Anyone know how they came up with the standard .470 case head diameter?

[AbitNutz]

It looks like the almost universal .470 case head/rim diameter (11.94mm) started with Mauser in or about 1888, originally called the 7.92x57. Does anyone have a notion on how they settled on .470? I mean it's such a weird size. Why didn't they go to .500 or even to 12mm? Is there some efficiency between the stock steel diameters they used for rifle bolts and .470? Or perhaps the raw brass came in a size that when you ran it through comes out to .470?

No other ideas here...stuff like this just bugs me.

[Ballistics in Scotland]

The dimension listed in references varies from .469 to .472. .470 is only about .0024 under 12mm. That is about as accurate as cases get. The

[OS OK]

I would imagine that a group of German engineers came up with that dimension only after considering what they reasoned was an appropriate size case that would allow ignition of the volume of powder and efficiently expel it into the barrel without excessive shoulder restriction. Straight wall cases don't have a shoulder restriction but to load higher volumes of powder would necessitate some pretty long cases, it could be that the bottleneck is a compromise of sorts and 12mm was a good place to start with the existing dimensions of available tooling in the day.

Other than this, "no idea!"…OS OK…I imagine it had a lot of math and physics thrown into it too.

[AbitNutz]

That's true but it started with with Mauser and everyone else just based their cartridge on that one. What's up with such an odd dimension? Why not start with 12mm or .500?

[OS OK]

There are standards, but they are called out by 1 size only in specifics , they established a maximum and minimum size for each chamber and each specific caliber falls within a min/max range as made by various manufacturers. Actual dimensions then can vary on each case even though it is specified as a certain caliber.

[Jeffrey]

I am not an engineer or machinist, but I am a fan of trivia. Could it be that the 12mm tool was used to ream out the chamber, and the .0024 quoted by Ballistics in Scotland is awfully close to 1/100 of a millimeter. That clearance sounds to me like a good starting place to shoot for when designing a brass shell inserting into a steel hole given things like manufacturing tolerances. Also consider the different coefficients of thermal expansion for steel and brass / bronze. The brass cartridge must be easily inserted into a steel chamber. After that cartridge goes off, the case must be easily extracted.
That's true but it started with with Mauser and everyone else just based their cartridge on that one. What's up with such an odd dimension? Why not start with 12mm or .500?

[Ballistics in Scotland]

I don't know if multi-bladed reamer blanks were available then, or even if they are now. It is possible that the original 8x57 round was developed with reamers ground from standard 12mm. ones. It would be easier to grind them just a fraction under the original figure.

[OS OK]

SAAMI | Sporting Arms and Ammunition Manufacturers' Institute (http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjego3ir4fNAhUC6GMKHXbKB9QQFggdMAA&url=http%3A%2F%2Fwww.saami.org%2F&usg=AFQjCNG09UdvqB132nogZPVqT-8Si0rdSA&sig2=l-HTnH-0EDg4fl7azVmCGw)

[Outpost75]

Reamers ground from 12mm stock is correct. Mauser also pioneered the tooling convention which started with a 3-flute core drill, 4-flute rougher, 5-flute semi-finish and 6-flute finish reamer to avoid tool chatter and to enable setup men and machine operators to quickly determine that the correct reamer was in use for that operation. Standard IE practice still used today.

[Earlwb]

I think there were more than one standard for the cartridge case size that came out way back then. The French had the short and bulbous 8mm Lebel round. The Austrians/Germans has the 7.92x57mm round. The British had the .303 round for the Enfields at the time. The Americans had the .30-40 Krag which evolved into the .30-03 and then the .30-06 over time. I believe that each cartridge size was governed by the powder charge used. Thus they made the cartridge to hold the powder charge needed for that particular cartridge. Not the other way around. The British at first used cordite which comes in stands. If I remember right the .303 just barely held thirty strands of cordite. it must have been a PITA to get those strands in the cartridge case. Each of the other countries all had their own preferred smokeless powder to use too and they had to make the case to fit that charge.

Now then the 7.92and 8mm German cartridges were of tremendous interest to the US military at the time. No doubt the Spanish American war where the Spanish were using the 7x57mm cartridge in their rifles and it out performed the 45-70's and 30-40 Krags at the time. So the .30-03 and .30-06 were no doubt influenced by it.

I also agree with the others in that 12mm or 1/2 inch just happened to be convenient for a dimension size at the time too.

[Ballistics in Scotland]

Reamers ground from 12mm stock is correct. Mauser also pioneered the tooling convention which started with a 3-flute core drill, 4-flute rougher, 5-flute semi-finish and 6-flute finish reamer to avoid tool chatter and to enable setup men and machine operators to quickly determine that the correct reamer was in use for that operation. Standard IE practice still used today.

I was suggesting (by guesswork) that ordinary engineering 12mm. reamers were used, but I suppose 12mm. steel rod is also possible. The sequence of flute numbers is interesting. When I chambered my .300H&H Magnum I used only a six-flute finishing reamer, and I did notice very fine longitudinal fluting in the chamber, so shallow it was visible with a bright light down the bore, but couldn't be measured and was invisible on a Cerrosafe cast. Much deeper and wider fluting is common in automatic weapons, and I think the most the finer chatter could do, if it is longitudinal, is assist extraction. If anything.

[Ballistics in Scotland]

I think there were more than one standard for the cartridge case size that came out way back then. The French had the short and bulbous 8mm Lebel round. The Austrians/Germans has the 7.92x57mm round. The British had the .303 round for the Enfields at the time. The Americans had the .30-40 Krag which evolved into the .30-03 and then the .30-06 over time. I believe that each cartridge size was governed by the powder charge used. Thus they made the cartridge to hold the powder charge needed for that particular cartridge. Not the other way around. The British at first used cordite which comes in stands. If I remember right the .303 just barely held thirty strands of cordite. it must have been a PITA to get those strands in the cartridge case. Each of the other countries all had their own preferred smokeless powder to use too and they had to make the case to fit that charge.

Now then the 7.92and 8mm German cartridges were of tremendous interest to the US military at the time. No doubt the Spanish American war where the Spanish were using the 7x57mm cartridge in their rifles and it out performed the 45-70's and 30-40 Krags at the time. So the .30-03 and .30-06 were no doubt influenced by it.

I also agree with the others in that 12mm or 1/2 inch just happened to be convenient for a dimension size at the time too.

The .303 cartridge was first issued with a compressed and pierced pellet of solid black powder, which had been used in military rockets since Napoleonic times. But it was designed in the expectation that a "chemical powder", as the French were already known to have, would be used. I doubt if they knew it was going to be stranded. The sights of the Lee-Metford were actually graduated for about 50ft./sec. more than black powder would give, which was a pretty good guess.

In fact they didn't load cordite into the case as presently constituted. They necked down the straight case after insertion of the powder.

[M-Tecs]

Standardization in manufacturing didn't start at the national or global level start until after 1900. Since Mauser's chamber reamers were undoubtedly designed and manufactured in house the reasons as to why could simple be nothing more than "cause that's the way they wanted to do it."

https://en.wikipedia.org/wiki/American_system_of_manufacturing

Interchangeable parts started in use around 1800 but global standardization took another hundred years.

[EDG]

I don't think anything was standardized from the powder charge or cartridge side. Rather manufacturing ease and rifle design had more to do with it.
Many of the rounds had a head around 11.5mm and were both rimmed and rimless. (6.5 Dutch, Italian and Mannlicher-Schoenauers, .303 Brit and .30-40 Krag)
The Mausers and derivatives were 12mm (.472). I think most of the fat cases were just carry over from black powder rounds.



I think there were more than one standard for the cartridge case size that came out way back then. The French had the short and bulbous 8mm Lebel round. The Austrians/Germans has the 7.92x57mm round. The British had the .303 round for the Enfields at the time. The Americans had the .30-40 Krag which evolved into the .30-03 and then the .30-06 over time. I believe that each cartridge size was governed by the powder charge used. Thus they made the cartridge to hold the powder charge needed for that particular cartridge. Not the other way around. The British at first used cordite which comes in stands. If I remember right the .303 just barely held thirty strands of cordite. it must have been a PITA to get those strands in the cartridge case. Each of the other countries all had their own preferred smokeless powder to use too and they had to make the case to fit that charge.

Now then the 7.92and 8mm German cartridges were of tremendous interest to the US military at the time. No doubt the Spanish American war where the Spanish were using the 7x57mm cartridge in their rifles and it out performed the 45-70's and 30-40 Krags at the time. So the .30-03 and .30-06 were no doubt influenced by it.

I also agree with the others in that 12mm or 1/2 inch just happened to be convenient for a dimension size at the time too.

[northmn]

You touched on the fact that conversions from metric to English make for some interesting measurements. Metric measurements sometimes yield an irrational number (one with an infinite number of digits after the decimal) on conversion. Funny thing to me is that the 30-06 must have been based on the military 8mm Mauser as the case head is the same and I have made many cases from 30-06 for the 8mm Mauser. Europe and the rest of the world is standardized on the metric system. I remember one of the first times we vacationed in Canada. I had to multiply the Canadian speed limits by .6 to get the MPH from KPH. Now cars have them on the speedometer. Its the conversion that is a problem not the use. Actually the Europeans have the same problem converting our strange measurements to metric. Our 358 is their 9mm at 355.
Some case dimensions were also a carry over from the BP days. The 38 special is based on the conversion of the 36 Cap and ball revolver to cartridge. The cylinders were 380 and 38 special cases measure 380. 454 diameter for the 45 was based on the Colt chamber and bore of 454 for the 44 Cap and Ball.

DP

[shredder]

Mauser in fact had nothing to do with the development of the 7.92x57. That cartridge was developed with the 1888 Commission rifle. After the fact, the Mauser brothers used the basic case and necked it up and down for the various incarnations.

[Ballistics in Scotland]

Mauser in fact had nothing to do with the development of the 7.92x57. That cartridge was developed with the 1888 Commission rifle. After the fact, the Mauser brothers used the basic case and necked it up and down for the various incarnations.

That is certainly true of the J-bore version, as designed under the auspices of the German Commission for their rifle of 1888. But I think Mauser would have had considerable input into the redesign of the cartridge into the S-bore version, with a .323in. bullet instead of .318, after the latter had been used for seven years in the Mauser 98 rifle. I believe though I'm not sure, that it was with this redesign that the 7.92mm. designation was first used.

[runfiverun]

except they based them both off the 7x57 case.

[leadman]

The 7.65X53 Belgium Mauser case was first chambered in the 1888 Belgium Mauser. The 8X57 was a product of the German Commission that put together the 88 Commission rifle that Paul Mauser had nothing to do with. The was an earlier version of the 7.65 X53 that was basically the same except it had a rim in an earlier version of the 1888 Bel.Mauser.
I can't say for certain if the 7.65 X 53 or the 8 X 57 was first, but I lean towards the 7.65 X 53 as first.
The USA copied the case for the Spanish Mauser, which was the 7 X 57, after the Spanish American war and developed it into the 30-03, then the 30-06. We even paid Mauser royalties until WWI started for copying his designs for the 1903 Springfield rifle.

[Ballistics in Scotland]

Certainly the 7x57 came after the 7.65x53 and 8x57. It first appeared in the Spanish M93 Mauser.

It is true about the US paying royalties for the Mauser design, but not, as people often say, that the Springfield was based on the Mauser 98. Nothing Mauser in the design couldn't be derived from the earlier models.Vickers, Sons and Maxim in the UK were surprised, after the war, to receive a large cheque from Loeuwe as royalties on the Maxim gun, but I think everything patentable by Mauser that Springfield used would have expired by that time.

First World War American media made much of a supposed Herr Mauser who worked for Remington, observed the Lee action and decamped for Germany with his pirated design. This is not entirely baseless, for a Franz Mauser, elder brother of Paul and Wilhelm, did work there, and may even have facilitated the interchange of ideas which characterizes this industry. But Franz's identity was well known, and he remained in America until he decamped for an allegedly better world instead of Germany, by dying in 1893. That was before Lee build a front-locking rifle, but around the same time as Mauser did so. Besides, it would have been easier and cheaper to buy copies of the US patents, as no doubt they did.

[leadman]

Yes, the design for the 7X57 was not done until the 1892 Experimental model was done for what became the 1893 Spanish Mauser. The 1893 Spanish Mauser was the initial inspiration for the 1903 Springfield as many were shipped to the USA after the Spanish American war. Before the 1903 our troops were using the Krag with a single locking lug and old Trapdoor rifles. There were some Navy straight pull Lee rifles in the late 1890s also.
It is difficult to pin down actual dates when most of the development in that era occured as different sources give different dates. I do have a book on the Argentine Mausers Colin Webster in which there are copies of the original contracts and correspondence from Argentina and the Mauser plant. Argentine had exclusive right to determine which South American countries were able to obtain Mauser rifles for a 5 year period due to a clause in their contract with Mauser. Argentina did much development work with Mauser, especially with the 1891 Mauser which was their main battle rifle until the 1909 Mauser was put in service.

[Ballistics in Scotland]

Yes, it is a sobering thought that Argentina was at the time a prosperous and civilized country, even by First World standards. But some time later Bolivia was the country that received German military training. Thurlow Craig, my favourite author on shooting, fishing, cowboying and South American revolutions, had an inbuilt prejudice in favour of the gauchos of western South America. He thought they had better material in the ranks, and the Paraguayan officer class were a sorry bunch, but the Bolivians were far superior in the officer corps.

[mac60]

I would imagine that a group of German engineers came up with that dimension only after considering what they reasoned was an appropriate size case that would allow ignition of the volume of powder and efficiently expel it into the barrel without excessive shoulder restriction. Straight wall cases don't have a shoulder restriction but to load higher volumes of powder would necessitate some pretty long cases, it could be that the bottleneck is a compromise of sorts and 12mm was a good place to start with the existing dimensions of available tooling in the day.

Other than this, "no idea!"…OS OK…I imagine it had a lot of math and physics thrown into it too.

In the Handloader's digest 11th edition on page 59 there's an article entitled "8mm Mauser: Daddy of them all" by Konrad F. Schreier, Jr. It's an interesting piece and a good read. On page 61 he states "...As for the new case, it's very useful diameter was chosen to accommodate the desired charge of smokeless powder; by chance as much as anything else, the 8mm case has proven ideal ever since"... In my eyes that comes as close as possible to answering the OP's original question.

[JHeath]

Are we certain the rifle was designed around that cartridge, not the other way round? If the receiver ring were designed first, the designers would want to leave a certain chamber wall thickness. Maybe the metric equivalent of 0.470" was as big as they could go with an existing ring design.

Or if the bolt face had been intended for some bygone rimmed cartridge, the new cartridge might have been made to match.

[Bigslug]

I don't know the answer, but I would guess that you're looking at it the wrong way. Instead of starting cartridge design with a blank sheet of paper and saying "let's make this cartridge an even number fractions of a cubit long, this many even fractions of a furlong wide, and have it weigh this many stone", the engineers were probably looking more at what the rifle needed to do - what it needed to weigh, what space it needed to fit in, how far it needed to reach, how big a slug it needed to throw and how far, how strong the metal alloys used were, how much mud the gun had to work with in the innards, etc. . .and designed the round to fit inside that box.

If the rifle works better with a dimension that is 0.48732568 of a unit instead of a "sensible" 0.50, an engineer will only care if there is a damn good reason to.

[AbitNutz]

In the Handloader's digest 11th edition on page 59 there's an article entitled "8mm Mauser: Daddy of them all" by Konrad F. Schreier, Jr. It's an interesting piece and a good read. On page 61 he states "...As for the new case, it's very useful diameter was chosen to accommodate the desired charge of smokeless powder; by chance as much as anything else, the 8mm case has proven ideal ever since"... In my eyes that comes as close as possible to answering the OP's original question.

I believe that answers the question as best it can be answered....

[AbitNutz]

I don't know the answer, but I would guess that you're looking at it the wrong way. Instead of starting cartridge design with a blank sheet of paper and saying "let's make this cartridge an even number fractions of a cubit long, this many even fractions of a furlong wide, and have it weigh this many stone", the engineers were probably looking more at what the rifle needed to do - what it needed to weigh, what space it needed to fit in, how far it needed to reach, how big a slug it needed to throw and how far, how strong the metal alloys used were, how much mud the gun had to work with in the innards, etc. . .and designed the round to fit inside that box.

If the rifle works better with a dimension that is 0.48732568 of a unit instead of a "sensible" 0.50, an engineer will only care if there is a damn good reason to.

As an engineer, admittedly of the ones and zeros type, one thing you think about is availability of raw stock and how little you need to do it it to make it fit your needs. If, for example, my part is .0031 cubits and raw stock is readily available in .500, I can tell you my widget will likely be .500, all things being equal. The cost factor will dictate this. There's no reason to size something in an off the wall size if raw material is more available and thus cheaper, in a standard size.

[M-Tecs]

In the 1870's and the 1880's the folks doing the development generally didn't have engineering degrees. Both Paul Mauser and John Browning were sons of gunsmiths. They did things basically because the wanted to do it that way for a myriad of reasons. Most of which we are left guessing at today. Some worked some didn't. The ones that worked continued to be improved on. We are left with that legacy today. Mostly the guns were designed around a cartridge.

[Bigslug]

As an engineer, admittedly of the ones and zeros type, one thing you think about is availability of raw stock and how little you need to do it it to make it fit your needs. If, for example, my part is .0031 cubits and raw stock is readily available in .500, I can tell you my widget will likely be .500, all things being equal. The cost factor will dictate this. There's no reason to size something in an off the wall size if raw material is more available and thus cheaper, in a standard size.

True, but my point was more to looking at where in the whole process of building a rifle/ammo system are those standardized sizes most applicable. It could be by the time you look at what your metal and machinery can do, and what your final product needs to do, what forces it will be subjected to, and then start from the outside of a standard size block of steel working your way in with standard tooling, that it ends up being the cartridge that has to be the thing with the odd numbers. Tolerances will stack to a certain set of workable measurement ranges, and they usually don't end up with the micrometer reading --.000".

Might also be that the angle of the body deemed necessary for both feeding and extraction, coupled with the amount of propellant it needed to hold, dictated the size of the case head.

Just sayin' the engineers had more on their plate than having their case head arbitrarily work out to a pre-determined number.

As to why it got standardized later, that's easy - less machining to chamber more rounds of different performance envelopes on the same action.

[MtGun44]

12mm.

Engineers make stuff to handy dimensions. Nothing magical about it.

Bill

[JHeath]

12mm.

Engineers make stuff to handy dimensions. Nothing magical about it.

Bill

????

The .22 Hornet has a base diameter of 0.298"

The .222 Rem has a base diameter of 0.376"

The 6.5x55 has a base diameter of 0.480"

The .284 Win has a base diameter of 0.501" but a rim diameter of 0.473"

How are these handy dimensions?

The rim diameter of the .284 is handy because it is a historical holdover that fits existing bolt faces derived from the 8x57. Maybe the 8x57 was derived from something, I don't know.

The bottleneck 8mm Rem Mag has a belt diameter held over from the headspacing belt of the .400/.375 Belted Nitro Express. It's a handy diameter because it fits a marketing expectation of people who think brass is stronger than 4140.

[M-Tecs]

Unless someone comes up with a diary from the 1870 detailing the why we only can guess. The 12mm size for a reamer blank makes sense by todays standards, however, we need to look at what was available and how things were done in the 1870's & 1880's.

What sizes and types of steel were available at that time? Interchangeable parts had been used for a hundred years and global standards were still thirty years in the future. The limited reading I have done on manufacturing in the 1870's and 1880's suggest very limited use of what we would call standard sizes today. Reamers likely would have been low carbon steel machined to almost 100% complete than case hardened in a cyanide salt bath. They may have been hand stoned to finial size and sharpness. Tool grinding was much different than today. It would have been done in-house at the Mauser plant. Almost every tool used would have been developed and manufactured in-house simply because they were not available anywhere else.

I think most would be surprised to learn how much today is based on something that someone simply thought was a good idea that worked so it was copied and improved on through the years.

[EDG]

I surveyed the process control system of a company named Ceram Tec in Essen, Germany. The guy running the company was a very formidable technical guy and not a business weenie like you find in US companies. He was a Doctor Eng. In the US a similar title is PHD in Engineering. In his case it seemed to be either materials engineering or mechanical engineering. He was extremely well versed in all manufacturing processes and materials.

We went to a very nice lunch and he was a history of manufacturing geek. According to him much of our manufacturing technology originated with the tradesmen of southern Germany and Switzerland and spread into the rest of Germany down the rivers that flow through the country.
My next stop was to fly to Stuttgardt home of Porsche. I got to see the Porsche museum on the Porsche Campus. The most impressive things in the museum were the hogged out titanium crankshafts for the Porsche flat 12 cylinder race car engines.
Then I went to the next company to survey which was in Plochingen to the southeast of Stuttgart. Sure enough it was on the Neckar River about 50 miles down the river from Oberndorf the home of Mauser.
My last stop on that trip was in another manufacturing company in Winterthur, Switzerland about 60 miles down the road from Oberndorf.

It was a real treat for a manufacturing guy to visit the vicinity of so much manufacturing prowess.

[leadman]

Drawn brass cases were in their infancy at this point in history and it could be as simple as the tooling to draw a brass case was only reliable down to these dimensions. This along with reduced space needed in the case to hold the fairly new smokeless powder and keep the pressures in check could also have affected the dimensions.
The 71 Mauser used a large case with a rim that the bottom was reduced in thickness around the outside edge was an early drawn case design. The 71 became the 71/84 when a tubular magazine was added. Next up was the Belgium rifle that first used a rimmed 7.65 X 53, then the next year became the rimless 7.65 X 53 Belgium, which went on to be used by Belgium, Turkey, Argentina, and many countries in South America thru the Argentine government.
When my friend returns my book on the Argentine Mausers I'll reread the section on the ammo and see if it reveals any more info.

[justashooter]

the 45-70 used a rimmed case with base diameter of .470". the contemporary 11mm (43) mauser was about .480" in base diameter. similar cartridges were similarly sized. it was reasonable to start with rimless cartridges in the same base diameter.

[Ballistics in Scotland]

The diameter for the .45-70 US Government and all its friends and relations was about .500 or slightly larger, and the 11.15mm. Mauser, aka .43, was .516in.

[44magLeo]

I think it was a combination of things that determined the case size. They wanted to propel a certain weight bullet to a certain velocity. The charge of powder to achieve this was a certain volume. They wanted a case that could hold this volume. In the rifle they determined a man could operate a bolt action of a certain length with ease. This set the length of the case. To use a case of .470 let them easily put 5 rounds in a magazine. If the case was sized larger it would only hold 4, without the magazine protruding below the stock. 5 rounds in stripper clips fit the hand well, which made rapid reloads easy. They also fit in pouches well. This size cartridge let the soldier carry a fair amount of ammo without excessive weight. A larger diameter case would weigh more.Perhaps a larger case size would require a larger heavier rifle. I assume they understood bolt thrust. The powder charge needed to propel the bullet to the required velocity created a certain amount of bolt thrust. A smaller case that was a bit longer would have more sidewalls to grip the chamber and reduce bolt thrust. A large diameter would use a shorter case. Now I know this is all conjecture but all these things may have played a part in the decisions that where made. Perhaps a lot of the things I mentioned have little effect on design. I'm not an engineer.Just some one who thinks a lot.Leo

[Wayne Smith]

From what I have read it was not a theoretical exercise. They were doing a lot of experiments and had determined that the 9.3 cartridge was the ideal for compressed BP and then white powder came along and they had to start over. In other words, there was a lot of experimenting going on at the factory.

I just read on the NOE site that the German 88 Commission rifle designers (the Commission) adapted a Swiss Rubin rimless cartridge design. Mabe we need to look at what was going on in Switzerland. We and the Germans copied both the spitzer bullet and the case from them??

[GONRA]

GONRA always assumed its the "German 88 Commission rifle designers" who started it all out.
Who Nos? ???