Bolt handle jump

[dminn1]

I have a Rem 700 .308 that has a noticeable rotation of the bolt handle upward when you drop the firing pin on an empty chamber. This is most pronounced when the handle is fully closed and resting on the action. If you rotate the handle up very slightly before releasing the firing pin the upward movement is much less. I imagine this is a timing issue and was looking for some help on how to address this issue, or if it even needs to be addressed.

Thanks
Darin

 

[FatBoy]

Does it do it with a snap cap or fired case?

 

[dminn1]

Does it do it with a snap cap or fired case?

When I use a fired case there is no detectable movement.

 

[FatBoy]

That sounds normal to me.

 

[dminn1]

Thanks for the drawing. So If cocking piece/ cocking ramp interference is taking place it could/ would affect ignition and consequently accuracy?

 

[Ggmac]

Remington 700 have an angled sear , which when cocked , pushes the rear of the bolt up against the roof of the action . When you pull the trigger everything drops as Alex's drawing shows . A good article to read is called JUST RELAX by Bill Calfee
To answer your last question , yes it COULD. But you'll never see the difference. It's all in his , Calfee research .

 

[Alex Wheeler]

Thanks for the drawing. So If cocking piece/ cocking ramp interference is taking place it could/ would affect ignition and consequently accuracy?

If the cp is hitting the bolt on its way down, this would be a major accuracy killer.

 

[DaveTooley]

I agree with what all my colleagues have said and I'll add one thing. One other contributing factor. Your bolt shroud is loaded on the right side from the simple act of closing the bolt. It also acts as a pivot point on the handle.

 

[X Ring Accuracy]

True story.......Had an acquaintance that hit pawn shops regularly looking for a great deal on a 700. He would dry fire it at the pawn shop. If the handle jumped, he would talk them down to pennies on the dollar.......Then, then....then NOT buy it, I would get his report of pricing and head to the pawn for a smoking deal. We weren't trying to beat the pawn shops, he was a shop rat that came by my shop to profess his "scrutiny" of available guns. Bolt handle jump is normal on an empty chamber. Some more than others for reasons as has been stated. Worst case is a new firing pin / shroud and an aftermarket trigger to seal the deal.

 

[mikecr]

With many actions I see that there are bolt turned positions leading to rise, no movement, or fall of bolt handle on firing(makes no difference if dry or live firing).
I once fixed this with a Savage action using ball detented bolt turn. With this, handle turn always clicked into a position that tested neutral on dry firing. The cocking piece was clear of tang slot friction and spring loading of the ball preloaded the bolt lugs back against action abutments, so the bolt did not move forward/rearward on firing either.
Finally, I installed pin indexing of the shroud to the back of the receiver, with bolt turn in detent, to ensure clean cocking piece fall in the shroud.
With that action(Savage) I did not see bolt lifting with sear engagement, but I'm sure an action could be modified to prevent this. A rear 'Borden bump' maybe. A trigger hanger adjustment.

I don't have that action anymore. It's locked up in some Canadian border warehouse..
But I always wondered why action makers don't address clean pin fall. IMO, that bolt, or it's shroud, should not move one bit on firing.
After all, any energy going this route would surely be removed from striking energy, and how consistent would that really be?

 

[BoydAllen]

If the CP hitting the bolt is making the handle jump, and raising it slightly solves the problem, it is very likely that the CP is striking the bottom of the cocking cam notch on the side of the radius opposite the cam. It is also likely that the pin does not fall far enough for this to happen during live fire, because the primer stops its forward motion rather than the shoulder of the pin.

 

[Mozella]

You ain't kidding! What exactly were you attempting to draw?

If this weren't a gun forum, I would say the drawing is Not Safe For Work.

 

[rangertim]

Alex your drawing makes a perfect illustration ! And Gunsmith's like you know what it takes to time bolts and all the interworking's on firing pins, shrouds and cocking pice and Trigger placement and the accuracy difference it makes when it's Right ! Jim Borden has it perfected on his actions.

 

[mikecr]

That's what I'm talking about! Zero bolt movement on firing.

 

[Paul Seaman]

You ain't kidding! What exactly were you attempting to draw?

I'm a welder that's a lot better drawing than most of the scrawl I get most times. Prints what prints crayon on Toilet paper is good enough! I'll give him credit it looks like a bolt handle to me!

 

[rayjay]

Do things that happen when pulling the trigger on an empty chamber have any bearing at all on actually firing the gun ? When dry firing the firing pin slams violently into the bolt body. When firing the firing pin is comparatively gently brought to a standstill well short of contacting the bolt body. There is also the aspect of having a cartridge in the chamber that precludes the bolt from moving forward more than a few thou.

All sorts of monkey motion can occur when dry firing that can't occur when actually firing.

 

[mikecr]

Well, you can test for yourself firing primed only cases.

 

[Kevin Taylor]

If this weren't a gun forum, I would say the drawing is Not Safe For Work.

Yes, I was thinking I knew her.......

 

[lloydx2]

We are lucky to have people out there that are willing to share good information
with us. Thanks Alex.