Home Forums Hunting & Shooting Mausers and Military Rifles Rifle, No. 4 Mk I, 300 WM conversion.

Rear locking lugs, eh?



Nice little twist at the end, also.

Excellent.
It gets quite old to constantly read posts, by those that have absolutely no experience with the Lee Enfield, spouting the weakness of the action, excessive headspace, etc.
The Lee design started production beginning in 1879, adopted by the US Navy then, modified to 303 and adopted by the Brits in 1888, and continuing in service with the Canadian Rangers until 2016 - considerably longer than the service life of the Mauser 98.
Not bad for a rear locking lug design.

As you were.
Remington-Lees.

The British adopted The Magazine Lee–Metford for service in 1888, with the .303 black-powder cartridge.

James Paris Lee was a gifted Scot, indeed.

edit for brain thingy.

Yep, and every clip type removable magazine can be traced back to the mind of Mr Lee.

Interesting. Have you butchered it yet? If not, put it back in the safe and go find you a Remington 700 in .300 WM and save yourself the trouble. You ever heard of excessive head space? You're about to.

Implying SMLE failure due to excessive head space?
Wherever did you get that idea from?

Yes, that's right - never heard of a rifle blow up from excessive headspace. At worst a head separation is an inconvenience. Excessive headspace beyond that and the cartridge won't even fire

Just somebody else with a keyboard.

Humorous fellows there,

"Prayer" at the beginning,

"It's been reamed, thoroughly reamed',

and having the cameraman come in for the "obligatory entry shot".

gun porn at it's British finest.


Thanks, as owner of a sporterized #4Mk1* your thread caught my eye.

Geno

Good science.


Yes we can be a bit naughty, but we have been doing it for quite some time.

I see you are relatively new to these parts Fawkes. Welcome, and please do continue to entertain us Yanks with your science.

Geno

Yes, and blow something else up. As an idea I've never seen a blown up 22 - I've seen bulged barrels but nothing worse. Maybe ream out to 22mag and come up with some hotter loads.

(The older CZs have two lugs but the newer only have one I think - always wondered how much contingency was built into the strength of the action.)

Film it and include a buxom blonde assistant.

That was fascinating but incomplete. The actual strength of the Lee Enfield, especially the No. 4, has not been questioned too much but the rigidity has. There were no measurements of the fired case to gauge the amount of stretch which would have been interesting. However, because of the fractured lug, any findings would be invalid anyway.
The Lee enfield action flexes. This is demonstrable. The thing is this; the flex is why it works so well for the intended purpose. If a cartridge is a little on the tight side, the bolt can be closed on it because the action flexes and because the locking lug seats are angled which provides a lot of force. The lugs on the P-14 are angled as well but the P14 does not flex so the same scenario may result in a jam.
In this case the fractured lug probably occurred during the second 7.62 proof firing but did not show up until it failed. Close inspection when the gauge first indicated an increase in headspace might have shown the crack. Forcing the bolt down on the gauge may have hastened the failure.
I have fired a No1 MkIII to failure and the lugs never did fail. The bolt actually bent and the bolt head was partially sheared away by escaping gas. I don't recall what the final load was but it was well beyond what one would expect any rifle to handle.
A neat video but I will second the request for the buxom blonde. GD

Fawkes, I'm curious. I know why you made the video, but I think you should have considered bolt thrust, not the pressure generated by the cartridge. Cartridge pressure acts upon the bolt face, which in turn, acts upon the lugs. There is an approximate 32% pressure increase on the bolt face, transferred to the lugs. This is from 303 to 300 WM.

303 British - approx 3900 kgf bolt thrust
308 Win - approx. 4660 kgf bolt thrust
300 WM - approx. 5700 kgf bolt thrust

MAP x Aext = kgf

The No 4 action was designed to shoot the 303 British, which generates 3900 kgf of bolt thrust. How long can the mechanism take the increased bolt thrust generated by the 300 WM before it fails? Rather than compare the bar (pressure) increase from 308 to 300 WM, you should be comparing the bolt thrust (kgf) of the 300 WM to the 303 British. The test is really about how much abuse the lugs can take, going from a relatively sedate 3900 kgf to 5700 kgf. After all, with the exception of the bolt face, the bolt is original issue.

I think we can all accept that increasing the pressure to 300 WM levels would eventually render the rifle unserviceable. How many shots will it take before the bolt distorts? You will need to repeat the test. Because of the design, I expect the bolt should twist, but not come apart catastrophically.

Have fun!

I suspect that the N0.4 might go on for quite a long time simply because it does flex and the stress is not concentrated in a small area. Of course, the flex of the receiver is why the small lug is most likely to be the fracture point. Under load, the right hand side of the receiver stretches more than the more robust left side. which loads the left lug to a greater extent. The bolt will tend to flex outward (to the right) which tends to bend the bolt behind the left lug to the right as well; with the left, smaller, lug being the pivot point. For this reason, it wouldn't surprise me if the left hand lug was, consistently, the point of failure.
Another question I have for Fawkes would be, was there any apparent damage to the receiver or, with the substitution of another bolt body, was the rifle still serviceable? GD

After reading these postings all I can say is I don't think it's a good idea......

I have overloaded No 4 Mk I rifles.

I have done a stress calculation on the bolt. It is springy with the lugs at the back. The thin walls of the bolt tube compress for a millisecond and stretch the brass beyond elastic into plastic deformation. Ackley was right about this in the 1960s.

~~ 2002 all of the USA and Canada seemed to be out of longer bolt heads. Making heads from surplus blanks has clocking problems.

I have made a fixture for soldering a shim to the bolt head to fix the headspace. I read a message from a Brit in Florida that did the same for No 1 Enfields.






That last pic is a 308 Ishapore. It shoots steel cased ammo best.

I would like to say:
I have converted VZ24 Mausers to 7mmRemMag and 300WM and got them to feed.
I have converted 91/30 Mosin Nagants to 7mmRemMag and 300WM and got them to feed.
The only cartridge I would consider for an Enfield conversion is 25 Krag Ackley.


I did convert a 30/40 Krag [nearly the same cartridge as the 303 Brit] last week to 25 Krag Ackley. I also made a 3rd action screw in the front ring.

I have a Enfield Mk 4 that was rebarreled to a 219 Zipper Ack Imp. Been shooting it for year. Its a great shooter.