Bolt Blow Out

[Beerhunter]

'Operator error' doesn't really cover it. The design was intended to prevent *any* operator action from causing the bolt to blow open.

In the case reported since WWII the bolt did not blow open and as you say the rifles were designed in order to negate this.

My point is that the failures that have been reported were not as catastrophic as the bolt blowing out.

The rifles in cadet hands were indeed standard No.4s with no modifications. As your your statement: "The (CCF) armouries I was aware of were managed by experienced ex-service personnel - often WW2 veterans - who knew the rifles from buttplate to muzzle." That was simply not the case at my school in the late fifties early sixties, I speak as a Cadet Armourer at that time. The rifles were cleaned and maintained by the cadets. In fact the whole contingent was run by the Cadet NCOs, the officers (masters at the school) being there almost as decoration. The small arms were thoroughly checked by REME but that was only annually.

The incidents in question were comparatively recently (within the last thirty year or so) and those "WWII Veterans" are long gone. The Adult Instructors in most of the Cadet Corps then and now are ex-cadets or "off the street" and so do not have that intensive knowledge of the kit.

It was extremely difficult to get details of these events at the time because our "children must not be hurt" culture. I'll see if I can find some references when I get a chance.

Edited 19 August , 2014 by Beerhunter

[calibre792x57.y]

One last point even a Ross shouldn't blow back the bolt - the interrupted thread locking action is capable of handling very high pressures, especially since it was designed with a view to firing the H.V. 0.280 in Ross cartridge. The problem is that if the bolt is removed from the rifle and then the bolt head rotated to the left the head will snap back to rest on the bolt body. In this position the bolt can be inserted into the rifle, picking up a cartridge from the magazine but the head won't rotate into the the threads in the receiver. It is possible to induce a breech explosion in this case. However as the point has already been made the root cause is poor training. I would hazard a guess that in the example quoted by MikB the cause may have been the ammunition which was likely to have been elderly and manufactured with some haste, (say for the Suez Crisis or Korea). It is conceivable that a 'hangfire' occurred and the cadet opened the breech w/out waiting the 15 seconds we were expected to count off. The cartridge fires and gives the bolt an assist in its rearwards travel. The bolt does not leave the breech but could still give the shooter a nasty poke. This could fairly be described as a 'blowback'. There has been a failure of neither design nor mechanism, just human, as usual. - SW

[MikB]

In the case reported since WWII the bolt did not blow open and as you say the rifles were designed in order to negate this.

My point is that the failures that have been reported were not as catastrophic as the bolt blowing out.

The rifles in cadet hands were indeed standard No.4s with no modifications. As your your statement: "The (CCF) armouries I was aware of were managed by experienced ex-service personnel - often WW2 veterans - who knew the rifles from buttplate to muzzle." That was simply not the case at my school in the late fifties early sixties, I speak as a Cadet Armourer at that time. The rifles were cleaned and maintained by the cadets. In fact the whole contingent was run by the Cadet NCOs, the officers (masters at the school) being there almost as decoration. The small arms were thoroughly checked by REME but that was only annually.

The incidents in question were comparatively recently (within the last thirty year or so) and those "WWII Veterans" are long gone. The Adult Instructors in most of the Cadet Corps then and now are ex-cadets or "off the street" and so do not have that intensive knowledge of the kit.

It was extremely difficult to get details of these events at the time because our "children must not be hurt" culture. I'll see if I can find some references when I get a chance.

My point was that failures to match design intentions do occur, even if they're extremely unusual in the case of Lee-Enfields, and there seemed to be no doubting the word of our RSM - a grizzled WW2 veteran, very capable and committed in matters of weapon training and maintenance and well-respected by cadets, parents and teachers alike - that the bolt had 'blown back'. The year was 1966 or 7. It'd be very interesting to know how it happened, and it may well have been played down or covered up in some way, but I've no doubt that the cadet suffered substantial injury to the right side of his face through some form of bolt failure.

Regards,

MikB

[Thunderbox]

I heard that the bolt was known to fly out if wet ammo is used hence the importance of keeping ammo dry I am sure a ballistic expert would be able to confirm this or not

Think about this logically: a weapon that catastrophically destructs every time it rains wouldn't be much use to an army, would it?

The technical answer is that, with dry ammunition, the brass case expands against the chamber wall as the propellant burns. Thus most of the recoil force is transferred to the barrel by the case "sticking" to the chamber wall. As a small part of the rear of the case is not actually inside the chamber, this part of the case stretches back and presses back on the bolt face. Once the firing sequence is over, the brass case shrinks back away from the chamber and bolt. Its this brass elasticity (and heat absorption) that makes it such a good material for obturating a breech loading weapon.

When the case is wet or oiled, there is a very small reduction in adhesion between case and chamber. In fact research showed that the oil/water is simply squeezed forward out of the way and ends up in the lead of the rifling - this is because the case expands from back to front, following the path of the propellant burn (as the burn starts about 1/4" in front of the case base, the rear part of the case expands from front to back. Hence the "ring" mark at this location on fired .303" brass).

Wet/oiled ammunition thus creates a slightly larger (c.20%) thrust on the bolt face. This fact is the basis for the wilder internet myths.

It was found that dry ammunition produces a pressure thrust on the bolt face of about 8 tons/sq inch, whereas oiled ammunition raised this to about 10 tons/sq inch. The standard proof test for a .303" was about 16 tons/sq inch. However testing showed that the No1 action could withstand repeated 30 ton/sq inch proof loads (source: Text Book of Small Arms; Strength of rifle actions).

Hence you can see that there is a vast safety margin on a Lee Enfield in .303".

Getting back to the oil/water that gets squeezed forward into the lead of the rifle: it was found that this made more worn rifle shoot much more accurately. It was thought that this was because the displaced oil/water created a gas seal around the bullet as it entered the lead. For this reason, and for reasons of preservation, rifle ammunition was assumed to be lightly oiled when in use. Some rifle ammunition was issued with a waxy coating already on it. In the field, a normal battle preparation by soldiers would be to clean ammunition and lightly oil chargers if necessary - to ensure efficient loading.

[MikB]

For this reason, and for reasons of preservation, rifle ammunition was assumed to be lightly oiled when in use. Some rifle ammunition was issued with a waxy coating already on it. In the field, a normal battle preparation by soldiers would be to clean ammunition and lightly oil chargers if necessary - to ensure efficient loading.

I found this bit astonishing. All the weapons training I ever had said 'NEVER OIL AMMUNITION !' I can see your preceding arguments could be valid in clean conditions, but apart from anything else the grit that oily bullets could pick up in a battlefield environment could do considerable mischief to bore and rifling in not very many rounds. The difficulty of maintaining consistency, too, would cause variations in POI as velocity deviations messed up the point in the recoil cycle and barrel harmonics as the round exited - whatever the theoretical accuracy obtainable in controlled conditions.

However, I don't really wanna wander off into an off-topic debate - I think we can agree that oil or water weren't a likely cause of the OP's incident.

Regards,

MikB

[Michael Johnson]

The explanation about the Ross Mk. III is correct. Later a pin was inserted in the bolt that prevented the shooter from improperly rotating it. I used to own two Mk. IIIs, one was had the pin, the other did not.

If the Canadian Army had stuck to the Ross Mk. II, which had solid lugs which would have handled rapid fire much better, it might have remained the Canadian rifle - but it was still too long and too heavy.

Michael

[Thunderbox]

I found this bit astonishing. All the weapons training I ever had said 'NEVER OIL AMMUNITION !' I can see your preceding arguments could be valid in clean conditions, but apart from anything else the grit that oily bullets could pick up in a battlefield environment could do considerable mischief to bore and rifling in not very many rounds. The difficulty of maintaining consistency, too, would cause variations in POI as velocity deviations messed up the point in the recoil cycle and barrel harmonics as the round exited - whatever the theoretical accuracy obtainable in controlled conditions.

However, I don't really wanna wander off into an off-topic debate - I think we can agree that oil or water weren't a likely cause of the OP's incident.

Regards,

MikB

Where this is described in the Text Book of Small Arms, they are referring to the tests and trials carried out whilst the Lee Enfield was being developed - ie from 1880-ish up until the outbreak of WW1. Of course in that era, the modern (sic) .303" round was still a very new device, and most weapons engineers would have been familiar with all the preceding types of oiled and waxed ammunition, British and foreign. Hence it was a very different era of weapon training and perception; I doubt even we have anyone on these forums who recalls those days! IIRC cleaning and wiping ammunition as a battle drill was taught right through WW2 and to the end of the .303" era.

I'm not sure that wiping ammunition with an oily bit of 4x2 would cause any significant problem. This would give a very thin smear of oil on the surface, so the quantity of oil will be extremely small (its of course worth noting that the Proof tests were done with the rounds dipped and dripping with oil!). This wouldn't attract any more dust than would - say - rainwater adhering to the raw brass. There is no evidence that such quantities of dust would have any effect on the function of the rifle at all.

As for shooting performance, I doubt that makes a difference either. We are not talking about the bore being oiled, so the only oil present would be the microscopic amount on the uncased surface of the bullet itself. Presumably this tiny amount would be combusted or shed as the bullet set up into the lead and rifling. As the bore itself is not continuously oiled, there ought to be no effect on the normal passage of the bullet through the barrel.

I must admit, I've found no shooting performance effect myself with oil-wiped rounds, or those that were packed with a wax coating (I had loads of South African U61 MkVII that had a sticky wax coating). I have routinely wiped ammunition, both old and tarnished surplus ammuntion on the civvy firing range - and military ammunition whilst on ops in sandy places.

[MikB]

Well, of course it depends on the oil and how much of it there is. Rangoon Oil, dried to a sticky goo on ammunition in Gallipoli, Mesopotamia, or the Western Desert in WW2 would certainly pick up more damaging grit than a microscopically thin coating of light oil similar to 3-in-1 in normal European environments. I always wiped ammunition with whatever clean rag or flanellette I had handy if it didn't already appear clean and dry - never wanted the risk to my score or bore by shooting it dirty!

I started off shooting my SMLE with a few boxes of South African U43, and IIRC it was dry and reasonably clean - though not very consistently annealed from the number of cracked necks and shoulders on the spent brass.

But like others, I don't believe any realistically-imaginable amount of oil or dirt could cause a bolt to blow back on any Lee-Enfield. Nevertheless, the OP has identified a documented case with similarities to something that happened in my youth, and I'm curious to know how it could arise.

Regards,

MikB