Anyone have info on the 30 Gibbs? Have an 06 barrel I was thinking of chambering to 06 AI but someone emailed me with the 30 Gibbs idea. It has to be similar to the 300 Hawk. Anyone have any knowledge, data, experiences with the Gibbs? Thanks.
Bob Hagel did an article on the 30 Gibbs years ago and his report that there was only about a 50 fps improvement over the 30/06 when pressures were held the same. Basically Rocky Gibbs moved the shoulder forward and reduced the neck length to about .215". Hagel found that this only increased the volume of the case by 5.8 grains of water when using a Hornady 180 grain flat base bullet seated to the same depth in both cases.
He sums up the article with: "To sum up the performance of the .30 Gibbs cartridge, it will produce about 50 fps more than the .30-06 with the same barrel length when both are loaded to approximately the same pressure levels. If you are looking for high velocity from a .30 caliber cartridge, you'll have to go to something like the .300 Winchester or .300 Weatherby cartridges..."
I do have this article and can get you a copy if needed. It has about 25-30 loads for the 30 Gibbs and case forming instructions. Rifle rechambering and all ballistic information are included, as well as a bit of history of Rocky Gibbs and his line of cartridges.
I have played with the .270 Gibbs for several years. It is an interesting concept and I like the cartridge well enough to have chambered 3 rifles for it, but it's not for everyone.
I remember the hagel report very well and I would ask him how it is possible for the Ackley imp with a 2% increase can gain something like 150 fps while the Gibbs at nearly 6% increase can only gain 1/3 of that. Also note that hagel had only his eyes to check pressure. Could he have stopped too soon?
I have a Mauser that I am going to rebarrel and think that I have decided on the 30 Gibbs. I have compiled quite a bit of information on it. It looks like with the best loads you should be able to reach 3000 fps with a 180 gr. bullet out of a 26 inch barrel. If you would like, I can send you copies of what I have.
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