No.4 300 Winchester Magnum Test

[jmoore]

I've decided to try the limits of the action with some "real world" tests.

So, the caliber is going to be 300 or 303 Winchter Magnum, depending on the donor barrel, as brass is readily available (I hope) and the rim size is compatible w/ the existing bolt and extractor.

Need to set some parameters first.

Prefer to use factory ammo at first, as long as a reasonable supply can be found of partial boxes and such at the local gunstores. (If running a 303 bore, I've a large quantity of 174gr hpbt Sierra match bullets that I have no use for ootherwise as they're moly coated- if there are no objections those would be the default bullet.)

Dry cases and chamber for at least the first 100 rounds or so.

Questions:

-Headspace on the belt or the shoulder? (the second option tends to limit factory ammo to one brand as they aren't uniform- from past experience.)

-O-ring on the first shot or no? (This isn't a brass life test, but if it runs on a while I think my wallet could use the help,)

-POI observations or no? Not a great concern to me unless it indicates progressive failure of the action. Its a bother to do on a remote fire test rig.


i'd like to keep it as simple as possible, takes away from range time otherwise "productively" spent, plus I haven't a scadillion dollars- this is mostly a thought (read "costless") experiment gone horribly "real".

Information

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[Edward Horton]

Mr. Jmoore

1. Use the .300 Winchester Magnum, the case has more surface area than the .308/7.62 and has better “grip and traction” in the chamber.
2. No rubber o-ring and .016 head gap clearance, the dry case will stretch and absorb over 50% of the increased bolt thrust.
3. Wake me up when the test is over, the .300 Winchester Magnum only has 2,000 PSI higher chamber pressure than the .308 Winchester.

Why don’t you perform this test instead, use the .308 Winchester as the test cartridge, set the head space as close to minimum as possible and fire 100 oiled cases and check the actual headspace with a spent primer. Fire 100 more oiled cases check head space, etc. etc.

“An appeaser is one who feeds a crocodile, hoping it will eat him last.”
Winston Churchill

[jmoore]

I'm copy-ing myself from an old post as my likely chain of degradation/failure. I'm curious to see if it works out as follows:

Probable failure order of a No4's structural components:

1.Bolt head-
A)first excessive overturn (common)
B) then, fracture at the thread terminus (No No4 examples on hand, but I've several SMLE bolt heads broken off at this point.)

2.Bolt -
A) Forward face wear takes out most of these, I think.
B) Also the small lug in the striker cam area sometimes fractures- seen a few of those.
C) Bolt lug wear
D) Bolt lug shears off LH side - Never seen or heard of it though!

3.Receiver Body-
A)Bolt lugs wear through the hardened mating surfaces- Caught upon inspection- no real danger here.
B) Fatigue failure of RH receiver rail. Rifle contiues to function-sort of -probably begins to bind up on cycling and POI/accuracy go out the window.
C) LH receiver wall fails- a bad day! But there ought to be all the warning signs above.

Pure speculation, though. Tear this argument to shreds if y'all wish!

[Bindi2]

Why not just make your own proof or over proof 303 rounds and use plenty of oil. A lot cheaper easy to do and much simpler.

[jmoore]

Bindi2-No way to control or check chamber pressures when going past what's in the manual.

Mr. Horton-As to the chamber pressure being only moderately higher than 308W that's OK. I thinking the larger base ought to add some more thrust area. Shall we start boring math stuff already?

General poop-300 WSM is an option, but more pricey- want to contribute supplies or funds? I'm not proud...

Found a nickel plated M1917 barrel- Enfield rifling, but of "300" size, and easily threaded w/o shortening or other tricks. OK?

[Edward Horton]

Mr. jmoore

They made a movie about what your doing back in 1956. The name of the movie was called "The Enfield That Never Was". Clifton Webb put a life preserver on a dead Enfield cadaver and let it float ashore to fool the Germans during WWII.

This subterfuge was called "Operation Mincemeat" and the side that used the Enfield won the war. To make this test realistic you will need to handcuff a briefcase to the trigger guard and put all the Enfield manuals in it from the Knowledge Libraries.

P.S. I spoke briefly to the Finance Minister and she said there's no way she would invest money in a movie remake unless Clint Eastwood has a staring roll.

P.P.S. I contacted the prop department and they said it would be impossible to make a Mosin look like an Enfield for the new movie. This means we will have to go to the expense of computer generated graphics and use a lot of new boring math stuff calculations.

Are you sure you want to go to this expense when we already know who won the war.

[No4Mk1(T)]

Bindi2-No way to control or check chamber pressures when going past what's in the manual.

Mr. Horton-As to the chamber pressure being only moderately higher than 308W that's OK. I thinking the larger base ought to add some more thrust area. Shall we start boring math stuff already?

General poop-300 WSM is an option, but more pricey- want to contribute supplies or funds? I'm not proud...

Found a nickel plated M1917 barrel- Enfield rifling, but of "300" size, and easily threaded w/o shortening or other tricks. OK?

Well I for one am quite interested in seeing how this turns out. The M1917 barrel sounds like the way to go. I'm just wondering if you are able to Magnaflex (sp??) the receiver before and after to see if any fatigue/stress cracking shows up and where.

[Edward Horton]

Mr. jmoore

All kidding and joking aside, the British forum members are being hammered with vague comments about the strength of the No.4 and the 7.62 NATO cartridge.

The British military still to this day use the oiled proof test cartridge to proof their military small arms. This amounts to a 40% to 50% increase in bolt thrust from firing a dry cartridge. The first indication of excess bolt thrust would be a increase in head space.

Why not fire a .303 100/200 times with wet cartridges and check headspace, if their is no increase then do the same test with oiled cartridges. Then repeat the test with the .308/7.62 and see where we stand.

If I'm wrong I will send a new bottle of Caster oil to Mr. Parashooter and if I'm right Mr. Parashooter can send me one of his Enfield's with the tightest head space (just kidding)

I think this type testing would be in the "Myth Buster" category and give us some real world answers. I will donate 200 Greek HXP cases for testing purposes and others can chip in as they see fit.

When the testing is done we can write a book on the subject and then all of us will be rich and famous.

Here is what I think the new book should look like. What do you say Mr. jmoore should we give it a go?

[Brit plumber]

A little off topic, but has anyone seen or have a copy of the video made by UK MOD showing a N04 firing a round loaded with PE4 explosive?

[Maple_Leaf_Eh]

A little off topic, but has anyone seen or have a copy of the video made by UK MOD showing a N04 firing a round loaded with PE4 explosive?

Why bother? Salting explosives-loaded ammunition in enemy ammunition dumps is nothing new. So, just who is the enemy in all this testing?

I am curious why tempt fate rechambering a No.4 to .300 WM, when P14s in .300WM are a well known and long trusted conversion?