Made it to the range today with My Rifle No5 Mk1 "Goobermint Model Sporter"

[BFMIN]

Fired 6 rounds from it, total

“Doco Overboard” got to play too. It doesn’t kick as hard as he remembered, but is just as loud as he remembered..
The good news.
The zero is good.
The full case (350 rounds) of Radway green '45, Mk VII ball is Good to go! (I thought it might be having been sealed in a spam Can in a sealed create.) No click-BANG or hang-fires at all.
.
The bad news.
The blasted "correct" Galvanized specially funnel for "boiling out" corrosive salts won't fit the action with the scope mounted & its not a Q.D type mount! (Shown here on my Lithy SMLE)
Cordite/corrosive is really filthy stuff even with so few rounds fired.
I have thoroughly cleaned with water-based solvents, alternating bore cleaner & dry ones, till a patch came out light grey, not the color of The Earl of Hell's back pocket! More copper solvents are soaking in overnight. I'll do my usual cleaning in the coming day or two to be sure.

 

[Threeband]

The Russians would piss down their barrels to flush out the corrosive salts.

That funnel turns the rifle into a handy urinal.

Damn clever accessory.

 

[mawkie]

Yes indeed, that funnel looks so familiar. A must have for any Enfield shooter/collector.

 

[SRice]

If you care about the throat of that rifle, I wouldn't keep shooting the cordite ammo. It will wear down the throat very very fast, before you even finish that case of ammo.

 

[Doco Overboard]

If someone’s busting off some of that RW Green at you you’ll need more than a funnel that’s for sure.
A garden hose to wash your britches out would be more appropriate from the working end.
Perfect truck / getaway gun.

 

[BFMIN]

If you care about the throat of that rifle, I wouldn't keep shooting the cordite ammo. It will wear down the throat very very fast, before you even finish that case of ammo.

You have got to be kidding me!
That bore's already seen corrosive/cordite ammo. As have probably 90% of all the Lee Enfields ever sold have.
If that were even remotely true none of the Milsurp Lee Enfields sold would ever be able to "Pattern" much less "group".

 

[Pureblood]

 

[SRice]

You have got to be kidding me!
That bore's already seen corrosive/cordite ammo. As have probably 90% of all the Lee Enfields ever sold have.
If that were even remotely true none of the Milsurp Lee Enfields sold would ever be able to "Pattern" much less "group.

Yeah, so cordite is the issue here, not the corrosive primers. This has been discussed a lot amongst Enfield collectors:

"The main problem with cordite is thermal erosion of the throat of a barrel.
The over the charge card wad cuts down erosion a bit, but using cordite loads in a very good barrel will turn it into a mediocre barrel after as little as 200 rounds.
If you have a .303 rifle that handles boat tail bullets well, even a few hundred rounds of cordite can ruin the throat enough to cause boat tail bullets to keyhole at less than 200 yards. EGB Reynolds wrote about this in testing the use of Mk8z ammo in No.4 rifles during WW2.
Contrary to propular beliefs the British used enough M7z and Mk8z Nitro-Cellulose loaded ammo that many Enfields may have never had cordite used in them, those barrels that never had cordite used in them usually still have good throats.
Other rifles rebarreled before being put in storage would have excellent bores that cordite can ruin very quickly.
Use of cordite will turn a 2MOA rifle into a 4-6MOA rifle after awhile, with groups when using modern ammo often being even worse with keyholing likely.
On the other hand if cordite rounds are used exclusively accuracy drops off more slowly.
The Mk7 bullets bump up well with the heat and shock of ignition of cordite, off setting the effects of erosion, and the over the charge card greatly reduces blowby. Theres no card wad in Mk7z or Mk8z.
In tests using Mk7 with the card wad removed completely ruined accuracy within 1500-2000 rounds. They had tried this because the card wad in use at the time chipped wooden propellors and damaged doped fabric when used in synchronized guns of WW1 aircraft. They then developed a wad of strawboard that disintegrated on leaving the muzzle. The RAF contracted for their own specially marked supplies of .303 from 1918 onwards."

//

'Regulations For Army Ordnance Services', Vol.3, Pam.11A (1949) comments:-

APPENDIX 15

(referred to in para.29)

USE OF .303-IN CORDITE AND N.C. AMMUNITION

1. The action of Cordite propellant in the barrel of a .303-in. weapon is quite different from that of N.C. propellant.
Cordite gives a rapid build-up of pressure with great heat, leading to pitting and erosion of the chamber end of the barrel.
N.C., however, gives a more gradual build-up of pressure with less heat, and this in turn gives uniformity of barrel wear from chamber to muzzle, the amount of pitting and erosion being greatly reduced.

2. With Cordite propellant, set-up of the bullet is most pronounced and even when the chamber end of the barrel is well worn, the muzzle end still has sufficient rifling left to impart the necessary spin. As the wear advances up the barrel, so the accuracy of the weapon is progressively reduced.
With an N.C. propellant, set-up of the bullet is slow and by no means so pronounced, due to the more gradual building up of pressure. The barrel retains its original accuracy until wear reaches a critical stage, when a sudden falling off in accuracy occurs.

3. It can be seen by comparison with the effects of barrel wear that to use N.C. ammunition in a barrel which has fired Cordite will give serious inaccuracy in flight, whereas the use of Cordite ammunition in a barrel which has fired N.C. gives good accuracy, but serious changed the wear pattern of the barrel.
In the first case, i.e. a weapon which has fired Cordite ammunition the barrel will be eroded and fissured in the first few inches up from the chamber, the part in which obturation should occur. The poor set-up of the bullet, in the N.C. cartridge is not sufficient to give good gas sealing in such a barrel and the bullet does not, therefore, receive the maximum impulse. The resultant loss in velocity and instability due to lack of spin lead to a high degree of inaccuracy.
In the second case, Cordite ammunition fired from a barrel which shows uniformity of wear from firing N.C. ammunition, has an adequate reserve of set-up that ensures full gas sealing, with satisfactory velocity and spin. Unless the barrel wear is in a advanced stage due to firing a large number of N.C. rounds, there will be no immediate appreciable loss in accuracy. Furthermore, the decline in accuracy for Cordite ammunition will follow the normal gradual fall-off experience in weapons firing Cordite alone, as the wear at C of R progresses.

4. Trials have proved that even if only a few rounds of Cordite ammunition are fired from an "N.C." barrel, the ensuing accuracy life when N.C. is subsequently fired is reduced considerably. The occasional and restricted use of N.C. in a "Cordite" barrel will however, have little effect on its ensuing accuracy life for Cordite, although naturally the fire of N.C. will not be very accurate.

5. The effect of wear of barrels can be determined by firing shots through a paper screen at 100 yards. If, on examination of the screen, all shot holes are not perfectly round, then the barrel is no longer fit for use.
The danger lies in the fact that bullets fired erratically from badly worn barrels may overcome their instability in flight and take up a steady flight in the direction in which they happen to be pointing, with short-ranging and disastrous results if used for overhead fire. Except under these conditions of long-range firing there is no risk involved, though in normal range firing inaccurate fire will result.

6. The following instructions regarding the use of .303-in ammunition have been issued to users and are governed by stocks and types of ammunition and weapons in current use:-

(a) .303 in. Vickers M.G.s in M.G. Bns.

(i)Mk.8z only will be used for overhead firing.
(ii) Mixed belts, i.e. Ball, Tracer, A.P., etc., will NOT be used.
(iii) Any barrel which has fired Cordite ammunition will NOT be used for N.C.; barrels will be stamped “7” on the trunnion block and returned to R.A.O.C. through normal channels.
(iv) Barrel life for N.C. will be assessed by unit armourers using the appropriate gauges.

(b) .303 in. Vickers M.G.s in A.F.V.s.

Here the overhead fire problem is not considered; the range is usually less than is the case with ground M.G.s. tracer ammunition is required as an aid to fire control, and prolonged fire programmes are not envisaged. Special mixed belts of Mk.8z and Tracer are provided in boxes clearly marked “For use in A.F.V.s only”. The reduced life of the barrels is accepted.

(c) Light M.G.s.

Cordite ammunition normally will be used. N.C. ammunition, however, gives a relatively small flash at night and if the Bren is being used for a special purpose, e.g., on a patrol, its use is permitted.

(d) Rifles.

N.C. ammunition will not be used in rifles except in such circumstances as quoted in para. “(c)”
above, if necessity should arise.

7. Belt packed S.A.A. for M.G.s is packed in boxes which are clearly marked with labels or stencilling indicating its proper use. It will never be de-belted and used for practice purposes in L.M.G.s or rifles.

8. It must be noted that the above restrictions apply only to ammunition fired from British weapons. All American ammunition is N.C. loaded and their weapons are designed to fire it satisfactorily.

 

[Doco Overboard]

The small arms treatise has the correct information for continually firing manually operated small small arms and explicitly states how the .305 plug is to be applied in the armorers workshop. Thousands is the term used as a matter of fact.
Elsewhere in the text additional information is supplied in exquisite detail regarding the development,pressure, testing, thermal characteristics, effects of cordite ammunition to the nth degree as well as accuracy of machine guns using cordite loaded ammo and the maintenance of such systems so its important to not conflate information from various sources into a cut and paste job that may have merit but paints with an overly broad brush.
Ill have to go back and familiarize myself with wood chips and propeller blades because I may have glossed over that part but that's not ringing any bells for me at the moment, probably because its not there that for which I'm certain of.

 

[Doco Overboard]

I just did a quick review of Reynolds.
I would recommend any serious enthusiast to have a look at that one too, and reread when and where necessary.
It was published in or thereabout 1960 and a great read if I'm not to far of base, and.... my memory may suffered since last time I read it in depth.
Otherwise Im sticking with the Hythe and Woolwhich bunch prior to end of hostilities in WWI.
Where as a matter of fact and side note, more casualties were presented to the allied forces not including Germany in the last five hours or less of the war, than the total number accumulated during the allied invasion of Normandy some years later.
I know that's not particularly germane to the totality of the conversation at present but neither are corrosive primers to barrel life and cordite ammo. More rifles failed the gauge in less than a thousand rounds to overzealous cleaning than firing 350 rounds of mk7 ammo as page 360 of the text book indicates.

 

[BFMIN]

Well that's a nice piece of theory.
I don't deny Cordite is more erosive than Nitro powder, and I never have. I also never said it was the Corrosive Primers that were the problem. They just require cleaning for corrosive, no more.
Please stop shoveling words into my mouth I never uttered.

But we're talking multiple Thousands of rounds & as I stated this bore has already seen cordite, as has my BSA 1914 SMLE & My Savage No4 Mk1*. Both shoot within spec.
As a a counterpoint I present all the accurate Long Lees, Lee Metfords, LLEs, CLLE's, SMLE no 1MkIII ( & MkIII*), No4 Mk1, Mk2, Mk 1/2, Mk1/3, & everything else firing the Mk 2~7 .303 British round for over 100 years, most of which can still group to meet or beat Factory spec.
Explain that away.

 

[SRice]

Well that's a nice piece of theory.
I don't deny Cordite is more erosive than Nitro powder, and I never have. I also never said it was the Corrosive Primers that were the problem. They just require cleaning for corrosive, no more.
Please stop shoveling words into my mouth I never uttered.

But we're talking multiple Thousands of rounds & as I stated this bore has already seen cordite, as has my BSA 1914 SMLE & My Savage No4 Mk1*. Both shoot within spec.
As a a counterpoint I present all the accurate Long Lees, Lee Metfords, LLEs, CLLE's, SMLE no 1MkIII ( & MkIII*), No4 Mk1, Mk2, Mk 1/2, Mk1/3, & everything else firing the Mk 2~7 .303 British round for over 100 years, most of which can still group to meet or beat Factory spec.
Explain that away.

How is British Ordnance Regs "theory"? If you read the above, it pretty plainly says that cordite heavily erodes the throat and quickly makes firing N.C. ammo in it inaccurate.

4. Trials have proved that even if only a few rounds of Cordite ammunition are fired from an "N.C." barrel, the ensuing accuracy life when N.C. is subsequently fired is reduced considerably. The occasional and restricted use of N.C. in a "Cordite" barrel will however, have little effect on its ensuing accuracy life for Cordite, although naturally the fire of N.C. will not be very accurate.

^there's your explanation. Shooting only cordite will be fine accuracy-wise, but if you reload and/or shoot non-cordite ammo, your accuracy will suffer. I see no reason to shoot cordite for this reason as the days of plentiful cordite surplus is far behind us. And you conveniently ignore the many Enfields that have had their throats shot out, barrels replaced, or scrapped entirely.

 

[BFMIN]

answer my question, please. IF its true why "
But we're talking multiple Thousands of rounds & as I stated this bore has already seen cordite, as has my BSA 1914 SMLE & My Savage No4 Mk1*. Both shoot within spec.
As a a counterpoint I present all the accurate Long Lees, Lee Metfords, LLEs, CLLE's, SMLE no 1MkIII ( & MkIII*), No4 Mk1, Mk2, Mk 1/2, Mk1/3, & everything else firing the Mk 2~7 .303 British round for over 100 years, most of which can still group to meet or beat Factory spec.
Explain that away."

 

[BFMIN]

As an FYII followup to the “Bore Killing” Mk8(Z).
Its a bit long as the technical stuff tends to be, but IMO worth the time taken to peruse it.

I couldn’t resist doing a little research on the Mk8(z) & MkVII ammunition & bore wear. Call it a character failure, but I like to do research, not simply parrot old doctrine.
Nothing against the writer, he’s good, but time sometimes reveals things that weren’t known at the time & that can lead to changes. I've highlighted the most relevant passage.

There were great variations in the assorted Mk 8z, here's a comparison with test data I discovered a while back when I obtained some Prvi "Mk8z".
.303 British, Mk VII ball & the “bore-killing hot Mk 8Z”

"So, here I was somewhat bored, surfing the various Enfield forums & I got to wonder about some ammo I had acquired. It was headstamped as Prvi Partizan (“nny-85” headstamped) Mk 8Z in .303 British. This is the “bore killing uber hot machine gun ammo, never to be used in rifles”. What was this stuff in reality?

Being me I pulled down a couple of dinged up rounds & did some testing & guess what I found? There’s more than one kind of “Mk8Z” & it differs quite a bit by country/manufacturer. A bit more research & I worked out that a lot of us are actually making & shooting modernized Mk8Z-type ammo & our bores are doing just fine.

OK let’s start at the beginning. What’s “real Mk VII” in detail?

In 1910 the British Ministry of Defense, part of the War Office, “sealed” the design & nomenclature of British Mk VII service ball ammunition. “Sealed,” means no changes, ever the spec is cast in stone & can’t be un-done, or modified without some serious pre-planning. It’ll probably become a new Model, Mark, or at the least get a (*) added to denote it’s different from “regular issue stuff”. Such was the case with the MkVII (or Mk 7, after 1945) ball ammo. It was a 174 Gr FMJ flat-based bullet with a “tenite, (cellulose plastic)” fiber or aluminum internal core at the front & a lead core behind that. B.C. was 0.467. Propellant was charge weight that could vary from 35 to 38 grains, averaging 36.5 grains of “Cordite”, (the standard 58% Nitro-glycerin, 37% Nitro-cellulose and 5% Mineral Jelly) propellant of most British ammunition. Muzzle velocity was 2440 FPS & pressure was 52,900 PSI. (Current SAAMI specs are lower at 49,000 PSI, but that was yet to come, as were modern measuring techniques for pressure). 45000CUP was the actual measurement used at the time. There was a card disc over the propellant used as an anti-ablation shield to reduce flame-cutting erosion of the bore.

So. What’s different about a MkVII (7) or Mk VIII (8), or Mk 8(z) round, designed for use in the Vickers machine gun for long range shooting?

A few things actually & there are several variants on the basic Mk8 design. It was never “sealed” like the Mk VII (7) was, so changes were easy.

The biggest difference was the bullet. The ballistically inefficient Mk VII round with its drag inducing flat base was replaced by a couple of different boat tail designs. Boat tails reduce drag, increase the BC of the bullet & allow it to fly on a flatter trajectory, increasing the effective range over a similar flat base one. The Mk 8 bullet was a 175~190-grain boat tailed, streamlined, steel jacketed bullet. Initially the boat tail was not full diameter but “stepped” with a flat annular base with the boat tail starting at a slightly reduced diameter. This was done in an attempt to stop rifling erosion, resulting in blow by & reduced accuracy. Because of its design the Mk 8 bullet was found to have a different issue, stiffness. Compared to the relatively soft Mk 7 it didn’t obdurate as well, so conforming to the rifling, particularly in worn, or cordite-eroded 2-groove barrels, was less efficient. At that point the stepped boat tail was dropped in favor of a “normal” full diameter boat tail design.

Slightly more “neonite”** propellant was added, giving a muzzle velocity of 2550 ft/s (780 m/s) and somewhat better ballistics. Chamber pressure was higher, at 40,000–42,000 lbf/in² (about 280 MPa). These were the “Hotter, Vickers machine gun only” ammunition that started the whole debate off. Neonite** incidentally is NOT cordite, nor a derivative of it. The closest current propellant to it is IMR 3031, a nitro-cellulose powder!

But there wasn’t anywhere near the standardization that existed with Mk VII ammo because of the “sealed changes” in design!

So is ALL Mk8Z a bore killer, or are there variations that are less damaging?

Some surprising things I’ve discovered about Mk8Z ammo. It varied way, way more than thought, look at these pull down figures!

Mark VIIIz Spec - bullet 175 grns +-2 grns, propellant 37 to 40 grains NC. Velocity 2,550 fps.
Spennymoor 1941 - Bullet 175.0 grns, prop.38.0 grns
RG 1944 - bullet 176 grns, prop. 36.5 grns
Spennymoor 1944 - bullet 174.5 grns, prop. 37.5 grns
Spennymoor Ballistic Standard 1944 - bullet 174 grns, prop 36.5 grns
RG 1945 - bullet 174.5 grns, prop.36.75 grns
RG 1948 - bullet 177 grns, prop 37.0 grns
IVI 1985 - bullet 175 grns, prop 37.5 grns
(The ballistics of the IVI Mark 8z was arranged to be between the Mark 7 and Mark 8z suitable for the No.4 rifle with 300 yard battle sight).

I weighed & measured the COAL of a S/A "R1M3Z ~ A80" (which is Mk VII spec, including the filler-tipped 174 Gr bullet), & the "nny-85" ball round, here’s the results for loaded, unfired rounds:
R1M3Z
Length = 3.0285"
Weight = 408.7 Gr.
Powder charge was 39.6 Gr of a stick powder similar in appearance to IMR 4895, but there’s no way to tell what exactly it was. The bullet was a FMJ FB 174 grain MKVII.

nhy-85 Mk8Z
Length = 3.053"
Weight = 405.5 Gr
Powder charge was 38.4 Gr of a stick powder similar in appearance to IMR 4895, but there’s no way to tell what exactly it was either. The bullet was a boat tailed 190 gr FMJ.

Now for the big surprise! The Prvi Partizan MkVIII(z) variant is slower than South African R1M3Z. It also has less recoil (big surprise there.)
Chronograph results.
R1M3Z 174Gr ball
Average = 2525
Low = 2497
High = 2592
Prvi Mk8Z 190 Gr ball BT
Average = 2359
Low = 2335
High = 2359
All velocities instrumental @ 10' from a standard No4 Mk2 barrel.
The SA R1M3Z is about on the ball for weight. Military .303 weights are 174gr bullet, 195 gr case and about 35-40 gr prop. With 38gr prop and a 190 gr bullet it suggests the PPU has a case of about 177 gr.

For comparison purposes, case weights & thickness vary a lot so its misleading to just weigh a loaded round to see whats insde it:
empty (fired case) weights
S/AR1M3Z = 201.4 Gr
nny = 178.2 Gr
R-P commercial = 160.9gr
PPU = 173.3gr
HXP = 186.7
RG-50 = 185.7 Gr.
(This is actual British-made Mk VII ball, so I include it as a reference for weights.)

So all Mk8Z is not created equal at all!

Bullets can vary in weight, velocities likewise & several different propellants are used. The reason cited for the “Machine gun only” restriction was because of the combined effects of cordite erosion (amazing as there was no cordite in them) & boat tail bullet shape & construction. Not one cause, but a combination of things. Flame temperature, bullet construction & bullet shape all combining to have a negative & damaging effect. Where does that leave us today? There have been improvements in powders, better designs of bullets & so on. Can we make, or use something with the better performance of the “Long Range Mk VIII(z)” or are we stuck with the Mk VII including it’s flat base limitations?

Well whats a” regular, average normal” Mk8(z)?
Using the widely varying components & velocities of the different versions of the round, somewhere between a 175gr & a 190 gr FMJ BT with a BC of between 0.470 0.485 & bullet doing somewhere between 2550FPS at the muzzle & 2359 FPS at 10 feet with somewhere below 42000PSI of chamber pressure.

Here’s my suggestion. We not only can do a better MKVII(z) but we have been dong it for quite a while with a great deal of success & no horrible barrel damage.

How?

Simple!
Use the Hornady .311” 174 gr Matchking, or the similar Hornady #3131 .3150" 174 Gr FMJ-BT!

Propel it with 41.6 gr of IMR 4895 for 2450 FPS, or 43.0 gr of .IMR 4320, for 2470. None of these exceed the lower SAAMI pressures of 49,000 PSI. & The Sierra Match King’s BC of 0.499 or the Hornady’s 0.470 & better construction will allow full upset for full obduration of the bore completely eliminating the blow by problems of the old Mk VIII bullets, while gaining the trajectory because of its better design & boat tailed shape. The lower flame temps of modern powders should help as well. In fact they have been doing just that at matches for years, we simply didn’t recognize it!

**”Neonite” is a nitrocellulose propellant, as referenced in both 1920's "Dictionary of Explosives" as well as the 1944 edition of the "Textbook of Ammunition".
Neonite loaded ammunition, both pistol and machine-gun, is listed with the 'z' designation, the chopped cordite loads for pistol ammunition being clearly differentiated from it".

 

[Doco Overboard]

As an FYII followup to the “Bore Killing” Mk8(Z).
Its a bit long as the technical stuff tends to be, but IMO worth the time taken to peruse it.

I couldn’t resist doing a little research on the Mk8(z) & MkVII ammunition & bore wear. Call it a character failure, but I like to do research, not simply parrot old doctrine.
Nothing against the writer, he’s good, but time sometimes reveals things that weren’t known at the time & that can lead to changes. I've highlighted the most relevant passage.

There were great variations in the assorted Mk 8z, here's a comparison with test data I discovered a while back when I obtained some Prvi "Mk8z".
.303 British, Mk VII ball & the “bore-killing hot Mk 8Z”

"So, here I was somewhat bored, surfing the various Enfield forums & I got to wonder about some ammo I had acquired. It was headstamped as Prvi Partizan (“nny-85” headstamped) Mk 8Z in .303 British. This is the “bore killing uber hot machine gun ammo, never to be used in rifles”. What was this stuff in reality?

Being me I pulled down a couple of dinged up rounds & did some testing & guess what I found? There’s more than one kind of “Mk8Z” & it differs quite a bit by country/manufacturer. A bit more research & I worked out that a lot of us are actually making & shooting modernized Mk8Z-type ammo & our bores are doing just fine.

OK let’s start at the beginning. What’s “real Mk VII” in detail?

In 1910 the British Ministry of Defense, part of the War Office, “sealed” the design & nomenclature of British Mk VII service ball ammunition. “Sealed,” means no changes, ever the spec is cast in stone & can’t be un-done, or modified without some serious pre-planning. It’ll probably become a new Model, Mark, or at the least get a (*) added to denote it’s different from “regular issue stuff”. Such was the case with the MkVII (or Mk 7, after 1945) ball ammo. It was a 174 Gr FMJ flat-based bullet with a “tenite, (cellulose plastic)” fiber or aluminum internal core at the front & a lead core behind that. B.C. was 0.467. Propellant was charge weight that could vary from 35 to 38 grains, averaging 36.5 grains of “Cordite”, (the standard 58% Nitro-glycerin, 37% Nitro-cellulose and 5% Mineral Jelly) propellant of most British ammunition. Muzzle velocity was 2440 FPS & pressure was 52,900 PSI. (Current SAAMI specs are lower at 49,000 PSI, but that was yet to come, as were modern measuring techniques for pressure). 45000CUP was the actual measurement used at the time. There was a card disc over the propellant used as an anti-ablation shield to reduce flame-cutting erosion of the bore.

So. What’s different about a MkVII (7) or Mk VIII (8), or Mk 8(z) round, designed for use in the Vickers machine gun for long range shooting?

A few things actually & there are several variants on the basic Mk8 design. It was never “sealed” like the Mk VII (7) was, so changes were easy.

The biggest difference was the bullet. The ballistically inefficient Mk VII round with its drag inducing flat base was replaced by a couple of different boat tail designs. Boat tails reduce drag, increase the BC of the bullet & allow it to fly on a flatter trajectory, increasing the effective range over a similar flat base one. The Mk 8 bullet was a 175~190-grain boat tailed, streamlined, steel jacketed bullet. Initially the boat tail was not full diameter but “stepped” with a flat annular base with the boat tail starting at a slightly reduced diameter. This was done in an attempt to stop rifling erosion, resulting in blow by & reduced accuracy. Because of its design the Mk 8 bullet was found to have a different issue, stiffness. Compared to the relatively soft Mk 7 it didn’t obdurate as well, so conforming to the rifling, particularly in worn, or cordite-eroded 2-groove barrels, was less efficient. At that point the stepped boat tail was dropped in favor of a “normal” full diameter boat tail design.

Slightly more “neonite”** propellant was added, giving a muzzle velocity of 2550 ft/s (780 m/s) and somewhat better ballistics. Chamber pressure was higher, at 40,000–42,000 lbf/in² (about 280 MPa). These were the “Hotter, Vickers machine gun only” ammunition that started the whole debate off. Neonite** incidentally is NOT cordite, nor a derivative of it. The closest current propellant to it is IMR 3031, a nitro-cellulose powder!

But there wasn’t anywhere near the standardization that existed with Mk VII ammo because of the “sealed changes” in design!

So is ALL Mk8Z a bore killer, or are there variations that are less damaging?

Some surprising things I’ve discovered about Mk8Z ammo. It varied way, way more than thought, look at these pull down figures!

Mark VIIIz Spec - bullet 175 grns +-2 grns, propellant 37 to 40 grains NC. Velocity 2,550 fps.
Spennymoor 1941 - Bullet 175.0 grns, prop.38.0 grns
RG 1944 - bullet 176 grns, prop. 36.5 grns
Spennymoor 1944 - bullet 174.5 grns, prop. 37.5 grns
Spennymoor Ballistic Standard 1944 - bullet 174 grns, prop 36.5 grns
RG 1945 - bullet 174.5 grns, prop.36.75 grns
RG 1948 - bullet 177 grns, prop 37.0 grns
IVI 1985 - bullet 175 grns, prop 37.5 grns
(The ballistics of the IVI Mark 8z was arranged to be between the Mark 7 and Mark 8z suitable for the No.4 rifle with 300 yard battle sight).

I weighed & measured the COAL of a S/A "R1M3Z ~ A80" (which is Mk VII spec, including the filler-tipped 174 Gr bullet), & the "nny-85" ball round, here’s the results for loaded, unfired rounds:
R1M3Z
Length = 3.0285"
Weight = 408.7 Gr.
Powder charge was 39.6 Gr of a stick powder similar in appearance to IMR 4895, but there’s no way to tell what exactly it was. The bullet was a FMJ FB 174 grain MKVII.

nhy-85 Mk8Z
Length = 3.053"
Weight = 405.5 Gr
Powder charge was 38.4 Gr of a stick powder similar in appearance to IMR 4895, but there’s no way to tell what exactly it was either. The bullet was a boat tailed 190 gr FMJ.

Now for the big surprise! The Prvi Partizan MkVIII(z) variant is slower than South African R1M3Z. It also has less recoil (big surprise there.)
Chronograph results.
R1M3Z 174Gr ball
Average = 2525
Low = 2497
High = 2592
Prvi Mk8Z 190 Gr ball BT
Average = 2359
Low = 2335
High = 2359
All velocities instrumental @ 10' from a standard No4 Mk2 barrel.
The SA R1M3Z is about on the ball for weight. Military .303 weights are 174gr bullet, 195 gr case and about 35-40 gr prop. With 38gr prop and a 190 gr bullet it suggests the PPU has a case of about 177 gr.

For comparison purposes, case weights & thickness vary a lot so its misleading to just weigh a loaded round to see whats insde it:
empty (fired case) weights
S/AR1M3Z = 201.4 Gr
nny = 178.2 Gr
R-P commercial = 160.9gr
PPU = 173.3gr
HXP = 186.7
RG-50 = 185.7 Gr.
(This is actual British-made Mk VII ball, so I include it as a reference for weights.)

So all Mk8Z is not created equal at all!

Bullets can vary in weight, velocities likewise & several different propellants are used. The reason cited for the “Machine gun only” restriction was because of the combined effects of cordite erosion (amazing as there was no cordite in them) & boat tail bullet shape & construction. Not one cause, but a combination of things. Flame temperature, bullet construction & bullet shape all combining to have a negative & damaging effect. Where does that leave us today? There have been improvements in powders, better designs of bullets & so on. Can we make, or use something with the better performance of the “Long Range Mk VIII(z)” or are we stuck with the Mk VII including it’s flat base limitations?

Well whats a” regular, average normal” Mk8(z)?
Using the widely varying components & velocities of the different versions of the round, somewhere between a 175gr & a 190 gr FMJ BT with a BC of between 0.470 0.485 & bullet doing somewhere between 2550FPS at the muzzle & 2359 FPS at 10 feet with somewhere below 42000PSI of chamber pressure.

Here’s my suggestion. We not only can do a better MKVII(z) but we have been dong it for quite a while with a great deal of success & no horrible barrel damage.

How?

Simple!
Use the Hornady .311” 174 gr Matchking, or the similar Hornady #3131 .3150" 174 Gr FMJ-BT!

Propel it with 41.6 gr of IMR 4895 for 2450 FPS, or 43.0 gr of .IMR 4320, for 2470. None of these exceed the lower SAAMI pressures of 49,000 PSI. & The Sierra Match King’s BC of 0.499 or the Hornady’s 0.470 & better construction will allow full upset for full obduration of the bore completely eliminating the blow by problems of the old Mk VIII bullets, while gaining the trajectory because of its better design & boat tailed shape. The lower flame temps of modern powders should help as well. In fact they have been doing just that at matches for years, we simply didn’t recognize it!

**”Neonite” is a nitrocellulose propellant, as referenced in both 1920's "Dictionary of Explosives" as well as the 1944 edition of the "Textbook of Ammunition".
Neonite loaded ammunition, both pistol and machine-gun, is listed with the 'z' designation, the chopped cordite loads for pistol ammunition being clearly differentiated from it".

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Thanks BFMIN.
Just like what we talked about at the range the other day as Im sure you recall, but much more succinctly presented on your behalf as usual.
I don't have the patience anymore when I can just glean the information from my library and sometimes it is hard to decipher such a prolific history associated for both rifle and ammo.
All I really have is the memory of blowing through scads of that ammo when it was in abundance to me and the possibility of a few of those wonderful cello wrapped packets with the green printed writing in the bottom of an ammo locker here at Fort Doco.

 

[Dave91]

I bought a wash bottle for cleaning after shooting corrosive stuff:

I originally bought it for flushing out the bore of my flintlock rifle through the flash hole, but it works great for my other rifles too. You can get that nozzle in the nooks and crannies.

 

[Doco Overboard]

That’s a good idea.
Ordinarily I just carefully spill water into the breech and patch it out.

 

[BFMIN]

I just re-built my original long neck filter funnel. I'm good for next time!
Maybe the galvanized goose neck will go in sideways or something!
Those heavy RNSP bullets we were discussing are genuine "Woodliegh" 215Gr .311 FB. I dont have an exact count but its most of a 100 Ct box so I'd guess about 80 or so.
The second box I'd approach with great good caution regarding the previous post!
They're Lapua 200Gr FMJ, BUT they're all rebated boat tails! Again most of a box I'm guesisng by weight 75~80 Pc count. They also mic to .3105"