Strength Of Lee Enfield Action

[Thunderbox]

Within @ the last 5 years I've seen 2 people shooting No4 rifles have their glasses broken when the striker struck the lens after punching a hole into a primer. Luckily no eye damage occurred.

How does that happen, given that there is a compressed spring preventing the pin coming back much beyond "full cock"? Did the base of the bolt shear off, or the collar on the firing pin?

I've had dozens of pierced primers, and always found that the primer gas eventually escapes around the side of the pin (normally blowing gungy oil out of the bolt body!) as soon as the cocking piece reaches its limit of travel. There doesn't seem to be enough energy in a primer to cause anything outside the normal working tolerance of the bolt mechanism.

[Beerhunter]

The one I examined some years ago blew the extractor and bolt head side out, and bent the rear of the action down so the bolt could not be withdrawn, and the bolt body was "dolphined" above it's "race". The post mortem indicated that the previous bullet had not left the barrel IIRC.

As to "handling gas" better than a mauser, I disagree. Within @ the last 5 years I've seen 2 people shooting No4 rifles have their glasses broken when the striker struck the lens after punching a hole into a primer. Luckily no eye damage occurred.

What on earth are those people doing with them? I have been shooting Lee-Enfields for over fifty years now and, in common with other posters, have NEVER seen a catastrophic failure. Nor have ever seen a pierced primer cause that effect.

[Simon P]

I have two articles from the 80s written by a Major Yearsley, one was on a No4 that had a barrel obstruction which caused a large hole in the barrel just behind the front sight, the second was a breeech explosion on a L1A1 SLR.

When I get home next week I will scan & post them

[Badger]

Speaking of damaged Enfields ...

Another old thread from a few years ago that was a really good read ....

Battle Damaged Enfields?

Damn, you forget sometimes, that we have some great content contributed by so many terrific Enfield collectors and members.

Regards,
Doug

[Peter Laidler]

As a part time physics teacher and one who's conversant with Boyles laws of gas and one who's been in the Armouring game a LONG time, I would seriously question the notion that a ruptured primer would produce sufficient gas to overcome the striker spring sufficient to compress it and.... on and on..... while at the same time, always taking the line of least resistance - as a gas will always do - past the non existant gas checks and venting in every direction at every opportunity .......... and ...... Oh, save us from this please..............
I'll say no more for fear of losing my usual diplomatic touch with words.

[Bruce_in_Oz]

P. O. Ackley did a study post WW2 in which he set out to evaluate strength and gas and pressure "management" of various actions.

Top of the pile was the (pre-war production) Type 38 Arisaka.

SMLEs came in at lucky number 13, ahead of the Arisaka type 99.

Lee Enfields basically "bend" when subjected to silly pressures. The right side rail stretches and the bolt ends up sticking out the side. BUT, the rear shoulders NEVER fail. If you look at one, it is obvious that there is a lot more steel holding the bolt in than in a Mauser. The other side of that is, as the stress path is much longer than in a Mauser, the stress is distributed over a greater amount of material; thus bending instead of bursting.

That said, possibly the strongest military action ever built was the M-1 Garand. Carefully designed and then carefully made from heat-treated 8620 steel, these things are incredibly tough. You might drive the bolt back so hard it cracks the thin rear wall of the receiver, or you might crack the bolt, but the lock-up will most likely never fail.

I agree that most problems come from dodgy ammo. Too much propellant, the WRONG propellant, ancient, decomposing propellant will generally do damage. Obstructions in the bore and damaged strikers and striker holes are the next cabs off the rank. Another BIG one is untrimmed brass. Who knows how many otherwise good rifles have been damaged or destroyed by the massive overpressure caused by excessive case length. READ the reloading manuals on this subject.

[ireload2]

As a part time physics teacher and one who's conversant with Boyles laws of gas and one who's been in the Armouring game a LONG time, I would seriously question the notion that a ruptured primer would produce sufficient gas to overcome the striker spring sufficient to compress it and.... on and on..... while at the same time, always taking the line of least resistance - as a gas will always do - past the non existant gas checks and venting in every direction at every opportunity .......... and ...... Oh, save us from this please..............
I'll say no more for fear of losing my usual diplomatic touch with words.

It is widely known to anyone that reads and reloads that gas venting through firing pin holes blows firing pin assemblies back.
As a part time physicist you should be able to calculate the gas volume that can escape through the firing pin bore during the time that same gas is propelling the bullet down the bore. Now considering that escaping gas has a much higher velocity than the bullet you should easily understand how the firing pin can be blown back.
You have the area of the firing pin spring flange being acted upon by the gas. I could calculate this pressure if you wish but I am sure you can do it too.

[newcastle]

Errrr. I'm not a part time physicist. So if you have some fab details that I can't figure out, tell me please. What is the risk here? It's all very well people hiding behind pretend names and stuff on our internet, but if there's something we should all know then tell us rather than being a smartypants.

[PrinzEugen]

Oh gawd here we go again - the usual suspects are coming out of the woodwork - where's that new mod when you need him! Two similar threads in a week - these things must be cyclical.
I await with anticipation large rafts of copy and paste evidence together with diagrams.

[jmoore]

Oh gawd here we go again - the usual suspects are coming out of the woodwork - where's that new mod when you need him! Two similar threads in a week - these things must be cyclical.
I await with anticipation large rafts of copy and paste evidence together with diagrams.

If you take the bait and allow the ruckus to commence, I might have to finish the .300 Win Mag project that was started some time back during the last big outbreak of this silliness:


A poor old No.4 action with a nickel plated M1917 barrel cobbled on. (the nut is for easy headspace adjustment- no front sight was required...)