Replicating the mk VII 303 round

[ssj]

Hi, Im looking to replicate the above round as closely as I can for 300, 500 and 600 yrd matches out of a no4. Digging around Im not finding a hell of a lot of good info, especially around the resonance aspect. Does anyone have some good sites or pointers? I tend to use 1943 (if I can get it) or Privy Brass as a basis. I have Barnual 175gr flat base FMJs.

One thing Im not clear on yet is, was cordite still used in the mk VII bullet for all its service life? ie even into the 1950s and 60s (or did they just use up war stock?), or was a newer propellant used?

Any free ballistic charts on the net for 300, 500 and 600yds? (especially fps at500yds as I'll be shooting this weekend) I suspect Im going to be around 40gr of ADI 2208...

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[Bruce_in_Oz]

The "Vll" is primarily the bullet type.

There is such a thing as "Mk Vll Z" which is a Mk7 bullet propelled by a granular Nitrocellulose brew as opposed to "good old" Cordite.

The trick with Cordite is how to get the "bundles" of the stuff into the tapered, necked case. Short answer: you don't!

Ever tried to get them out???

How about: Drop the bundle of sticks into a straight case, (looks like a .444 Marlin) and then form the brass to final shape?

This, as opposed to fully formed, annealed and primed cases getting a shot of granular propellant as they travel around the big rotary machines.

In terms of the end result: Same meat; different gravy, or something.

The introduction of Cordite happened at the same time that the rest of the world's ordnance systems were coming to grips with "smokeless" propellants in general.

The retention of the "big", chlorate-rich primer in cordite STICK loads MAY also be related to the fact that the bundle of Cordite was not "disturbed" by the initial flash and thus, required a bit more "encouragement" to fully ignite. Thus a sort-of "progressive" burn that suited the big, heavy round-nosed bullets and carried on nicely to the Mk7.

Note that the "big" Chlorate / Mercuric Fulminate primers also had the advantage of being stable and reliable at pretty much any temperature likely to be encountered on this planet. (That of course, is if manufactured and stored correctly, which also applies to ANY priming compound).

[ssj]

VII Z, yes I can see that and it has the same muzzle FPS by the look of it. So when did the VII Z become the "norm"? Pre WW2?

Ive spent the last few hours looking for info and not coming up with much except maybe rather hot looking ADI 2209 loads, like 46grains.

[Bruce_in_Oz]

Not sure if Vll Z ever became a universal norm.

As near as I can establish, Australia, for one, only ever made the “traditional” Mk Vll ammo (plus the usual tracer, etc.)

The “Z” indicates the use of a granular, nitro-cellulose propellant. OZ MF head-stamped 9mm ammo carried the headstamp “2Z” for decades after WW2.

All US contract Mk7 ammo was filled with granular, nitrocellulose propellants and thus should carry a “Z”.

Quite a lot of the WW2 Canadian .303 ammo also carries a “Z”, but they also made prodigious quantities of “regular” Mk Vll with the Chlorate / Mercuric primers and proper Cordite.

No idea about the minutiae of South African production.

[Bruce_in_Oz]

For the truly keen, there's this site:

Headstamps of the .303 British Calibre Service Ammunition Round

[Bindi2]

Unless you have the Mk7 projectile duplicating the ballistics is a non event. Using a chronny for reloads and Milsurp, then shooting 3,5 & 6 will show different elevations. 2208 gives the best load up to 180gn then it is a toss up between 08 & 09 for the heavies. Just build a load that suits your rifle and write down the elevation numbers for each range. The military rifle sights were zeroed to centre POA, target shooting is to 6 oclock hold centre POI unless you have a ring fore sight.
I also know some reloader shooters use 2206h.

[ActionYobbo]

as far as powder goes 3031 is the closest to cordite and bench mark 2 is close to 3031 so is the old 2206. as for the projectile the Mk7 had 2/3 of its weight in the rear 1/2 so as far as I know the only commercially available projectile that comes close is the matchking but its a BT

[WarPig1976]

POF .303 surplus ammo.. shoot or save?

FWIW, If you can get your hands on some old surplus .303 that hang fires or is other wise junk you can reclaim the cordite and the bullet. It's a very simple process to remove the cordite, all you need is a paperclip and twizzers. Replacing it into a new case with a good primer is simple and pain free also.

[Bindi2]

as far as powder goes 3031 is the closest to cordite and bench mark 2 is close to 3031 so is the old 2206. as for the projectile the Mk7 had 2/3 of its weight in the rear 1/2 so as far as I know the only commercially available projectile that comes close is the matchking but its a BT

Know about 3031 it produces to high a pressure curve for too low a speed. It was the powder used when the shoulder was the closet we could judge power till a chronny appeared in the 70s proving the shoulder was not even close. I have very early manuals which suggested 3031 was the way to go and ignorance was bliss.

[Bruce_in_Oz]

And, having salvaged the propellant and bullet, you can salvage the unfired brass if you use hydraulic decapping. This method ensures that the case is not contaminated by the metallic mercury released upon ignition of the original primer. However, "ancient" brass may also be subject to age-cracking in the neck because of unrelieved stresses that have been there since the bullet was seated; NECK only annealing may or may not help. Some ammo will crack down past the shoulder if it has been really poorly treated at manufacture. Much of this stuff may well crack severely on firing.

HOWEVER, the more enthusiastic, (hard-core reloaders), would strip the ammo right down, including removal of the live primer by hydraulic pressure, and then refill the "new" brass with commercial components; not an economical proposition these days, unless you are getting the Ball ammo for nothing.

And, if you do salvage the cordite sticks (and don't contaminate them with your sweaty paws), good luck shoving the proper amount back into the necked cartridge.