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> .308” vs .311” or .312”, .318”, .323” etc.
.308” vs .311” or .312”, .318”, .323” etc.
@ 05:49 pm (GMT) |
Craig SanfordAcademic question here primarily concerning the history of cartridge design, measurements and nomenclature. I have wondered about this for a while: why did the Americans develop .30 cal rifles cartridges to use a .300 bore plus .004 for rifling groove depth in order to use a .308 bullet, while the British and Russians developed cartridges to use a .303 bore in order to use a .311 bullet? I have never found a really satisfactory explanation to this. The American version makes logical sense to me, as we went from .45/.458 caliber rifles down to .30/.308 (or .33/.338 or .27/.277 or .25/.257 as it were) whereas the others seem somewhat random by comparison. I am guessing it all goes back to the beginning with the original M/88 version of the 8mm Mauser utilizing a .312 bore in order to use a .318 bullet. My thinking is the British and Russians sought to emulate the German design albeit in their own rimmed cartridges and that’s how they got started with the .311 diameter but used it for the grooves ending up with .303 on the lands. Then of course the Germans went up to the .323” groove dia. I worked at a gun shop years ago that specialized in hard to find ammunition. If I recall correctly we had at least 3 different versions of 8mm Mauser ammo for the different variants that came over the years. I remember one older gentleman had a fine German drilling with 16 gauge barrels over a 7.92x57mm rimmed barrel. The funny thing is nothing about any of the 8mm Mauser cartridges and rifles seems to actually measure at 8mm. Most subsequent metric cartridges seem to adher to whole and half millimeter measurements for their land diameters. This leads to another question: why did Mauser settle on the original measurements for 7.92mm? |
Replies
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@ 11:42 pm (GMT) |
Craig SanfordRe: .308” vs .311” or .312”, .318”, .323” etc.I must correct my typographical error in that the Russians used the .311/.312 bullet in a .300 (not .303) bore diameter, but the premise of the question remains unchanged. |
@ 09:00 am (GMT) |
Nathan FosterRe: .308” vs .311” or .312”, .318”, .323” etc.Hi Craig, obviously neither of us were there so we can only speculate.As stated in the knowledge base 'The .303 British cartridge was designed by a Major Eduard Rubin, superintendent of the Swiss government arms laboratory'. Remaining examples of the Rubin 1886 .303 troop trial rounds can be found among collectors but are extremely rare. Looking at historical notes from the British Text book of small arms 1929, there are not many details. The author states that Major Eduard Rubin had the foresight and enterprise to pave the way for modern cartridge design. The author discusses Frances adoption of the 8mm (.315" bore) Lebel in 1886 followed by Germany's adoption of a 7.9mm (.311" bore) rifle in 1888. The .303 is introduced into the discussion thereafter. The author simply states that Britain followed Rubin's example with the adoption of the .303 cartridge in 1887. It seems that he did not want to give the inventor full credit and state outright that Rubin actually designed the cartridge. Regarding why .30 versus 8mm etc. Studying the manual, it appears that researchers believed that following the adoption of black powder, bores of around .30 caliber were optimal taking all factors into consideration (speed, trajectory, downrange energy, recoil). Not mentioned were the were the patents and political agreements involved. Looking at the time line, the Metford was introduced prior to the German 7.9mm rifle. It doesn't really change anything, there were influential people and factors at play as you suggest. But it was also an arms race, so much so that the .303 was adopted before smokeless powder was available for it. Regarding the finer elements of diameters including groove depth, designers had to consider both bullet material (obturation) as well as potential powder and jacket fouling. Hope that helps a bit. All the best. |
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@ 03:58 pm (GMT) |
Craig SanfordRe: .308” vs .311” or .312”, .318”, .323” etc.Thank you, Nathan, for shedding some more light on this topic. I have a great fascination with the history of cartridge development. There’s so much to learn in the realm of rifle cartridges, both new and old, and the more I learn the more questions I have concerning how it all came to be. Same goes for handgun cartridges, though to a somewhat lesser extent. The nomenclature can be quite confusing for a lot of people. I learned a lot when helping folks find the find correct ammunition for their older guns at the shop years ago. Like how .38 S&W can't go in a .38 S&W Special but .38 Long Colt can, or how .38 Automatic and .38 Super Automatic are different things although they may fit in the same chamber resulting in a potentially unsafe situation. It’s almost amusing to me that we don’t have such developments and proliferation in the realm of shotgunning.. the short action ultra precision 14.5 gauge is nowhere to be found! |
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