Any cure for bolt lift?

[5thBatt]

Have tried more of my rifles with the same results, i was with ed on the 'spring torque' thing but now believe the cause of "bolt lift" is the transfer of force though the receiver/bolt body repelling the bolt handle up, the spring may have some bearing on the actual "lift" but only marginally, its biggest influence would be on the outcome dependent on spring strength.

[Edward Horton]

34 years working at a Military overhaul depot overhauling aircraft, aircraft components and tactical support equipment and you think you are going to teach me something about testing and inspecting springs.
(Let alone copy anything you have ever written like an Enfield bolt vibrating like a tuning fork)

I’m not the one going to other forums asking questions and looking for answers and then pretending the answers you give in another forum are your own. Or my personal favorite you arguing with Peter Laidler the British Armourer and author and getting the post locked by the moderator for thinking you know more than a trained British Armourer.

[Edward Horton]

Have tried more of my rifles with the same results, i was with ed on the 'spring torque' thing but now believe the cause of "bolt lift" is the transfer of force though the receiver/bolt body repelling the bolt handle up, the spring may have some bearing on the actual "lift" but only marginally, its biggest influence would be on the outcome dependent on spring strength.

Over time and use the spring becomes weaker, a weak spring when compressed will become larger in diameter as it is compressed, at some point the weakened body of the spring will start to touch the inside of the bolt body and transfer even more rotational torque to lift the bolt.

Looking from the rear of the action when you close the bolt the cocking piece is being moved clockwise, when you pull the trigger the bolt moves counter clockwise.

The stored torque in the firing pin spring as it grips the inside of the bolt is doing the lifting. (and doing its lifting against gravity and the weight of the bolt, the front of the spring is anchored to the collar of the firing pin)

[5thBatt]

Over time and use the spring becomes weaker, a weak spring when compressed will become larger in diameter as it is compressed, at some point the weakened body of the spring will start to touch the inside of the bolt body and transfer even more rotational torque to lift the bolt.

Looking from the rear of the action when you close the bolt the cocking piece is being moved clockwise, when you pull the trigger the bolt moves counter clockwise.

The stored torque in the firing pin spring as it grips the inside of the bolt is doing the lifting. (and doing its lifting against gravity and the weight of the bolt, the front of the spring is anchored to the collar of the firing pin)

I agree the spring does have a bearing on the amount of "bolt lift" but its not the cause.

My 1942 Lithgow is unfired, the spring is good & strong.
When i cock the rifle & dry fire with the bolt handle down hard in full contact with the receiver, the bolt handle jumps up, but not far.
When i close the bolt with a piece of paper between the bolt handle & receiver then remove paper & dry fire, the bolt handle does not move up at all!
My MkV smle also has a good strong spring & behaves the same way.

Just tried it again, this time cocking the rifle by pulling back the cocking piece only, same result.

[Edward Horton]

The two things that effects bolt lift are how smooth the ends of the spring are and the points touching the ends of the spring, the collar on the firing pin and the inside of the bolt body, the other is the strength of the extractor spring pushing on the locking lugs.

Bolt lift is governed by how much twisting force is applied to the firing pin spring on bolt closing. (clockwise) If your bolt does not “jump” there is not enough friction to hold the ends of the spring in one position to impart a twisting torque to the spring.

It does not matter which way the spring coil is wound, as you close the bolt you are twisting the spring clockwise and loading it like a torsion bar, this twisting force unwinds counter clockwise when the trigger is pulled and the bolt rotates around the firing pin lifting the bolt handle.

Look at the photos below of the torsion bar with “no load” and "under load" and you will understand bolt lift.

It has NOTHING to do with vibrating tuning forks or WAGs (Wild A*s Guess)

Torsion bar suspension - Wikipedia, the free encyclopedia

[5thBatt]

The two things that effects bolt lift are how smooth the ends of the spring are and the points touching the ends of the spring, the collar on the firing pin and the inside of the bolt body, the other is the strength of the extractor spring pushing on the locking lugs.

Bolt lift is governed by how much twisting force is applied to the firing pin spring on bolt closing. (clockwise) If your bolt does not “jump” there is not enough friction to hold the ends of the spring in one position to impart a twisting torque to the spring.

It does not matter which way the spring coil is wound, as you close the bolt you are twisting the spring clockwise and loading it like a torsion bar, this twisting force unwinds counter clockwise when the trigger is pulled and the bolt rotates around the firing pin lifting the bolt handle.

Look at the photos below of the torsion bar with “no load” and "under load" and you will understand bolt lift.

It has NOTHING to do with vibrating tuning forks or WAGs (Wild A*s Guess)

Torsion bar suspension - Wikipedia, the free encyclopedia

Stop preaching the theory & try the practical you may learn something
The main spring is already under some compression in the fired position, when you open the bolt you apply torque then as well.
You have yet to explain why i have no or next to no "bolt lift" when there is no contact between the handle & receiver.

[Edward Horton]

Are you Alfred AKA Gunnersams brother

[5thBatt]

Are you Alfred AKA Gunnersams brother

Is that your answer to my last post!?
My answer to yours in your speak is : I know you are! but what am I?

[Jollygreenslugg]

Alfred and Ed

This petty bickering stops now.

You two fight it out elsewhere, but you won't be doing it here.

Thankyou.
Matt

[Edward Horton]

Matt

Even my dog bolt has lift