|
Enfield action strength |
Post Reply 
|
Page <123 |
| Author | |
Shamu 
Admin Group 
Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510 |
 Post Options
 Thanks(0)
 Quote Reply
 Posted: June 20 2023 at 6:11pm |
|
Never heard of a Pakistani No4 7.62 conversion?
|
|
|
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
|
|
 |
|
|
A square 10
Special Member
Donating Member Joined: December 12 2006 Location: MN , USA Status: Online Points: 16997 |
Post Options
Thanks(0)
Quote Reply
Posted: June 20 2023 at 8:13pm |
|
not converted , purpose made
|
|
|
|
|
britrifles
Senior Member 
Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: June 21 2023 at 3:42am |
My mistake, I was thinking of the Ishapore 7.62. Did Pakistan make No. 4 7.62 rifles? I would think the Pakistani No. 4 would have the same strength as the British and North American rifles had, if they were made from the same materials and same heat treatment. But, as in all metal structures, there are small variations in strength properties.
|
|
|
|
|
W.R.Buchanan
Senior Member
Joined: September 21 2014 Location: Ojai CA Status: Offline Points: 373 |
Post Options
Thanks(0)
Quote Reply
Posted: June 21 2023 at 8:57am |
|
FYI guys I found this neato Calculator for converting CUP to PSI.
Wonder if anyone actually knows what the #4 actions were Proofed to? "Strong Enough," is not an answer? It is more of a Question? Randy
|
|
|
It's not how well you do what you know how to do,,, It's how well you do what you DON'T know how to do.
|
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: June 21 2023 at 9:27am |
|
Randy, yes, the proof cartridge pressures are documented in various writings; in Reynolds book for sure. IIRC, it was 25 TSI.
But, the "tons per square inch" units of pressure measurement does not correlate to CUP or PSI standards used in the US and Europe, but refers to the unique British system of measuring chamber pressure (axial copper crusher method). Somewhere on this forum is a post I wrote that describes it; extracted from a NRA American Rifleman magazine article in the 1960's. The British system of Axial Pressure measurement typically gives a lower value than CUP (at the same actual peak pressure); IIRR, in the range of 80 to 90% of CUP. A dry proof round was used to proof the barrel, and an oiled proof round was used to proof each action. The 18.5 TSI markings on the LE's released from service refer to the typical pressure of the MK 7 service cartridge, not the proof pressure. If you convert that to a pressure measurement in lbs/in^2 gives 41,440 psi (2240 lbs in a British long ton); which you can see, is less than the usually accepted 45,000 CUP (US system of radial copper crusher method) as a safe maximum load for use. |
|
|
|
|
Long branch
Senior Member
Joined: January 08 2014 Location: Georgia, USA Status: Offline Points: 251 |
Post Options
Thanks(0)
Quote Reply
Posted: June 21 2023 at 3:37pm |
|
I just love how this thread keeps "waking up" after long periods of inactivity. :)
|
|
|
|
|
Sapper740
Senior Member
Joined: July 15 2021 Location: Texas Status: Offline Points: 1737 |
Post Options
Thanks(0)
Quote Reply
Posted: June 22 2023 at 2:27am |
|
B.O.T.R. (Bloke on the Range), British Muzzleloaders, C&Rsenal, Forgotten Weapons are my 'to go to' YouTube posters for the most informative videos regarding firearms.
|
|
|
|
|
Honkytonk
Senior Member
Joined: December 30 2017 Location: Brandon Mb Status: Offline Points: 5190 |
Post Options
Thanks(0)
Quote Reply
Posted: June 22 2023 at 4:40am |
|
He's pretty good.
|
|
|
|
|
450 Fuller
Groupie 
Joined: June 07 2022 Location: New Mexico-AK-A Status: Offline Points: 48 |
Post Options
Thanks(0)
Quote Reply
Posted: August 24 2023 at 3:00pm |
|
Some of you senior lads might remember my
"strength tests" of a 2a1 awhile back. It was the bolt/extractor fatigue and cartridge pressure issues that rendered that rifle inoperative. Subsequent test loading with 7.62 brass and 150 gr jacketed bullets have proven successful. I have a M 98 custom Mauser that was well done by a Colorado gunsmith in the late 1950s. It is chambered in 30-06 Ackley Improved, and an accurate rifle it is. Strong action that digests fire-forming case loads quite well. New powders allow the 30-06 Ack Imp to reach 300 H&H velocities safely within the 50 K psi range. Because of 1895 Winchester and other older rifles in 30-06, W-W and R-P were slow to offer ammunition in 30-06 loaded to the same pressure levels of the 270 WCF. (Though the identical modern rifles were chambered in both cartridges.) That practice ceased some years ago. |
|
|
Only the dead have seen the end of war-Plato
Socialism-The equal sharing of misery-Churchill MACVSOG-5th Special Forces Gp |
|
|
|
|
450 Fuller
Groupie
Joined: June 07 2022 Location: New Mexico-AK-A Status: Offline Points: 48 |
Post Options
Thanks(0)
Quote Reply
Posted: September 10 2023 at 10:06am |
|
While I got my 2a1 .308/7.62 back working normally, all bullets and loading will err on the side of caution with a dry chamber. Bullet weight kept to 150 gr
in the interest of pressures. Bottle neck cartridges tend to increase in pressure as they are reduced in caliber (308 vs 243) all other areas being equal-as more powder and heavier bullets are used. Their cousins with relatively straight walled cases are more forgiving, as is the use of black powder. (As in 45-70, 45-90, and even mildly necked 577-450 BP used in the Martini derivative rifles.) Years ago, either in the American Rifleman or Rifle Magazine, an author opined that the rifles used in WWI and partly in WWII could be classed as: The Mauser was a design adopted to war or sporting use; the Springfield was an excellent sniper/target rifle, while the SMLE-Enfield design by James Paris Lee may have been the best design for combat in the trenches and general warfare. Older threads need awakening as the tree of liberty needs watering: they reflect research and experimentation not easily found. |
|
|
Only the dead have seen the end of war-Plato
Socialism-The equal sharing of misery-Churchill MACVSOG-5th Special Forces Gp |
|
|
|
|
Rossfield
Groupie
Joined: June 08 2024 Location: Nova Albion Status: Offline Points: 37 |
Post Options
Thanks(0)
Quote Reply
Posted: April 02 2025 at 4:08pm |
|
It was never stated if the bolt was an original match to the FTR'd
rifle or not. If the contact between the two lugs is not equal a
fracture would not be surprising at those loads. Would have been nice
to see the actual bearing surfaces on the bolt lugs to see if there was a
proper contact at the outset. Rather than wrestling with the HS gauge Bloke could have just fed it up under the extractor from the mag well.  Bit surprising he can't tell it's a Fazakerly rifle from the markings shown.With
all due respect to those involved, the RFD in particular, what they are
describing as a "flaw" to me looks like the typical hardening marks
with that yellowish tint. This quite noticeable on some Long Branch
actions when they are "in the white". There
is no sign of any previous crack such as dirt ingress or corrosion and
the line along which the rear lug has fractured quite likely
approximates the point of separation between the hardened and unhardened
parts of the small lug. Notice the sharp-pointed "ramp" that remains
of the lug: that is is approximately the hardened portion of the lug,
which remained attached to the bolt body, albeit the broken off rear
portion! What I suspect happened was that
assuming the contacts between each pair of lugs was even at the outset, the
much smaller recoil lug in the rifle body was increasingly "set back" by
the five or six oiled rounds until finally the last round hammered the
bolt lug into the now set back receiver lug causing an impact shock that fractured it
and the bolt. It is surprising to see how small the actual contact
areas are on both pairs of lugs. So, one
or two
oiled .300 Win Mag rounds would have passed, but more is too much to
ask of an action designed for much less. Still, the inherent safety
displayed is impressive: the main lug held. Assertions were made in the
past about
the function of proof rounds in "setting back the recoil lugs"; which
was apparently implied that doing so would help to equalize the
load bearing between each pair of lugs(?). That may be so on actions
with
equally sized lugs, or less hard-faced lugs, but I wonder now if such
"setting back" had any beneficial effect on the Lee Enfield given the
unequal load-bearing capacity of very different sized lugs, particularly
at the upper end of their load capacity? |
|
|
|
|
britrifles
Senior Member
Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404 |
Post Options
Thanks(0)
Quote Reply
Posted: April 02 2025 at 4:34pm |
|
I did a rough calculation some time back on the bolt locking lug bearing stresses from bolt thrust loads. It of course had some assumptions, such as the amount of analytical bolt thrust loads reacted by the case walls gripping the chamber. These stresses are very high, depending on the measurement/assumptions made of how the contact surface area.
I’m fairly confident that a proof round does cause some localized yielding (plastic deformation) in compression of the lug surfaces, either the bolt lugs or receiver recesses, or both, depending on the material properties/hardness. This permanent set would then increase the total contact surface area and reduce bearing stresses for subsequent rounds. Service ammunition however could not cause yielding, for if it did, headspace would rapidly increase. I think what happened here is low cycle/high load fatigue cracking. Loads were very high here and the stress concentrations in the tight transition radius between the lug and bolt body are high. I wouldn’t be surprised if the long rib lug also had a fatigue crack, but because of the much longer rib, it will sustain a longer fatigue crack prior to failure than the short lug. I’ve reconsidered my opinions on the need for equal lug contact somewhat, at it may be favorable to have slightly more contact area (under “no load”) on the long rib lug than the short lug for the above reasons. |
|
|
|
|
Rossfield
Groupie
Joined: June 08 2024 Location: Nova Albion Status: Offline Points: 37 |
Post Options
Thanks(0)
Quote Reply
Posted: April 03 2025 at 5:50pm |
|
The Textbook of Small Arms 1929 mentions how in tests done at Enfield, a barrel inserted into a receiver without threads: that is simply slid into the action, fired normally and was not dislodged if every trace of oil or other lubricants were removed from the case and chamber. Any amount of oil on either would cause the barrel to be "violently" blown clear of the action. The conclusion was that with proper case adhesion during firing the backwards thrust on the bolt face is minimal, but anything which inhibits adhesion like oil, water or grease has the effect described. Thus an oiled proof round would transfer all or most of the thrust onto the bolt and if "set back" occurs, I would agree with your description of the process, except that the very different sizes and therefore strengths of the large and small lugs would to some extent mean much greater loading on the small lug. To what extent the large lug and bolt compress under such full recoil, or the bolt flexes, I don't know, but it could be that the set back in this case was more or less equal, unlike what I hypothesized above, to the extent that the small lug could tolerate it, after which it simply fractured, starting a break which continued through the bolt body. It's not unknown for the small lugs to break off without fracturing the bolt body and I have such a bolt here in a bag of FUBAR parts IIRC.  |
|
|
|
|
Rossfield
Groupie
Joined: June 08 2024 Location: Nova Albion Status: Offline Points: 37 |
Post Options
Thanks(0)
Quote Reply
Posted: April 03 2025 at 5:56pm |
|
Second screenshot  |
|
|
|
|
Rossfield
Groupie
Joined: June 08 2024 Location: Nova Albion Status: Offline Points: 37 |
Post Options
Thanks(0)
Quote Reply
Posted: April 03 2025 at 5:57pm |
|
Third screenshot showing forward face of small recoil lug  |
|
|
|
|
Post Reply
|
Page <123 |
| Tweet |
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Topic Options
Shamu wrote: