I found mention of the Gibbs loads in the two book set from P.O. Ackley and an edition of Wildcat Cartridges. I also had a book that covered the entire Gibbs line that I think was written by Roger Stowers.
I had a 25 Gibbs that I wore out and when I rebarrelled I went with 25-06 Ackley and am glad I did, I have the same muzzle velocity, same accuracy and can shoot factory 25-06 rounds which I couldn't with the Gibbs. I read that the 240 Gibbs was the most tempermental of the Gibbs rounds to load for but can't remember the reason. If you don't already own this weapon I would think about a 6mm/06 Ackley instead of the Gibbs, If you already own it you can find some loads in the books I mentioned above.
I'm afraid I already own this gun. It was given to me as a gift and I can't really change it right now. I know from reading that it is tempermental about pressures because of the extreme angle at the neck. I have two books ordered that I hope will have some informatation on it. One is the book you refered to about the Gibbs rifles. The only problem is it is out of print and I will have to wait 6 to 8 weeks before it arrives. I as just trying to get as much info about this wildcat as I can. Thanks for the reply.
You will need to find a powder that keeps the case almost full up to the neck, the biggest danger with the Gibbs round is getting too much air space in the case. I used a lot of H1000, RL 22 & 25 and H450, the H450 gave me the most velocity but they all gave me good accuracy of 1/2 inch groups or less.
You also need to monitor the case head expansion, with the Gibbs if its put together right you won't have any hard bolt lift or the other signs of pressure, if you don't get ten or so loads with a case because the primer pocket gets loose you are to hot. I used to buy my brass from Grayback Brass to save wear and tear on the barrel because if you load these hot and the barrel is chrome moly you will have the throat shot out in 500 rounds or less. When I shot out the second barrel in my 25 you could drop a bullet in from the chamber end and it would fall 6 inches past the chamber before the rifling would stop it. The gun would still shoot into 1/3 inch but you had to clean the barrel every five or six shots. If you come up with a problem let me know, I had a Gibbs in the family for 10 years.
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