Interesting thought. Would be pretty identical to the 6x284 which a few shooters load for. I have a 6mm bartlien barrel in 6CM with only a couple hundred rounds on it I’ve thought of a 6x284 build with. My 6.5x284 dies would work I think with 6mm bushing. Lapua brass is available to downsize too.
It's doubtful that SAAMI or CIP will make this cartridge legitimate. It's been around for a long time and has been ignored for that length of time also.
If these longer 6mm cartridges interest you then take a look at the .240 Weatherby or the wildcat .240 Gibbs which has a larger case capacity yet. I shoot the .240 Weatherby and have owned/shot a .240 Gibbs as well. Longer barrels and slower powders work quite well. I did build a 6-06 Ackley Improved which is fine but the .240 Weatherby is slightly more convenient with similar performance.
I found this article about Rocky Gibbs and his cartridges. Fun reading!
Monday, August 17, 2009
Rocky Gibbs And His Cartridges
Mannolis Aamoen Gibbs was a Texas boy who moved from dust bowl Texas to California, not being one of the "Okies" who showed up broke and starving, though. Funny how during those days anyone broke showing up in California was an Okie, even those from the Dakotas and Iowa. At any rate he didn't go by busted down Model T but by train, in the passenger cars no less. Young Mr. Gibbs wanted to become famous and thought his moniker was a handicap. Going through a rather tall mountain range he asked what they were called. The Rockies. He became, on the spot, a moving spot since he was still on the train, Rocky E. Gibbs.
This is a sort of a review of the "book" on disc I got for subscribing to Handloader Magazine. I put book in quotes because it's more of a booklet on disc. I had visions of being offline for days while I waded through a several hundred page tome, this whole thing had 64 "pages" plus a short preface. Still, it was an interesting and informative look at a slice of American firearms history.
Settling in Richmond, California he became a hunter and, from there, a shooter. Most nonshooters do not realize how many hunters are not much in the way of shooters. A powerful lot of hunters can make a twenty round box of cartridges last years.
Rocky, because a case of Typhoid Fever robbed him of the sight in his right eye, had to learn to shoot as a southpaw. Wanting to be a good hunter he decided to become a good shooter and joined the Richmond Rod and Gun Club, long gone due to excessive urbanisation. This club had a type of target shooting contest I've never heard of before and I've heard of a lot of different shooting contests. there rifle matches were slip into two halves. The first being a series of smallest groups at one, two, three and four hundred yards, and the second smallest groups at one hundred yards and then smallest group and least drop with that hundred yard zero at four hundred yards. The book didn't quite tell me how that was laid out, what percent of the score was for each group and what for least drop but it had to be some significant part for the least drop.
Rocky started out with a .270 Winchester in that old Remington 721, then having it rechambered to .270 Ackley Improved. He then ran into the same problem that plagues the Remington 700 with high pressure loadings to this day, an itty-bitty little extractor that sometimes tears out of the case rim, leaving the rifle tied up until a cleaning rod is fetched and the case poked out from the muzzle.
So he got a Winchester Model 70 and that solved that problem. Rocky didn't really love the Ackley Improved line of cartridges, though. He thought they were close but no cigar. The Ackley Improved was developed by Parker Ackley during the 'tween the war period. A cartridge like the .30-06 or .270 has a gently sloping shoulder and quite a bit of body taper. Ackley (and several other gunsmiths) discovered that if one took and made a new chamber reamer they could make a much sharper shoulder and eliminate most of the body taper. Then just by firing a factory cartridge in the new chamber you could make a "new" cartridge with a significant increase in powder capacity. Like a car engine, the more capacity, the more power. Plus, the straigher taper does allow loading to higher pressure without increasing the bolt thrust or the pounding that those bolt locking lugs take. Just trust me on this, the reasons are too long and complicated to go into here.
Anyhow, every bottlenecked rifle cartridge in America went through some form of improvement. Parker Ackley, had his, A feller named Mashburn up in Oklahoma City had his, someone named Durham, the ICL line and Roy Weatherby all made them. Many were made by just blowing the cases out, others were necked down to smaller caliber or up to larger caliber.
The thing to remember, though, is an Improved cartridge will also shoot standard factory ammo. You would lose a slight amount of velocity because some of the powder gas that would normally push the bullet would, instead, blow the case walls out to the new shape.
When Rocky decided to make his own line of cartridges, they were not regular improved cartridges, he didn't just blow the walls straighter and make a sharper shoulder, he also moved the shoulder forward. His cartridges are famous, some say infamous, for their short case necks. There is the same complaint about short necks with the .300 Winchester Mag. Nobody is sure persactly why these short necks are such a problem but some folks just don't like them. I guess those short necks won't hold the bullets straight if you carried some ca'tridges loose in your pants pocket and rolled down a mountain or something although I suspect if I were rolling down a mountain the straightness of bullets would not be high on my list of worries. But, that's just me.
At any rate, instead of being able to shoot factory ammo, one has to go through some from of hooraw to form cases for a Gibbs cartridge. The simplest way is to pull the bullet and then reseat the bullet far enough out to engage the rifling. This will hold the base of the cartridge back against the bolt face long enough to blow the shoulder forward. We can save the cost of a bullet by necking the case up a bit and then necking just the tip of the neck down again, enough that that casehead is held firmly against the boltface. Then we fire it with a dose of faster burning pistol powder, the case filled with grits or cream of wheat and stopped with toilet paper or wax. I knew an old guy who used to shoot rats in his barn with wax out of his fireforming rounds.
Rocky had another method of making his cases, though. It was the first product of the Gibbs rifle company, in 1953. He used a sizing die for his cartridge, with the neck expander and decapping pin removed and then a tight fitting plug to go in the case neck. He would then put an inert primer into the empty case, fill the case with light oil, insert the plug and whack it with a hammer. this would, after a couple of whacks, blow the case out, then he'd pour the oil out and go to the next case. Now I haven't ever done this, just from reading of it, I wouldn't want to do this while wearing a nice white suit. Or do this in the house.
In addition to his line of wildcat cartridges Rocky experimented with front ignition with his cartridges. He wasn't alone in that, either. The most famous of those fooling with front ignition were Charles O'Neil, Elmer Keith and Don Hopkins. Every gunny knows of Elmer Keith.
This was called duplex loading. In addition to a tube threaded into the primer flash hole to carry the flame up near the front of the powder charge this method of loading also used a smaller charge of faster burning powder at the casehead. I never fooled with these and, now that I'm very near the end of my shooting career, I will not. It is very interesting, though. In our world of fast food and microwave meals I seriously doubt that very many will bother with this technique today. It is easier just to get a gigantic case and use gobs of extremely slow burning powder.
Still, the idea of front ignition duplex loads is intriguing. The claim for these loads is higher velocity, longer barrel life and reduced recoil.
The higher velocity claim is true, the things against this are fairly simple. One, these loads look like a pain in the patootie. First we must go through the hassel of threading these little tubes and the cases, then inserting the tubes. We must then modify our sizing dies for handloading these cartridges. Then we have to find the right sized drill rod and temper it for decapping the fired cases. Then we have to figure out a way to keep that fast burning powder from getting into that flash tube.
But wait! There's more! After doing all that we must then use a powder for the main charge that will be sightly compressed when we seat the bullet. If the powder charges are not solidly compressed so they can't shake around we can get a KABOOM! and be picking little pieces of rifle out of our hides, if we're able to pick.
Still, it's interesting. The idea that barrel life is longer comes from the lack of "sandblast effect" of the unburned and burning powder granules hitting the barrel. Lighting the fire from the top means the burning powder gasses force the rest of the powder to stay down, at the same time forcing the bullet to go up. This is only logical, just as the conventional priming would have the gasses start at the bottom and force everything up.
This is where that faster powder comes in. The slow powder has already been burning, the gasses have already been pushing the bullet a bit down the bore. This, in effect, makes for a great big "case". Like the od black powder cases used with modern powders, that big combustion chamber means we need a fast powder to make lots of powder gasses, quick. So, in duplex loading we have this fast powder to give another boost in gasses just as the pressure is going down.
This means, when it works right, a longer peak pressure curve. So we get higher velocities. The lower recoil for the same velocity is also simple, in conventional cartridges the way to increase velocity is to make the case larger and use larger amounts of slower powder. Since heavier weights of powder increase recoil (for every action there is an equal and opposite action) the front ignition duplex loads really work.
Trouble is, this is a mid-Twentieth Century idea in the 21st Century. Even then few were interested in the idea. Conventional handloading of ammunition is actually pretty simple. Recipes for loads abound. Anyone willing to follow directions can load safe effective ammunition. There are few such recipes for the front ignition duplex loads.
Rocky's business never really recovered from the fire that destroyed his Idaho house. Then his health started downhill. Then his sons decided they were not interested in staying in the business after they grew up. Rocky died in 1973 and that was near the end of that kind of experimentation. What a shame.
I built a 6-06 on Rem 700 action and a 26 in, 8 twist Brux sporter contour barrel. Was amazingly accurate with Berger 105 Hybrid's at 3300 fps. The down range ballistics were pretty darn impressive. Shot mostly steel, but also killed a few whitetail and hogs. Pretty swift killer. Was also fun to shoot and easy to load for. 25-06 brass and one pass through a 6-06 die was all it took. Wish I would've kept it. I've since picked up a 240 Wby though, which is essentially a ballistic twin to the 6-06.
Don't foresee anyone commercializing the 6-06. It would've happened by now given it's age.