Thread: Any cure for bolt lift?
Retrieved: 06/03/2014
The fairly common tendency for an Enfield bolt handle to lift a few degrees when the striker goes forwards whether dry firing or with a round chambered.
Of three Enfields only my 1915 No.1 exhibits any noticable lift.
It has the original numbered bolt body.
My No.4 and a Lithgow 1944 both have new condition replacement bolts on worn receivers and neither exhibits any noticable lift when fired.
Is there a explanation for why this takes place, and is there a fix that doesn't require a new bolt body?
The 1915 has good head clearance and bolthead over travel is with prescribed limits.
The locking surfaces show equal bearing.
The track of the guide rib does seem to be a hair wider at the rear than at the charger bridge.
There does not appear to be any sloppiness to the fit of bolt body to receiver.
Thunderbox
05-08-2009
It is completely normal on all Lee Enfields and does not require any fixing. The only thing actually preventing bolt lift is friction within the bolt channel - which is why older SMLEs tend to show most bolt lift, and late No4s show the least.
The cocking piece has a safety lug that prevents the bolt from opening during the firing process - if the bolt is slightly open, then this lug cams the bolt closed. If the bolt is somehow half open, the safety lug prevents the cocking piece from going forward.
Alfred
05-08-2009
This was helpful. Rather than inducing "friction" I gave it some thought and decided that "resistance" would be better than friction, so I looked about for some thick grease but found an old can of paste wax first. I applied a coat of paste wax to the bolt head threads, the bolt body, and inside of the receiver and let it dry.
This reduced the amount of lift noticably, but it remained to an extent that I figure couldn't be good for the locking surfaces of bolt or receiver. Too much lift and it reduces the area of engagement.
I then noticed that if I did not allow the root of the bolt handle to contact the action strap the vibration that apparently causes the bolt handle to bounce away from the strap didn't occur and there was no bolt handle lift.
I then thought back to when I installed the replacement bolt bodies on the No.4 and the Lithgow actions which don't exhibit any tendency to lift.
Not having had much experiance with Enfields at the time I assumed that the root should conform in shape to the curvature of the strap and required hand fitting. I used a half round jewelers file to bring the two curvatures to a close fit with the guide rib making contact with the flat of the receiver opening.
The root of the 1915 bolt handle had left a slight indentation from contact with the strap over the years.
I decided to go for broke and filed the underside of the root as I'd done with the No.4 and the Lithgow.
The result is that there is a barely perceptable lift when dry firing, so little that you'd have to look very closely to see it at all.
I would not have considered altering the bolt handle, even on the underside where no eye can see it, except that the amount of bolt handle bounce and lift was frankly alarming, and getting on my nerves.
It was reducing the amount of engagement by more than 1/3.
I did a smooth even job and removed the absolute minimum of material.
This might not be a cure all but it seems to have worked in this case.
Had it not I'd have been ordering a replacement bolt body by now.
A rifle with less descernable lift might be served by just using a thick grease or dry lube /waxy coating on the bolt body.
PS: The "Mud of Flanders" probably served the same purpose.
We often forget that these rifles were not designed to benefit from the relatively thin gun oils and CLP of today.
Amatikulu
05-08-2009
Thunderbox has said it all regarding the safety aspects of bolt lift.
I had a Lithgow that used to lift noticeably and on thinking about what takes place during firing, I concluded rightly or wrongly that the bolt handle must be lifting before actual ignition of the round - I'd need a high speed camera to confirm that Why I believe this is due to the forces involved the case would be moving rearward during ignition closing any gap between the bearing surfaces of the bolt, making them less likely to rotate.
On that basis, I decided that the striker spring must have been weak and that during the movement of the striker going forward, and the rotation imparted by a spring, that the bolt was lifting. I replaced the spring with a new one and the bolt lift was reduced to being negligible.
Alfred
05-08-2009
I figure there are several factors working at the same time, to a greater or lesser degree depending on the individual rifle.
Before I obtained a new condition bolt body for my No.4 I'd found the old striker spring was badly rusted. The only spring of the general type I could find was identical to the Enfield spring except wound in the oposite direction.
When I installed that spring bolt lift was reduced by more than two thirds.
When I installed the new bolt body with the same spring and a tight fitting No.3 bolthead Bolt lift was entirely eliminated though theres far more play between bolt body and receiver than with my 1915 No.1.
On an off chance I checked the threads of the bolthead of the 1915.
There's little overturn to the bolthead but there was slight but noticable sideplay.
The threads in the bolt body look okay, but the threads of the bolthead seemed to be worn more at the front than at the rear.
As a test I wound a couple of turns of the superthin Teflon tape used to seal plumbing joints around the bolt head threads at the front end.
The BH then screwed in snugly.
Now there is no bolt lift at all.
Since the Teflon tape will take no firing stresses and act merely as a solid lubricant I'll leave it there for now.
I guess I'll start planning on getting a new condition bolt head fitted as soon as possible, preferably one a tad longer to tighten head clearance enough for longer case life.
The rifle has pretty close headspace as is, and has never had annular rings in its fired casings.
Edward Horton
05-08-2009
When the firing pin spring is compressed it stores torque or rotational force which tries to lift the bolt handle, if the ends of the firing pin spring has any burs or rough edges the ends of the spring can dig into the bolt body and the collar on the firing pin increasing bolt lift.
After the trigger is pulled the extractor spring is the only thing pushing and holding the locking lugs of the bolt into the lug recesses of the receiver and a weak extractor spring also increases bolt lift.
Bolt lift does not occur when a live round is fired because the chamber pressure is pushing the bolt to the rear and holding it in position.
The two most used and abused springs on the Enfield are the extractor and firing pin spring, I replace both with new springs, you do not know how long the rifle was stored with the bolt closed and possibly cocked thus weakening both springs.
Heavy grease, Teflon tape or any other shade tree fix is not the answer to bolt lift or is it required. Stoning any burrs or rough edges on the ends of a NEW firing pin spring and a NEW extractor spring is all that is needed.
Alfred
05-08-2009
Bolt lift does not occur when a live round is fired because the chamber pressure is pushing the bolt to the rear and holding it in position.
I've seen bolts lift even when firing a live round.
If you mean that the pressure of the fired round does not contribute to bolt lift I'd agree that it most likely does not.
The two most used and abused springs on the Enfield are the extractor and firing pin spring, I replace both with new springs, you do not know how long the rifle was stored with the bolt closed and possibly cocked thus weakening both springs.
Both springs are in excellent condition, the striker spring snapper than
almost any other I've seen.
Heavy grease, Teflon tape or any other shade tree fix is not the answer to bolt lift or is it required. Stoning any burs or rough edges on the ends of a NEW firing pin spring and a NEW extractor spring is all that is needed.
I'd thought so as well, but I stoned and polished the ends of the spring long
ago.
Torque is one of several factors, not the only one. If it were the bolt would have continued to lift to the same extent when the bolt handle root was not in contact with the action strap, it did not.
The Teflon tape is not a fix, it was intended to confirm that a snug fitting bolt head helped alieviate the problem, in large part by allowing the extractor spring to put its full strength to work.
The bolthead will need to be replaced, but I'll leave the tape where it is for now, it harms nothing and takes no pressure, it serves only to keep the bolthead and bolt body in alignment. The front of the bolt body opening and the shoulder of the bolthead take all the pressure at that point.
There was no sign of the loose bolthead causing any problem with pressure so the effectively shimmed BH shank will cause no complications, the teflon acting as a dry lube layer and ultra thin shim.
If I had a Texas Platers outfit I'd have a go at aplying a thick plating of nickel to those undersized threads.
A new bolthead is the more permanent "fix" for that element of the problem.
The worn or somehow undersized threads just behind the bolt head shoulder allowed the bolt head to shift just an RCH to the right under the pressure of the extractor spring, not enough to be easily visible but enough to take away a bit of the springs influence.
I agree with Amatiklu that I concluded rightly or wrongly that the bolt handle must be lifting before actual ignition of the round -
In this case at least the upward rotation of the bolt handle would occur an milisecond before ignition, otherwise the chamber pressure would prevent movement.
In this particular case of bolt lift it appears than the metal of the bolt body acts like a tuning fork. The vibration channeled from the bolt body to the handle root resonated in the right pitch to turn vibration into mechanical force. The contact point caused the bolt root to bounce in a manner of speaking, be repelled might be a better description.
I think we've all seen metal objects dancing across a table and windows shaking from sound vibrations alone.
Striker spring torque alone was not enough to raise the handle, since the spring ends are polished slick, but what there was of it relieved the handle of most of its inertia allowing the relatively weak force of the vibration to do the rest.
There are several factors that can result in the bolt handle kicking up. Spring torque was one I'd already thought of long before and dealt with. It was not sufficient on its own and the polishing of the spring ends was not a sufficient fix on its own.
I may look for another reverse wound spring for the firing pin. Thats should help the situation as I already know that it helped the similar situation of the No.4 before I replaced the bolt body and bolt head of that rifle.
Edward Horton
05-08-2009
First you tell us inertia holds the bolt head in position and the magazine holds the bolt in position and now you want to tell us the bolt is acting like a tuning fork and vibrating upward against the force of gravity.
You have a lot to learn about springs and what is really causing the bolt to move upward but I can assure you the bolt is NOT vibrating like a tuning fork and moving upward against gravity.
Maybe you should go to some other forums and ask them why the bolt moves upward AGAINST the forces of gravity, go ahead and ask in other forums, you learned a lot about double base powders by asking other people.
Bolt lift is not rocket science.
5thBatt
05-08-2009
Got out my 1907 BSA MkIII, 1916 Lithgow MkIII & 1942 Lithgow in mint condition, dry fired them a few times each with the bolt handle hard down on the receiver & then with the bolt handle just clear, the "bolt lift" was clearly reduced on the early rifles & eliminated on the 42 Lithgow.
5thBatt
05-08-2009
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
05-08-2009
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
05-08-2009
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
05-09-2009
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.
5thBatt
05-09-2009
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.
Alfred
05-09-2009
After your experiment I started thinking on ways to preven contact without making any other alterations but haven't come up with a viable idea as of yet.
A simple piece of cloth tape under the bolt root might do the trick.
I've found there's a very much reduced upwards bounce from the guide rib contacting the flat of the receiver opening, not much but a hair.
The resistence of the Teflon wrapping on the bolthead threads overcomes that easily enough, and a more snugly fitted bolthead would be the final answer for my rifle.
If there had been significant over rotation of the bolt head I'd have noticed how loose it was at the front more easily.
Your rifles seem to be in pretty good condition, with simply inducing clearance being enough to prevent bounce from vibration.
If you can find a very thin material that won't transfer vibration, one not so thick as to prevent proper locking of the bolt, we might find a simple non invasive fix.
I'll check to see if the reverse wound spring I used on my No.4 will fit the No.1.
Edward Horton
05-09-2009
If it ain't broke don't fix it.
There are no repair instructions in any Enfield manual I know of for bolt lift.
When you dry fire the Enfield rifle you have the weight and mass of the cocking piece and the firing pin striking the rear of the bolt head, this along with the firing pin spring causes the bolt to lift.
When you fire a live round the firing pin strikes the primer, the blow is softened and the chamber pressure of 46,000 CUP holds the locking lugs in place preventing upward movement of the bolt.
We don't need to reinvent the wheel or fix something that isn't broke.
5thBatt
05-09-2009
Personally i am not trying to fix the 'problem' of "bolt lift"
The strength of the spring seems to control the amount of lift, the weaker the spring, higher the lift.
If this is so, when someone posts they have excessive bolt lift when they dry- firing, then a reply that they may have a weak main spring is more productive than just saying "don't worry they all do that"
Edward Horton
05-09-2009
If you store your rifle with the bolt closed you are putting the extractor spring under load and over time this will weaken this spring. (more bolt jump)
If the firing spring becomes weak you can have more bolt jump.
If the firing pin is not adjusted properly you could have more bolt jump.
If the *bolt head timing is not set properly you can have more bolt jump.
(*When the bolt head contacts the collar on the firing pin as you screw the bolt head closed.)
How well used and polished the bolt lugs and bolt lug recesses are can affect bolt jump.
(Are they slicker than snot on a door knob) What type super slick oil did you oil your bolt with?
The list goes on, headspace, bolt head over rotation, numerous worn parts, the phase of the moon and a spastic trigger finger could effect bolt jump.
Many things can effect bolt jump, the secret to bolt jump is to properly maintain your Enfield rifle to the standards in the manuals and then don’t worry about it any more.
I will say this one more time, the two most used and abused springs on the Enfield rifle are the extractor spring and firing pin spring. I have tested thousands of aircraft hydraulic pump springs during pump overhauls and on the Enfield rifle when it comes to these two springs “when in doubt, throw them out” I replace these springs on my shooter Enfield’s with new ones.
Know thy rifle, and don't listen to wild rumors.
5thBatt
05-10-2009
I hear what you are saying Ed but the main cause seems to be the shock of impact from metal on metal causing the bolt handle to "lift" jump would be a better word.
I may be wrong, but you are not making any attempt to explain why the "lift" is largely reduced on all & eliminated on some rifles when the contact between the handle & receiver is eliminated.
Alfred
05-10-2009
Originally Posted by 5thBatt
Also reread Alfred's next post about seeing "bolt lift" with live firing, i
have also witnessed this, could this be due to a excessively weak spring
causing the firing pin and cocking piece to bounce or maybe a firing pin to
set to far back causing the cocking piece to slam into the rear of the bolt
body?
There's a possibility that sluggish ignition contributes, allowing the bolt
handle to rise further before the chamber pressure comes into play.
If so then there might be less bolt lift when fresh ammunition is used.
If the *bolt head timing is not set properly you can have more bolt jump.
(*When the bolt head contacts the collar on the firing pin as you screw the
bolt head closed.)
Thats something I'll check on.
The way the shank of the bolt head of this rifle is visibly broader at the base than further up towards the shoulder might be the result of repeated impacts upsetting the metal. The bolthead is more worn than it appeared to be because it still clocks in within prescribed limits due to the base being hammered by the firing pin collar. Its possible that the previous owner did a lot of dry firing practice, or if the rifle spent some time as a training rifle it may have been dry fired much more than fired with live ammo, which would go a long way towards explaining the still excellent condition of the bore.
Excessive bolt jump may be a result of excessive dry firing.
Some slight bolt jump is tolerable and nothing would be thought of it, so no real fix was required, rifles still in service would be unlikely to be dry fired much if any. The replacement of weak springs and such as a matter of course would be enough.
Old rifles that have been out of service for a generation will have received no attention from armorers for several decades. Those given to third world allies or WW2 resistence groups may have never received any attention from an armorer trained in inspecting and repairing Enfields.
Edward Horton
05-10-2009
You are right I have not answered "why the lift is largely reduced on all & eliminated on some rifles when the contact between the handle & receiver is eliminated."
Now I will tell you "why" I didn't answer your question, the Enfield bolt has two positions when cycling the bolt "Fully Opened" and "Fully Closed", the bolt does NOT have a partially closed position, a almost closed position or a almost partially closed on a piece of paper position.
If you want a real answer to your question there is no such thing as bolt jump, but some Enfields have had the Snoxall speed cocking modification done to them.
Alfred
05-10-2009
Originally Posted by Thunderbox
The cocking piece has a safety lug that prevents the bolt from opening
during the firing process - if the bolt is slightly open, then this lug cams
the bolt closed. If the bolt is somehow half open, the safety lug prevents the
cocking piece from going forward.
The lug of the cocking piece in its track allows the bolt to rotate nearly
halfway out of battery, that greatly decreases the strength of the lock up.
Theres not such a great margin of safety in the Enfield or any other bolt
action that this would be acceptable. It would continually batter the locking
surfaces at the midway point damaging them sooner or later.
A "friction" fit of the bolt or heavy treacly grease to induce resistence doesn't address any causation, it just masks the situation.
Never seen a bolt designed to bind in its track.
5th Battery at least had the courtesy to examine the question and perform a simple test on his three rifles of various vintages.
5thBatt
05-11-2009
Ok, I just took apart the bolt on the 1916 Lithgow that has a high bolt lift when dry firing, when re-installing the firing pin I would have applied a small amount of torque to the spring that would force the bolt down, I inserted the bolt while holding the trigger down & then closed the bolt down, this of cause will apply torque opposite to the installing the firing pin but as there has been no change in the pressure on the spring they would most likely count each other out, I then pulled back the cocking piece back only, no cycling of the bolt & dry fired a few times while holding the handle down to undo any torque there maybe left in the spring, I then proceded to test dry firing as earlier, still only pulling back the cocking piece by hand.
Results of new test for lift:
There was no change in the amount of bolt lift with the bolt down hard, it jumped just as high but when I left a gap, bolt lift was near gone.
Same results as before.
My sign off on this subject:
I now understand more of the mechanics/magic behind bolt lift & my course of action will be to carry on as before.
I think the only way to eliminate bolt lift would be to remove metal to insure no contact between handle & receiver this however would cause considerably more stress where the bolt handle meets the bolt body resulting in them eventually going their own separate ways, so best to just leave alone or as Ed has recommended, replace the springs, this may well help keep lift down to a minimum.