Any cure for bolt lift?

[Alfred]

Don't know what else to call it.
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 ebhibits 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 sloppyness to the fit of bolt body to receiver.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Thunderbox]

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]

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.

This was helpful. Rather than inducing "friction" I gave it some thought and decided that "resistence" 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]

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]

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.
Theres 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 snuggly.
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]

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 burs or rough edges on the ends of a NEW firing pin spring and a NEW extractor spring is all that is needed.

[Alfred]

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.
Toque 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 undersied 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.
When my 327 Turbofire blew a donut it set off car alarms all over the parking lot as I drove by.
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]

Alfred AKA GunnerSam

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]

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.

[Alfred]

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.

Welcome aboard, nice that we have three, counting myself, visiting the thread who've actually examined the question. I see that you've recognized the main point I was making.

Ed merely reposted the bit about stoning and polishing the end coils of the spring from one of my old posts on another board.
Its been awhile but I remember that before he could get the drift of what I'd told him there I had to post a link to an Indian Engineering course that explained end toque.
That was a trip, I'd hate to have to trust to his engineering skills, perhaps custodial engineer was his proper title.
I think he got banned from that board shortly afterwards.

I'm begining to suspect that Ed has never even looked at an Enfield action, and just posts photos he's picked up on the net or dug out of old magazines.