i have written in these pages before of the sad fate of perhaps the best "intermediate infantry" cartridge ever developed, the .30/280 british. the .30/280 was adopted along with a companion bull pup rifle capable of selective fire for a short while, but american insistence that n.a.t.o. adopt an infantry round of .308 caliber led to the british government dropping both the cartridge and the rifle, and adopting the fn fal in 7.62x51mm instead.
what the british were hoping to accomplish with the .30/280 and the bullpup rifle was to give the infantry a rifle capable of being used both as an infantry rifle, and a squad support type rifle capable of "machine gun" fire all in one weapon, and with one cartridge. the dream vanished with the adoption of the fn fal in 7.62x51, as the round proved simply too powerful to control in full auto fire in the relatively light weight fn fal and the american m-14.
no infantry round since has really approached the virtues possessed by the .30/280 brit, in terms of light weight, manageable recoil, and a wonderful balance that gave it sufficient power and efficient ballistics. update: a very good history of the em-2 & the .30/280 brit, from the redoubtable russian, and links in his post to some history on the fn fal. this guy is a good read. http://world.guns.ru/assault/brit/enfield-em-2-e.html end update.
it is a pity that it was never adopted by an allied power, and it is god's beneficence that it was not adopted by the communist block, because it was a clearly superior round in terms of being friendly to weapons design, ballistics and logistics.
(and, americans turn your heads, it was simply ballistically superior to the 7.62x51mm nato. and, kicked far less.)
well, as it turns out, producing a round that duplicates the .30/280 british, if not replicating it exactly, turns out to be ridiculously simple, or so it appears at this vantage.
please allow me to digress, just a bit.--
i have an ar-15 rifle in 6.8mm remington spc, a .277 caliber weapon as opposed to the .284 caliber of the brit. the 6.8mm is a good round, and along with the very similar 6.5mm grendel, is clearly ballistically superior to both the 7.62x39mm model 43 russian, and the 5.56x45mm nato rounds. and, as it turns out, it has a very similar trajectory to that of the 7.62x51mm nato.
but, i have toyed with the idea of trying to get make a rifle in .30/280 brit, ... , well, just because.
just to see if i might be able to make a round that would fit into an ar-15 magazine/magazine well, and have a little more "oomph," i decided to compare the case capacity of the 6.8mm remington spc with that of the 7.62mm nato round. now, it's clear the .308 winchester/7.62mm nato are bigger cartridges: one need only hold them side by side. i knew that if i simply weighed/measured the water of capacity of each, that the larger cartridge would have more volume.
duh!!
the 6.8mm is already a fair performer, so i wanted to see if any discernible performance increase would justify going to all the trouble to recreate the .30/280 brit. i mean, why bother, if there were to be no return on the, ... , well, bother.
so, what i did was get my little dremel tool out, a remnant of a previous existence, and i cut the should and neck section of the case off, leaving just a bare cylinder at the juncture of the case and shoulder: this left a cylinder about 1.31" long, including the head of the case.
i reasoned (imagine that!!) that if i were to stuff a larger case into the magazine well, it would have to be about the same length as the 6.8 case, and that to conform to the requirement, the shoulder of such a case could not extend much past the shoulder of the 6.8mm. so, i got a .308 case, and i cut it just at 1.31" in front of the face of the case head.
so, i had to truncated/cut cases, both about 1.31" long, the 6.8mm being approximately .373" inside diameter at the shoulder, the 7.62mm case being approximately .418" inside diameter at a point well below the shoulder.
now, i used hodgdon h-322 powder in my 6.8mm. i load about 28.2 grains of the stuff behind a 115 grain bullet. not surprisingly, when i fill the 6.8mm's cylinder to where it was cut off, the powder charge weighed 27.5 grains. likewise, when i filled the truncated/chopped off 7.62mm case with powder to its abbreviated length, the powder charge weighed 35.5 grains.
performing the same exercise with hodgdon's h-335 powder, i got about 30.5 grains of powder in the 6.8mm case, and 38.0 grains in the shortened 7.62mm case.
so, it appears to me, that if we compare the case capacity of a 6.8mm case as is, and anticipate the gains in case capacity of a 7.62mm nato case shortened to the same length as the 6.8mm case, but with the advantage of a considerably larger interior diameter, we might expect to achieve a greater powder capacity in the shortened 7.62mm nato of approximately 20% or so, maybe even along the lines of 25% or so.
as a general rule of thumb, first commented on by julian hatcher nearly 60 years ago in "hatcher's notebook," if you increase powder capacity in a cartridge chamber by a given percentage, you can expect a proportionate velocity increase in the realm of 1/4 of the percentage of powder increase. that's not very elegant, but what it means, is that if you increase the powder by 20%, you can expect a 5 to 6% increase in velocity.
my 6.8mm gets a bit over 2550 fps from the present case. increase the powder and get a 6% increase in velocity, and that translates into an increase of 153 fps, or just a tad over 2700 fps with the same bullet, at least in theory. stuff a little more powder into the newly created case, and maybe you get a little more than that.
now, the 6.8mm is .277 caliber. the .280 brit is .284 caliber. how fast you can make a bullet go can be a little arcane, but, looking at the matter as simple mechanics, the amount of power/energy/velocity that can be imparted to a bullet is a function of the pressure exerted upon the area of its diameter, or the base of the cylinder upon which the pressure operates. the pressure being equal (in this case, around 50,000 lbs. per square inch, the operating pressure of the ar-15 series of rifles), the bullet weight being equal or roughly equivalent, the bullet with the larger base area (a function of diameter & circumference) is going to get squirted out of barrels of equal length, faster.
it is as simple as that.
so, a bullet of .284 diameter is going to go a little faster in the scenario.
so, why haven't i just gone out and bought a rifle in .30/280 british, and some .30/280 british ammunition, and just leave all of this alone? well, it's because they don't make the ammo anymore, and they don't make rifles in that caliber.
and, it is pitifully ridiculous how hard it is to find the equipment from which to fabricate your own. if i could find the loading dies to make the "brit," they would probably cost a couple hundred bucks, and a case forming die another hundred or so, and the reamer to cut a chamber in a barrel would cost the talents of a die cutter, and the talents of such a man would set you back another 2 or 3 hundred dollars, american. put it all together, and in labor and materials you are looking $500 to $1000 right square in the face.
if i could find/obtain the dies. they are no where to be found.
i have looked, and i thought i had found a source for the dies, (but not the chamber reamer), but when i looked again this week the format of the company catalog had changed, and the entry for the .280 had vanished.
but, i have done a bit more reading.
and, it turns out, that the .30/280 british cartridge is going to be relatively easy to duplicate, at least in spirit and in general dimensions.
it turns out that in order to try and placate the americans the english ballisticians and engineers proposed a cartridge called the 7x51mm. the number "51" caught my eye. that is the same length in millimeters as the 7.62x51mm nato cartridge. now the americans and the brits were carrying on cartridge and rifle trials all during this process of choosing a cartridge for nato. (you can view them in old british pathe films, ... , thank you google, thank you youtube.)
so, there had to be plenty of interchange going on.
the brits finally adopted a cartridge with the same case head as the american experimental t-65 cartridge, at .473" nominal diameter. the .30/280 brit has a casehead diameter of .473".
so, i got to looking at cartridge drawings and diagrams, with the singular purpose of comparing the dimensions of the .30/280 brit, and the 7mm-08 remington cartridge, a cartridge itself derived from the 7.62x51mm nato round. what if the 7mm-08 is not so very much different in size from the .30/280 brit, as the existence of a 7x51mm british experimental round suggests?, (it occurred to me).
well, when i compared the case dimensions, several interesting things appeared.--
the distance from the case mouth to the case shoulder on the .30/280 brit, encompassing the case mouth, the neck of the cartridge which actually holds the bullet & and the sloping surface of the shoulder, to that point where the shoulder begins is roughly 13 mm's.
the distance from the case mouth to the case should on the 7mm-08 remington, to the point where the shoulder begins, is roughly 13mm's in length. the slope of the shoulder from the point where the case cylinder narrows to its juncture with the case neck, is roughly the same on both cartridges.
the diameter of the case, at the point of the shoulder is not so different.
as a matter of fact, the .30/280 brit and the 7mm-08 remington commercial cartridge (it has never been adopted as a military round) are not so different, except for the overall length.
remember the 1.31" length of the two cylinders i made to measure case capacity?
well, i got a .308 case out, and i scribed a line on the side of the case, radial to its length, right at 1.31". and then, i scribed a line precisely on the point of the juncture of the case shoulder, and the slope of the case to the neck.
and, i measured the distance between them. that distance is .255", right on the nose.
this is my plan, time and finance permitting, but, in theory it should work. so, financial constraints being what they are, e.g., "reality," my theory is simply this.-- i will obtain a set of reloading dies, in caliber 7mm-08 remington, from rcbs, and they will cost in the neighborhood of $50 or so, ... , i don't know, for sure, i've not bought anything like that since before my second divorce and quadruple bypass. laughing.
that's pretty real, eh?
and, i am going to do something odd. i am going to "destroy" them. (ponder that word, "destroy." by doing as i will do, you will destroy the ability of the die to ever function correctly for working with the 7mm-08 cartridge. you will utterly void any and all warranties, express or implied or inferred by fitness for a purpose associated with the equipment. you will be out the labor for altering them. kapish? a good word, destroy, for you are destroying the utility for which the dies were designed. now, consider this is the theory of someone you never met, and upon whom your reliance may work to your detriment. the same goes for my observations on chamber reaming, found in the following post. you proceed at you own risk. ponder that word, "destroy.")
i am going to have a machinist mill, surface grind, or lathe, whatever, the dimension of .255" right off the bottom opening of the dies.
the consequence of this will be that a 7mm-08 remington cartridge case will be shoved up into the die .255" more than would the norm, and that the neck and shoulder will be displaced downward on the axis of the case, and the shoulder will begin .255" "sooner" or "earlier", or, closer to the case head than would otherwise be the case. now, if nothing more were done, we would have a case looking sort of silly, because the neck of the case would now be slightly more than .255" longer than normal, and the shoulder set way back.
so, a die is going to have to have some dimension cut out, and the depriming stem can be removed, so that that excess material can be forced out the end of the die and trimmed to the appropriate length. then the case will be run through another shortened sizing die, to make the final altered case.
now, those of you who have your pencils out will have noted something. the 7mm-08 remington is basically 51 millimeters in length, while the 6.8mm remington is 43 millimeters in length. this means that the 7mm08 is .335" longer than the 6.8's 43 millimeters, and also .335" longer than the 43 millimeters of the .30/280 brit cartridge.
i am only gonna trim off .255" in the process described above. that means that .080" are "unaccounted" for, ... , or, in other words, that the case i am projecting to create through all of this is .080" longer than 43 millimeters. well, as it turns out, the dimension of .080 is basically about 2 millimeters. if all this works out as i hope, this means that the case that emerges from all this tweeking is going to be 1.760" long, or 45 mm's long.
and, this is just the exact length of the case for the 5.56x45mm nato cartridge. that is a major dimension of the cartridge which defined the dimension of the ar-15 magazine well. and, that is the dimension i must comply with to stuff my "version" of a .30/280 british into an ar-15 rifle.
it just sort of worked out that way. i really didn't plan it that way, it just sort of happened. we'll see.
what do i hope to accomplish?
well, it is reported that after wwii the british commission/committee in charge of the cartridge development culminating in the .30/280 brit had a cartridge capable of shooting a 140 grain bullet something over 2700 feet per second. this is very impressive to me, because the load that i am shooting in my 7mm 08 is a 140 grain nosler, somewhere in the neighborhood of 2800 fps, with a fairly heavy dose of powder.
if i ever develop my little theory, i just don't think that i will be able to get that much velocity out of a case .255" inches shorter, ... , remember, we've removed a section of the case cylinder that is basically .420" of an inch in diameter, and .255" of an inch thick. i suppose i could weigh the contents of a 7mm-08 case all the way to the shoulder junction, and compare it with the powder charge of the 1.31" cylinder, and make the quantification exact, ... , but, for right now, it is sufficient to note that such amount is a bunch, as we say in n.e. oregon.
i just don't think i have to nerve to load my little creation, if it ever come to that, with that much powder.
nope, here is my goal. i want to load a sierra match king bthp bullet of .284" diameter (7mm), stock number 1903, that weighs 130 grains, to perhaps 100 fps or so faster than i am am getting out of my 115 grain bullet in the 6.8mm remington spc. if i could get that, and maybe just a sconcy more, i would be just absolutely ecstatic.
i should live so long.
well, it took me long enough to come to all this. so, maybe i ain't so smart. but, i will note that no one else seems to have arrived at a solution that is so, ... , well, just butt wipe simple, and inexpensive, as we say out here in these parts.
(wouldn't you just love to come visit, and listen to people talk this way? laughing. you probably think i just make all these little sayings up, doncha? well, we have lots of time out here, we love to talk, e.g., "bullshit," over coffee, and i know lots of people who really do talk this way. and, yes, it's fun.)
i think my solution, when you consider it from the dearth of resources available, and potential costs involved in doing it the conventional way, is, well, just pretty damned elegant.
we'll see how it all works out, if it does, and i will keep you posted.
and, if you've a hankering to try it out, give it a whirl. i don't own the rights to the .30/280 british, the people of england do. so, have at it.
john jay @ 03.13.2012
p.s. two observations. the .30/280 brit had a case shoulder about .449" in diameter, and my case will be about .454" in diameter when it is moved back along the 7mm-08 case the .255" it will be set back. that shouldn't raise any problems with feeding, as case design sees less & less taper along the cylander of the case as it evolves.
and, one other thing. the base of the case should not be materially affected by being move farther up into the die body. at a point just in front of the extractor grove, my 7mm-08/.308 winchester/7.62x51mm natos appear to be about .467" in diameter, and this compare to .467" in diameter at a point .255" in front of the face of the case. in short, the case is not going to be "squeezed" or "deformed" by being force farther into the die body.
and, one more "one other thing." i am gonna use hodgdon's h-335, or a powder of similar burn rate, such as h- and/or imr-4895, when and if this theorizing every comes to fruition. they seem to be used in low weight loads in the 7mm-08 and 7.62x51mm nato cases, and they should work.
it should work. laughing.
but, that is how you can make a .30/280 brit if you are so inclined.
p.s.s. did i happen to mention the rebated rim? to make the .473" diameter case rim of the 7mm-08/.30-280 british fit the bolt face of a 6.8mm remington spc bolt face, which is about .420" in diameter. piece of cake, no problem, at all. laughing.


friends, please keep in mind viewing this photo, that the cases and bullets are positioned within a set of dial caliper jaws, set at an opening of 2.260": this is the length of an ar-15 magazine, or clip as you might put it. the casing nearest the calipers is a .243 winchester, and the bullet beside it is a 130 grain sierra bthp, or match king. now, were the casing modified as discussed above in the article, the end of the case mouth would be just right at the juncture of the case neck and the sloping surface of the shoulder. and, the bullet would project out of the case, at that point, some .255" inches more than shown in the photo. in other words, the entire case neck would hold the bullet at its fullest diameter, before it begins narrowing down toward its tip. thus, the case modified as i propose in the article is sufficiently long in the neck to securely hold the bullet in place during handling, loading, and during the cycling of the action in firing. it also fits an ar-15 magazine/magazine well.
the .280 brit is sized as though made for the ar-15. or, perhaps eugene stoner and melvin johnson, of the johnson rifle, model of 1941 fame, may have designed the ar-15 around the .30/280 brit, perhaps the best "intermediate" infantry round ever conceived.