.303 MkVIIz

PerversPépère

PerversPépère

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Hello!
I have been given four sealed boxes of 1948 and 1951 canadian manufacture Mk VIIz .303 military ammunition.
It is BOXER PRIMED.
It fed, shot and extracted very well in my LongBranch but looking for that round's specs on the web, I just found this:

"In 1938 the .303 Mark VIIIZ round was approved to obtain greater effective range from the Vickers Medium Machine Gun. This round had a nitro-cellulose powder charge with a 175 grain boat tailed, streamline, jacketed bullet having a muzzle velocity of 2550 feet per second. Chamber pressure however was higher at 20 - 21 tons per square inch compared to the 19.5 tons per square inch of the Mark VII round."

I stopped using it immediately, even though it fed and extracted smoothly.
Do you think I should relegate it to machine-gun feeding?:confused:
PP.
 
What is the head stamp. Never saw any 1948 date Cdn MkVIIz and 1951 was Berdan primed by Dominion Arsenal. VIIz was the same as VII except for the powder nitrocellulose vs cordite.
 
The .303 Mark VIIIZ is fabulous stuff. The cases usually had "Not for use in synchronised guns" stenciled on them. Works just fine out of a rifle. The best .303 ammo I've ever shot was .303 Mark VIIIZ made in 1944. Out of a No. 4 rifle.
 
Great!
So I guess I can shoot these too in my 1910 Ross which is a lot more stouter than a No.1MkIV action.:D
I know the Ross has a liking for any boat-tailed bullet in the 174gr. vicinity.
I have two 48 round packs of 1944 ammo marked "CARTRIDGES .303 INCH D.I. Mk VIIz I.G. CANADA" and the other pair is 1951 manufacture, marked "48 CARTRIDGES .303 INCH Mk 7z" and below is a capital "C" with an arrow inside over the letters C.I.A.

In the boxes, at least the one I shot, there is a paper separator between each round.
Both style of rounds have a visible annealing mark at the neck and shoulder, more so on the 1944 round.
The 1944 round has a 3 sector crimp at half-neck;bullet is silvery.
The 1951 has a knurled groove on the bullet shank and the mouth is crimped in it. Bullet is brass-coloured.
The 1951 headstamp is D.A.C (with arrow) then 51, then 7z. at thirds.
The 1944 headstamp is 1944 and DI Z on the opposite side;
Both rounds have an annulus crimp around the primer.
I have yet to shoot the 1951 rounds so I don't know if that ammo is Berdan or Boxer primed but the 1944 is Boxer primed, even if it is hard to get the primer out, due to the annulus crimp. Best way is with a punch and a base like in the Lee Loader. I guess an universal decapping die could do as well.
Come to think of it, the primer looks larger on the 1951, so I guess this one could be a Berdan primed round.
PP.
 
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The DI ammuntion is excellent, non-corrosive, Boxer primed. The '51 DA probably has a large (1/4") diameter copper coloured Berdan primer. I suspect it may be corrosive. Good ammunition, though.
 
The reason MkVIIIz is marked for machine guns is because it uses a boat tailed bullet. Cordite causes throat erosion in rifles and boat tails don't seem to shoot very well in those barrels because of that. However changing the barrel on a Vickers for a fresh one is only a matter of a minute or two.
In a relatively little worn barrel it's no problem
 
I've got some of the MK 8Z stuff, South African 1980 manufacture, don't know if it's non-corrosive but it is berdan primed. Don't know if it was meant for use in the SMLE or the Vickers or maybe it was for use in the Bren? Sorry didn't mean to hijack. Haven't seen any surplus in Nova Scotia for quite a long time, :confused: maybe I'm looking in the wrong place? Regards FT. :)
 
Corrosive

tiriaq said:
The DI ammuntion is excellent, non-corrosive, Boxer primed. The '51 DA probably has a large (1/4") diameter copper coloured Berdan primer. I suspect it may be corrosive. Good ammunition, though.
Click to expand...

This was my guess, too. I better play it safe and do the "old funnel and hot water trick".
PP.
 
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Cordite?

John Sukey said:
The reason MkVIIIz is marked for machine guns is because it uses a boat tailed bullet. Cordite causes throat erosion in rifles and boat tails don't seem to shoot very well in those barrels because of that. However changing the barrel on a Vickers for a fresh one is only a matter of a minute or two.
In a relatively little worn barrel it's no problem
Click to expand...

Did the DI ammo made in 1944 still make use of Cordite? I though Cordite was dropped from .303 rounds much earlier.
Guess I'll have to break one down just to see if it still holds the "darned spaghetti"...:confused:
PP.
 
Cordite was loaded by Dominion Arsenal in .303" until the early 50s in Canada, the early 60s in Britain and c1980 in India. If a .303" ctg has a "z" in the headstamp it is loaded with nitrocellulose.
All DI .303" ammo was loaded with nitrocellulose very similar in appearance to IMR 3031, 41 gr IIRC.
DI ammo was all noncorrosive using the Dominion commercial primer.
 
Okay, we have two separate problems...... difference between Mark VII (or 7 if you prefer) and Mark VIII (or 8 if you prefer)........ and the difference between Cordite and Type Z powder.

The ammo plants mixed things up from lot to lot at times, and you can find Mark 7, Mark 7Z, Mark 8, Mark 8Z........ and Mark VIIZ, Mark VII, Mark VIIIZ and Mark VIII. Arrrrrrrrrrrrrrrgh!

The MARK gave you the specification to which the ammo was loaded. All Mark VII or 7 ammo was loaded to give the 174-grain FLAT-based bullet 2440 ft/sec at the muzzle and a nominal pressure of about 18-1/2 Long Tons of pressure. It didn't matter if the ammo was Z or Cordite, it performed the same. Cordite was usually loaded with the big CORROSIVE Berdan primer, but they often loaded the Type Z powder (Officially Nobel Neonite, very, very similar to IMR 4895) with NONcorrosibe Boxer primers. All Defence Industries (DI Z) ammunition was NONcorrosive, NONmercuric and loaded with this Type Z powder. MOST Dominion Arsenals ammo was loaded with Cordite and the big bad nastyugly corrosive/mercuric primer.

Mark VIII (or 8) ammunition loaded a 174-grain (officially) BOAT-TAILED bullet at 2550 ft/sec muzzle velocity and a working pressure supposedly about 19-1/2 British Long Tons, or 2240 psi heavier. Mark VIII (and Mark 8) ammo also was loaded with Cordite or with the same Nobel-neonite-IMR4895-clone powder.

In a good Number 4 in good condition they should all be safe to shoot. The Army reproofed a whack of Number 4 rifles to shoot the higher-pressure Mark 8 ammo, and they held together okay.

As far as your DI ammo is concerned, it likely was the very best .303 ammunition of World War Two and it is definitely some of the best reloading brass ever made anywhere.

Have fun.
 
Hi

Gee, I figured this would be answered by now...

While the gent above me had the weights of the two bullets, the big difference is that the Mk VII has either an aluminum or fiber section in the front of the bullet under the jacket. This made the slug easy to destabilize, in other words it made a mess when it hit the enemy. Usually, it was rifle ammo. The VIII was kept for machine guns because it had better range.

Sticker
 
I was told by someone on another forum the reason for the MKVII was to move the center of gravity of the bullet to the rear while it was in the air which made it more accurate like the hollow point sniping bullet the US army is using, maybe the fishhook action was a bonus, possibly not just an afterthought if you think about the way things were done back then. Regards FT.
 
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You mentioned MkVIIz in the first paragraph and then MKVIIIZ in the second. I just assumed you intended to say MkVIIIZ since you said you immediatly stopped shooting it.
In any case MkVIIz is EXACTLY the same as MkVII except for the use of smokeless powder instead of cordite.
 
John Sukey said:
You mentioned MkVIIz in the first paragraph and then MKVIIIZ in the second. I just assumed you intended to say MkVIIIZ since you said you immediatly stopped shooting it.
In any case MkVIIz is EXACTLY the same as MkVII except for the use of smokeless powder instead of cordite.
Click to expand...
Yes; I quoted a text found on the net about those cartridges. I stopped using them because I figured that "z" was the indicator for higher pressure rounds but it seems after all that it is only the indicator of a different powder and not necessarily higher pressure load.
Now, all is good and clear. Thanks John!
BTW guys, nice bit of knowledge and history there!
PP.:)
 
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