.303 Mk 8Z Rounds

Isn't the point in the documentation that it was not a problem due to VII cordite wear itself, but rather that 8z nitro wear did not give any gradual sign of range/accuracy drop off, and thus had to be given an arbitrary round limit per barrel (10,000 rnds)?

The MkVII wear in the MG barrel did not itself create a hazard, but by mixing round type and wear it thus negated the safety margin in the "10,000 rnd" limit for the 8z use, by upsetting the "round count".

IIRC MkVII was safe to use in MGs for much greater round count (typically 15-20k, depending upon rates) because the effect of wear on range/accuracy was a much more gradual process and easily observed by the firer.

Thus 8z was a better long range round, but it brought with it the hazard of abrupt change in performance once past a certain bore wear point.



IIRC the "burns the bore lead" aspect actually ended as soon as the original cordite mix was changed. Subsequent wear pattern differences between cordite and nitro loads are probably more to do with bullet shape and the way they set up into the rifling lead on firing.

The evidence from the MG side is that total bore wear is roughly the same for cordite and nitro, but that it is just distributed differently - cordite towards the rear, nitro towards the front.

Presumably the lower contact surface of the 8z boat tail is less of a "plug" at the rifling lead than the VII flat base bullet, and thus cause slightly less friction wear at that point.

Interestingly, there is one theoretical way to test this, which would be to fire a new rifle to burn out using VIIz ammunition - i.e. nitro with a flat base bullet. Sadly, there is probably not enough VIIz remaining to run the test; its the rarest type of ammo to find these days (all those pesky cadets shooting it off in the 80s!).
1593269274134.png

1593269116956.png


I had a No.4 barrel sectioned back in the day that had horrific throat wear - it was "washed" like a river-bed in the throat, which left grooves. Never seen that with NC propellant. Stupidly, it got thrown out in a house move in 2003... Wish I still had it.
 

HE117

LE
View attachment 485361
View attachment 485360

I had a No.4 barrel sectioned back in the day that had horrific throat wear - it was "washed" like a river-bed in the throat, which left grooves. Never seen that with NC propellant. Stupidly, it got thrown out in a house move in 2003... Wish I still had it.
I remember reading that.. is it from one of the Inf Trg pams?

Breaking down link is still illegal.. but they still do it to get tracer..!
 
I remember reading that.. is it from one of the Inf Trg pams?

Breaking down link is still illegal.. but they still do it to get tracer..!
It's from the 1945 edition of Pamphlet 11

1593272077878.png
 

HE117

LE
It's from the 1945 edition of Pamphlet 11

View attachment 485371
My God.. RAOS Pam 11!

I haven't seen a copy of that for donkeys years.. Most of it got split up into other documents in the 60s, and I think Pam 11 became Ammunition and Explosives Regulations when ammunition management was devolved to Chief Inspector Land Service Ammunition.

The only RAOS I can recall covered packaging and tentage!
 
My God.. RAOS Pam 11!

I haven't seen a copy of that for donkeys years.. Most of it got split up into other documents in the 60s, and I think Pam 11 became Ammunition and Explosives Regulations when ammunition management was devolved to Chief Inspector Land Service Ammunition.

The only RAOS I can recall covered packaging and tentage!
I'll e-mail you a copy :)
 

HE117

LE
Is there then a DS solution ?

I am wary of using the Mk8Z .303 on such a Gucci rile - albeit only having 40 rounds.

At the moment my thoughts are wandering towards the idea of breaking down the Mk8Z ammunition and re-loading with an appropriate charge of a modern propellant for a 174 grain FMJ flat based bullet which is what I am loading my .303 brass with anyway.

Then, after firing, giving the rifle the mother of all cleans in order to reduce the ill effects caused by probably/possibly corrosive primers.

Seems like a plan, but I fear "The Purple Caped One" may be sitting on my shoulder and whispering, whispering, whispering.
 
Is there then a DS solution ?

I am wary of using the Mk8Z .303 on such a Gucci rile - albeit only having 40 rounds.

At the moment my thoughts are wandering towards the idea of breaking down the Mk8Z ammunition and re-loading with an appropriate charge of a modern propellant for a 174 grain FMJ flat based bullet which is what I am loading my .303 brass with anyway.

Then, after firing, giving the rifle the mother of all cleans in order to reduce the ill effects caused by probably/possibly corrosive primers.

Seems like a plan, but I fear "The Purple Caped One" may be sitting on my shoulder and whispering, whispering, whispering.
Loads of that stuff was fired without incident through all types of Enfield when it was common on the market in the early 00's. I shouldn't worry about it (I fired a 250-rd box or 2).
 

HE117

LE
Is there then a DS solution ?

I am wary of using the Mk8Z .303 on such a Gucci rile - albeit only having 40 rounds.

At the moment my thoughts are wandering towards the idea of breaking down the Mk8Z ammunition and re-loading with an appropriate charge of a modern propellant for a 174 grain FMJ flat based bullet which is what I am loading my .303 brass with anyway.

Then, after firing, giving the rifle the mother of all cleans in order to reduce the ill effects caused by probably/possibly corrosive primers.

Seems like a plan, but I fear "The Purple Caped One" may be sitting on my shoulder and whispering, whispering, whispering.
You will be fine mate! There is no risk to the gun firing Mk8 out of an SMLE and the gun was designed to fire corrosive primers... That's why it is rear locking so you can get at the breech to clean it..

Just give the gun a good clean afterwards..!
 
Fairynuff, off to the big paddock to do some zeroing and grouping, it'll be interesting to see what the results of three different natures of ammunition will make.

Shall set sights at 200 with windage set to dead centre - shall be shooting from 100, prone supported.
 

HE117

LE
Shot Over!
 

Bad Smell

Clanker
After reading this thread I needed some clarification, so do apologise to the above members who know far more about this subject than I. I wanted to clarify between MkVII and MkVIII cartridges and the addition of the letter Z. The above information does clarify the differences that but left me a little perplexed regarding the "Z".

The only book I have regarding .303 ammunition is Barry Temple's 1995 World War 1 Armaments and the .303 British Cartridges. Unfortunately I don't have his 1986 book on the .303 Cartridge. Thought I would share for the other dumb arses like me, so I'll quote from Chapter One:

Since 1893 the official British service propellant for certain ordnance and SA cartridges had been cordite, and it remained so until the onset of WW1, when to supplement home production, it was decided to order large quantities of .303-inch ball ammunition from manufacturers in the USA.

Although obviously having to comply basically with the standard specifications for the then current Mark VII ball, the resulting American ammunition incorporated minor variations from it, because of different components and procedures used there. One major difference was in the propellant, as US factories did not make cordite, but for SA cartridges utilised a nitrocellulose powder known as Du Pont IMR16 (ie, Improved Military Rifle No.16).

The American contract .303-inch cartridges, some 600 million or so rounds, were considered quite satisfactory, so, as the war progressed, when the British ordnance factories became incapable of coping with the enormous demands for cordite - especially created by the ever-increasing use of artillery on the Western Front - it was decided to obtain supplies of the American powder and load home produced .303-inch ammunition with it, and so reduce the demand on cordite production.


I can now sleep better at night knowing this.
 

HE117

LE
It's fairly simple...

UK ammunition described under the old "Mark" system added a "z" to any ammunition not filled with cordite...

Cartridge, Ball, .303 MkVII - Ball cartridge loaded with the flat based spitzer mark 7 bullet and a cordite charge

Cartridge, Ball, .303 MkVIIz - Ball cartridge loaded with the flat based spitzer mark 7 bullet but with a charge that was not cordite. Usually NC powder or equivalent. You could usually work out what propellant was used from the filling factory code.

Cartridge, Ball, .303 MkVIII - Ball cartridge loaded with the boat tail spitzer mark 8 bullet and a cordite charge.

All this went when we went to the NATO terminology and L - A designations, such as:

Round 7.62 mm Ball Sniper L42A1 155 Grain

Which is the current 7.62 sniper round.. the L42A1 designation is not for the rifle, but is the designation of the round. There are L42A1, A2, and A3 variants, depending on the primer used. The weight is given in the designation as the round deviates from the NATO standard 7.62 round which has a 9.33g/144gn bullet.

The reason for all this is that although the standard rifle was safe to shoot all the variations of ammunition there would probably be a performance difference between types. Ammunition of the same type, but different lots was designed to give the same performance for most applications. In other words there should not be a need to re-zero rifles between lots unless you were going for top end accuracy. Switching from cordite to NC however probably needed a check zero, even for line infantry, and hence it was sensible to mark up the ammunition so the user could tell the difference. Sniper ammunition is made to much higher tolerances (... although opinion s vary!) but it was obviously thought changing the primer was important enough to the user to change the marking on the round...

Cabish?
 
Last edited:

HE117

LE

4(T)

LE
FWIW, this is MkVIIIz's brother.

VIIIz derived from the 1930s .303" magnum (case) and "streamline" (bullet) programme - ammo jointly developed by Kynoch, Bisley and the Army for match and long range shooting. The last pre-war iteration, where the magnum case was dropped for a .303 case, became VIIIz.

Post war, three or four further iterations (tiny changes to the step in the boat tail bullet) served as Kynoch's match ammunition for Bisley and the Olympics up until the change to 7.62mm in the 1960s.


 
It's fairly simple...

UK ammunition described under the old "Mark" system added a "z" to any ammunition not filled with cordite...

Cartridge, Ball, .303 MkVII - Ball cartridge loaded with the flat based spitzer mark 7 bullet and a cordite charge

Cartridge, Ball, .303 MkVIIz - Ball cartridge loaded with the flat based spitzer mark 7 bullet but with a charge that was not cordite. Usually NC powder or equivalent. You could usually work out what propellant was used from the filling factory code.

Cartridge, Ball, .303 MkVIII - Ball cartridge loaded with the boat tail spitzer mark 8 bullet and a cordite charge.

All this went when we went to the NATO terminology and L - A designations, such as:

Round 7.62 mm Ball Sniper L42A1 155 Grain

Which is the current 7.62 sniper round.. the L42A1 designation is not for the rifle, but is the designation of the round. There are L42A1, A2, and A3 variants, depending on the primer used. The weight is given in the designation as the round deviates from the NATO standard 7.62 round which has a 9.33g/144gn bullet.

The reason for all this is that although the standard rifle was safe to shoot all the variations of ammunition there would probably be a performance difference between types. Ammunition of the same type, but different lots was designed to give the same performance for most applications. In other words there should not be a need to re-zero rifles between lots unless you were going for top end accuracy. Switching from cordite to NC however probably needed a check zero, even for line infantry, and hence it was sensible to mark up the ammunition so the user could tell the difference. Sniper ammunition is made to much higher tolerances (... although opinion s vary!) but it was obviously thought changing the primer was important enough to the user to change the marking on the round...

Cabish?
IIRC there was never a Cordite-loaded Mk.VIII. It was all NC-loaded hence VIIIz / 8z
 

HE117

LE
IIRC there was never a Cordite-loaded Mk.VIII. It was all NC-loaded hence VIIIz / 8z
You are of course correct... I had my "naming and designation" head on when I wrote that.. In my defence. if there HAD been a cordite loaded MkVIII that's what it would have been called!
 

Latest Threads

Top