.303 Corrosive/Non-Corrosive Database?

[tj214]

Either I'm not using the correct search terms or no master database of which .303 ammo is corrosive and which non-corrosive seems to exist. I can find bits and pieces all over the net, but does such a master database exist anywhere?

With the massive accumulated knowledge here and a couple other places I'd think all the data is available to show which manufacturers/years of manufacture are corrosive.

Can you point me to it (if it exists)?

TIA

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Daan Kemp]

Much easier just to pour boiling water through the barrel after shooting.

[Alan de Enfield]

Either I'm not using the correct search terms or no master database of which .303 ammo is corrosive and which non-corrosive seems to exist. I can find bits and pieces all over the net, but does such a master database exist anywhere?

With the massive accumulated knowledge here and a couple other places I'd think all the data is available to show which manufacturers/years of manufacture are corrosive.

Can you point me to it (if it exists)?

TIA

All ammunition is both corrosive and errosive, just the 'amount' varies.

Cordite loaded rounds affect the leade and first couple of inches of the barrel whilst NitroCellulose rounds affects the whole of the barrel to the muzzle (which is why the 'bullet in the muzzle' test tells you nothing about a rifle that has spent it life shooting cordite rounds.)

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

APPENDIX 15

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 stenciling 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.



If you are worried about chemical corrosion (such as from merciurail primers) just do what the military did :

[Daan Kemp]

The accuracy deterioration using cordite and then NC does seem extreme. It indicates that 'all' LE rifles having fired cordite are now inaccurate, as cordite rounds aren't around any more?

[Alan de Enfield]

The accuracy deterioration using cordite and then NC does seem extreme. It indicates that 'all' LE rifles having fired cordite are now inaccurate, as cordite rounds aren't around any more?

I think that is probably true for the well-used barrels with 'cordite erosion' half way up the barrel, but there are still a good number of 'lightly used' LE's about

By the late 40s I think that Cordite was well on its 'way-out' and MKVIIZ had been introduced. Cordite rounds finally ceased production in the UK in the early 60s.

[CINDERS]

Most of the early 303 ammo & WWII vintage is collectible now besides given the age of them results can vary, I had a fair few click bangs and hang fires using 1967 POF ammo early on when I started milsurps shooting, but what do you expect (Possibility Of Firing).

[Alan de Enfield]

Most of the early 303 ammo & WWII vintage is collectible now besides given the age of them results can vary, I had a fair few click bangs and hang fires using 1967 POF ammo early on when I started milsurps shooting, but what do you expect (Possibility Of Firing).

Percentage of Failures

Probability of Failure

Pauses on Firing

[CINDERS]

[Mk VII]

No authoritative information has been published.

The latest British stuff I've seen with cordite is 1960. I recall being told that they switched to Eleyprime the following year. The 1970's British 7z I've seen has noticeably less corrosion in the cap chamber after firing and that suggests non-corrosive.

[browningautorifle]

I doubt you'll actually be able to get any corrosive ammo in any bulk today, or actually be able to shoot it reliably. I'd think most of what you'll find now is FNM or HXP and Prvi Partizan. I made a habit of stripping other headstamps for the components and re-priming for reliability.