.303" tolerances

[Simon R]

What were the manufacturing tolerances for the production of .303" cartridge cases and bullets 14-18?

At what rate were cases/bullets inspected? Does an inspected round have an inspection mark?

[Heatseeker]

What were the manufacturing tolerances for the production of .303" cartridge cases and bullets 14-18?

At what rate were cases/bullets inspected? Does an inspected round have an inspection mark?

Can't comment on the ammunition, but from 1916 Australian SMLEs manufactured at Lithgow were "opened up" to the widest tolerances due to vagaries in ammuntion and the dust and grit encountered in the desert campaigns.

For this reason, pre-1916 SMLEs were sought out in World War II for conversion to HT sniper configuration.

[Justin Moretti]

I've got the Textbook of Small Arms 1929 at home, which although post WW1 should have much of the information you seek. When I'm near it next I'll dig it up for you.

Of note is that after WW2, .303 British was banned to civilians without good reason (Farmers, members of rifle clubs) and a 'shortened' version was invented which could legally be chambered in altered .303 rifles. The loose chambers Heatseeker speaks of caused a bit of legal trouble, because the largest of these still had (just) enough clearance to take the unaltered, original military round even after the gunsmithing work had been done!

The rimmed tapering .303 case is godawful for the exacting shot-to-shot consistency that target shooters demand, and for those reloading their own ammunition. It is, however, perfect for loading into a deliberately oversized and possibly grotty chamber while giving safe and reasonably accurate killing performance, which is exactly what it was designed to do.

[Ozzie]

If you contact this site they may have original documents that may help.

http://www.lisp.com.au/~samuseum/

Cheers

Kim

[Simon R]

E-mail enquiry form, now there's at thing, thanks for that.

[4thGordons]

Steve Redgwell's site www.303British.com has a list of stamps and marks and lots and lots of information on the round (historic and current) A while ago there was a publication available from this site entitled (I believe) "The Accurate Enfield" which contains a chapter on "military specifications" of the cartridge. Mr Redgwell's information seems very complete and reliable so it may be worth contacting him if no one on the forum can answer this.

Hope this helps.

Chris

[2ndCMR]

The Textbook of Small Arms 1929 devotes an exhaustive 9 pages to the subject with full page illustrations of the dimensional tolerances.

Suffice to say that - in theory - every aspect of manufacture was tightly controlled and rigidly inspected.

In reality, it is stated in a number of soldier's memoirs that certain ammuntion factories in the US and UK produced ammo that was clearly oversized and made of inferior brass etc. etc.

Machine gunners and snipers were careful to select their ammunition if possible, from factories known to be reliable.

[Justin Moretti]

Machine gunners and snipers were careful to select their ammunition if possible, from factories known to be reliable.

Most fanatical among the machine gun users were the fighter pilots, the more skilled and professional (and fanatical) of whom loaded and (manually) cycled (by pulling on the gun's cocking handle) EVERY round of ammunition they would carry the next day, thus ensuring that there was at least one 'stoppage' they wouldn't be getting (the mis-shaped misfeed). It also ensured that any faulty rounds that were going to have their extractor rims fall off (leaving a broken case inside the gun) would more likely fail on the ground where an armourer must pull clever tricks to remove them, not in flight.

Tolerances in terms of the gap between the cartridge and the chamber wall were, without being exhaustive, in the realm of 0.001 to 0.003 inch in the diameter (closest at the neck of the cartridge from which the bullet protrudes) and 0.005 inch between the length of the cartridge body and the corresponding-shaped portion of the chamber.

0.001 inch = .0254mm. It's easy to understand how inaccuracies in manufacture can combine with shortcuts in quality control (for the sake of rapid delivery) and a thin film of Flanders mud (or Palestine sand) to make life horrible for the people who needed this stuff. That's why the gaps of fractions of an inch, above, were relaxed, so the difference in length and diameter between cartridge and chamber might have a couple more 'thou' (0.001 inch multiples) to play with, and what jammed in your neighbour's Sparkbrook-made SMLE MkIII would feed (however grudgingly) in your Lithgow III*, yet not burst the cartridge asunder when an undersized but still within-limits round went into a loose-cut chamber.

[gew98]

It also ensured that any faulty rounds that were going to have their extractor rims fall off (leaving a broken case inside the gun) would more likely fail on the ground where an armourer must pull clever tricks to remove them, not in flight.

Justin ; The shearing off of rims of rimmed or rimless ammunition cannot happen with simply cycling the cartridges manually. They sheared off ( when it happened ) due to a hard extraction while firing. There would be a number of causes to rim failure while live firing - but never while manually cycling unless O.A.L. of case was way long and or bullet was oversized to cause a tight enough jam where trying to force it would shear a rim from the case. I would as well think manually cycling cartridges in such guns as the Lewis and Vickers would be more likely to cause a failure as cases can get scratched , dented or bent causing a second go around the better chance of a malfunction.

[TonyE]

I fully concur with Gw98's comments about separated cases, as this only happens under conditions of pressure and/or hard extraction. I also doubt if the rounds were manually cycled through the guns before flight. Even under wartime conditions in the field this would have to have been done on the range. What some pilots certainly did do was run the rounds individually through a spare barrel to check fro correct chambering.

To return to the original question re: inspection etc, this was laid out very clearly in the manufacturing specifications. All rounds were subject to various "go/no go" checks during manufacture and all rounds were visually inspected as they came from the line. This normally consisted of a large shuffle tray containing the rounds which were rolled around by the munition girls to check for imperfections, neck cracks etc.

A daily proof was also taken of a sample of the day's production, usually once each shift and fired against "standard" ammunition for velocity, pressure and accuracy.

Having said all that, there were without doubt severe quality control problems with certain civilian manufacturers (Birmingham Metals and Munitions was one) and the American made conract ammo was particularly poor.

Pilots were also trained to clear stoppages in the air and as part of their training would fire belts with either a round missing or a drill round inserted among the live rounds. Also there were special .303 rounds made to cause misfeeds for training. These were known as "Purple Label" ammo and had the bullet seated about 0.1 " lower in the case with the neck indents omitted. They were identified by the packet label being printed in purple and the primer blackened. I have an example in my collection.

There was also a .303" Mark VIIz RC round which was a reduced charge round designed to produce a No.1 stoppage in Vickers guns. It was loaded with 31 grs of cordite. According to LoC it was identified with a 1" blue band around the case and "RC" included in the headsatmp, but no surviving examples are known.

Regards

TonyE

[Justin Moretti]

I fully concur with Gw98's comments about separated cases, as this only happens under conditions of pressure and/or hard extraction. I also doubt if the rounds were manually cycled through the guns before flight. Even under wartime conditions in the field this would have to have been done on the range. What some pilots certainly did do was run the rounds individually through a spare barrel to check fro correct chambering.

So that's how it was done.

My apologies; 'run the rounds through' certainly sounded like the full bottle to me!

I'd imagined that a case separation might happen, again, when the fit was tight but also when the metallurgy had gone awry and induced extreme brittleness (Though misfeeds would then be the least of their problems).

Many thanks for correcting my misconceptions. It must have been the late hour and the fatigue; I had a lot on this last weekend.

[Simon R]

I'd imagined that a case separation might happen, again, when the fit was tight but also when the metallurgy had gone awry and induced extreme brittleness (Though misfeeds would then be the least of their problems).

I had it in mind that it wasn't simply the metallurgy but the manufacturing process too - not being drawn properly, especially as far as the US ammo. was concerned.

Anyway, it's a subject I know little about so all your replies have been highly informative.

[lassuy]

The US ammo depended much on the manufacturer, H. W. McBride in his book "A Rifleman Went to War", says that Winchester was absolute top quality ammunition, but there was "a factory up the Hudson" that produced horrible stuff. As a machinegunner and sniper, he really paid attention to his ammo.

[TonyE]

Are you talking about .303 inch or 30-06 ammo? The .303" produced by the US Cartridge Company of Lowell, Mass. was particularly poor, but I don't think that is "up the Hudson". It would be interesting to know which manufacturer he was talking about.

Regards

TonyE

[MikB]

The rimmed tapering .303 case is godawful for the exacting shot-to-shot consistency that target shooters demand, and for those reloading their own ammunition.

Problems with reloading 303 have little to do with the case design. Two design charactristics of the SMLE rifle contribute to it:-

i) As well as being oversize on the tapered case diameters, chambers are very often shouldered .050" or so deeper than the shoulder on a new case. Headspacing on the rim, this theoretically doesn't matter - except that, when the shoulder's blown forward on gunfire, the work-hardened shoulder is not simply displaced with consequent shortening of the neck, but the case wall is stretched just forward of the web. This leads to a high risk of case head separation at this point with reloads, which I've experienced many times. When it happens, there's no difference in the 'feel' of the shot, and no apparent gas leakage - sometimes I've not realised it's happened until I fail to chamber the next round.

ii) This is all exacerbated by the springiness of the action, due to the bolt locking lugs being behind the magazine well. This same feature is also responsible for the speed and slickness of operation.

Make no mistake, I love the 303, but it'd be silly to be blind to its drawbacks.

Regards,

MikB

[Justin Moretti]

Problems with reloading 303 have little to do with the case design. Two design charactristics of the SMLE rifle contribute to it:-

i) As well as being oversize on the tapered case diameters, chambers are very often shouldered .050" or so deeper than the shoulder on a new case. Headspacing on the rim,

... is in fact the only circumstance in which this shouldering slackness is permissible in the first place. Agree. Steve Redgwell (website quoted above) is very big on neck sizing only for this very reason, minimizing working of the brass (I imagine military surplus with corrosive primers would be even worse than modern stuff.)

ii) This is all exacerbated by the springiness of the action, due to the bolt locking lugs being behind the magazine well.

I wonder whether this changes at all for P14 owners (those who haven't taken advantage of the stronger action to rebarrel to something else!).

We're probably at cross purposes - I might have been clearer, but my point was to do with the combination of the tapered cartridge and loose cut chamber being best for their specific purpose, a military rifle and ammo designed to function under the filthiest imaginable circumstances, with no concessions to case life or the fanatical concentricity and chamber-bullet-barrel fit demanded by the benchrest target fraternity. i.e. The fact that it is godawful for reloaders is an inevitable consequence of the rifles it was designed to be fired in, on which we agree. There is of course the argument over whether powder burns more consistently or efficiently in a 'short fat' rather than a 'thin tapered' case. But this is almost irrelevant for cordite, which exists as thin strips that extend the whole length of the case anyway, rather than powder granules which can be 'blown down the barrel' by the initial explosion of the charge next to the primer.

I don't think anyone's really interested in doing the experiments, even if you could form a Winchester Short Magnum-type case around the cordite threads (if there's still new cordite to be had!). That was the other thing about the .303, wasn't it? That the charge was inserted and the final case forming done around it? (Certainly the case for the MkI BP round, and I seem to recall for cordite too.) About the only advantage for cordite is that it DID extend the full length of the case (yes, I know, there was often a wad on top), and so reduced loads wouldn't "settle away" from the primer...

[MikB]

I've often thought that a pussycat first load in new 303 cases might blow the shoulder forward without the caseweb stretch. Then you'd use the shoulder to headspace on and necksize only. But it's a lot of hassle and I haven't got round to trying it.

P14s have been capable of competitive accuracy in 303, but I don't really know how recently.

It is true for cordite, as well as the original BP pellet, that the charge was added before final necking - there's an exhibit in Birmingham Museum of Science and Industry illustrating this, or there was.

Cordite's very energy-dense, but the flame temperature even of the modified variant is still higher than normal modern nitros, with quite serious barrel-life implications, so I very much doubt anyone's still making it. The later MkVIIz 303 used a granular propellant sometimes known as 'Neonite' and much like medium-rate nitro powders, so it's reasonable to think cordite was already dropping out of use before 303 was superseded.

Regards,

MikB

[TonyE]

There is no longer any cordite production anywhere.

With regard to the last comment re: Mark VIIz, the original nitro powder used in WWI was DuPont 16, and this was subsequently manufactured in the UK. Following WWI, production of ball ammo reverted to cordite and this remained the case until WWII. Then again some use was made of NC for Mark VII ball rounds, but most NC was used in incendiary and Ball Mark VIIIz.

After the war we again went back to cordite right through to the end of .303 production in the early sixties. There was one final production run of .303 7z by Radway Green in 1973 for the cadet forces that used NC as there was no rifle cordite available.

Regards

TonyE

[MikB]

After the war we again went back to cordite right through to the end of .303 production in the early sixties. There was one final production run of .303 7z by Radway Green in 1973 for the cadet forces that used NC as there was no rifle cordite available.

Regards

TonyE

Was there no 7z in the mid-60s? I have memories, maybe spurious, of being able to hear powder in shaken 303 rounds and a change of smell from the burnt-orange-peel of Cordite to the salt-and-pepper of nitro in about 1967...

Regards,

MikB

[Pete1052]

When the head of a shell casing separates from the rest of the casing after a cartridge has been fired it is almost always due to excessive headspace--that is, excessive space between the face (front) of the bolt and the head (or rear end) of the cartridge. Weapons that do that need to be checked by a competent gunsmith or armorer before they cause serious injury or death.

[Justin Moretti]

There is no longer any cordite production anywhere.

With regard to the last comment re: Mark VIIz, the original nitro powder used in WWI was DuPont 16, and this was subsequently manufactured in the UK.

I am given to understand that Dupont 16 has since become what is now called IMR3031, and that it was introduced originally to fill US-produced ammo as they didn't use cordite, and understandably didn't want to start learning to make it if something just as good was available already.

Interestingly, the internal ballistic program "Quickload" (available through www.neconos.com FYI) essentially duplicates original .303 MkVI and VII ballistics (within reasonable margins of variation) when a bullet of the appropriate length and weight is specified together with a charge of 3031 the same weight as the original cordite charge. The weight of Dupont 16 was not quite the same as that of the cordite charge, but there have probably been changes in performance over the years to account for the difference, and the program I mention makes certain assumptions that may or may not be valid for mercuric primers and older manufacturing processes/chemical compositions. Nevertheless, it's surprising how the values average out!

[TonyE]

Yes, DuPont 16 became IMR3031 and it is quite possible to replicate the military load. There was no change in specification of the performance of the Ball Mark VII, any variation in propellant weight being due to the differences in the performance of different propellant batches. The same applies to cordite.

Each batch of propellant was fired against standard rounds and the charge weight of the production ammo adjusted to give the correct ballistics. The charge is approximately 37 grains but can go either side of that.

With regard to NC loadings for Ball Mark VII, in WWII I only know of Royal Laboratory in 1942 and 1943. Post war I only know of the 1973 RG, but Kynoch made one batch of Ballistic Standard 7z in 1948. They also loaded some commercial target ammo headstamped KYNOCH 7z. In addition the Canadians loaded some 7z in the fifties. I have DAC for 51,56 and 58.

RTegards

TonyE

[gew98]

P14s have been capable of competitive accuracy in 303, but I don't really know how recently.

Regards,

MikB

Mik ; I have found the unboogered with original ( matching not FTR'd ) Patt 14 rifles absolutely above SMLE accuracy. My example is a five digit serial ERA made rifle - matching and it's only non original issue marking is the EY marking added to butt and receiver when it was reissued to the home guard during WW2. Anyhow it has a perfect bore and shoots absolutely fantastic groups , above and beyond my best smelly's and they do damn good too.. IMHO there is no "have been" , but are capable in competitive accuracy right off the rack.

[MikB]

...above and beyond my best smelly's and they do damn good too.. IMHO there is no "have been" , but are capable in competitive accuracy right off the rack.

I don't doubt it.

But, whilst there are plenty of P14s still shooting the Target Rifle circuit in the UK, most of them are refurbs, at 'club gun' level rather than in the hands of the top shooters, and I've not heard of any in 303 recently. So I couldn't say whether they could compete against modern target rifles, for which a benchmark accuracy standard would be MOA out to 600 yards or so, prone with sling but no other support. If you can do that, then yes, thay are still competitive.

Regards,

MikB

[cahoehler]

Guys

This has probably been done in another thread AND also I should be able to find out for myself

BUT

why would most of the ammunition in 1914 fit the new short rifle BUT not the old long rifle?

When Allenby gave the cavalry the "long rifle" was that good or bad ? or just better than a lance / sword ?

Thanks

Carl Hoehler