.

Most actions are designed with the correct amount of primary extraction. If not, what you are left with is having to pull back on the bolt handle and "yank' the case out at the top of the cycle.. There is at least one major action on the market that when first brought out, did NOT have enough. They had a recall, so to speak, and fixed the problem on all subsequent actions.

I'm not sure that has anything to do with the "click" at the top of the cycle. That sounds more like brass that has seen better days, not enough sizing at the web, too tight of a chamber at the web, too hot of a load, or a combination these..........jackie
 
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