I will have chambering reamers from Dave Manson in hand, in less than two weeks! Yes, reamers! Plural! I have been encouraged to make a family of four or perhaps five, cartridges based on the 505 Gibbs Basic. There will be cartridges in 550, 510, 475, 458, and maybe a 416 on the 3.15" oal Gibbs case. The first two calibers to be done will be the 550 and the 475 calibers. These two reamers will be used to chamber for those two cartridges, and then sent back to Dave to be sharpened/cut to 510 and 458 Gibbs wildcats. Depending on how testing goes, there may be a 416 Gibbs to finish out the lineup.

In an attempt to do this on a budget, and to give Tomo577's new/old single shot a true test; the Wickliffe 76 action will be utilized for the program. It lets me order 1 3/8"x 30" long cylindrical barrels and fit all four or five to the action. It thus requires just that action and stock to do all of the work, saving me several hundred dollars and several months time. The W76 is based on the Stevens 44 1/2 action, which is a true takedown. I intend to use my original 44 1/2 to model that system on the W76.

I have had PM's asking about a rimmed case, and we will address that early next year. A rim would give a new .62 caliber case to play with, and if done right would allow all of the cartridges in the lineup the option of a rim while using the same set of dies for either version.

My friend in the Hornady Custom Shop has the 550 dies off for heat treating as I type. Dave will be sending him the reamer specs for the 475 on Friday, and I will hopefully have them before Christmas. He will also get the specs for the 510 and 458, so we can likely expect them by early 2007.

All that is left to do now is acquire some bullets to test with, and design some RFN cast bullets in appropriate weight for caliber. My thought is that the bullets will run 15-20% heavier than jacketed, since the leading in big bores starts around 2200-2300fps, depending on specific caliber. 800-850gr in .550", 600-675gr in 510, 500-575gr in 475, and 500-600 in .458". I personally like the idea of a 450-475gr .416" bullet. The input I get will determine final weight and RFN shape, since the notion to take any and all of them to Africa for DG hunting appeals to me. For penetration, nothing coppercoated out performs hard cast.

best regards, and have a joyous Thanksgiving with family and friends.



Rich
DRSS in 2007

good stuff rich

please take pics and i'll post them to chronicle the project from start to finish. seeing the pics will give this thread somthin to look at

quote:

Originally posted by Idaho Sharpshooter:
there may be a 416 Gibbs to finish out the lineup.
I personally like the idea of a 450-475gr .416" bullet. The input I get will determine final weight and RFN shape, since the notion to take any and all of them to Africa for DG hunting appeals to me. For penetration, nothing coppercoated out performs hard cast.
Rich
DRSS in 2007

416 450grn gives a SD of .371 & the 475grn a .392 SD. Holy spit!! They're friggin' drill bits!

yeah,
but with a standard twist they will probbly bounce off of large game animals. 400gr at 3000fps.

Rich

we do have a sort-of update. As some of you know Jeffe and Neal Shirley are doing a flanged version of the 550 Magnum. Interesting coincidence: at the same time George Gibbs was trotting his 505 out for the boltgun trade, the .577/.500 Magnum NItro Express appeared for double and single rifles. The cases are soooooo close dimensionally it it hard to imagine that it was happenstance. 3gr of water and .005" diameter bullet difference .

You all know where this is going, right...? As soon as I get the dies for the 550 from Hornady I am going to FL size a 577/500MNE in the 550 Gibbs die and see what I have. Like, the 550 Gibbs rimmed.

Just waiting around for the stuff to arrive...

regards,

Rich

Hi Rich,
You will be impressed with the .475-560 grain bullet penetration. I've shot them in my 470 Mbogo at 2350 fps as well as the Bridger 540's at 2400fps. Both penetrate like crazy. I don't know what velocities your thinking about but the Gibbs case does have more volume.
Take good care,
Dave

Dave,

as hot as my shoulder can stand. Maybe as a top end 2600+fps if the recoil is liveable.
This is as much a fact-finding expedition as any thing else. What are the upper limits for recoil tolerance as far as MV and ME? 200gr h2o capacity. Yours' is more practical, but I am just too curious to let it go.

Rich

You're probably getting into recoil levels where a muzzle brake begins to be essential. As much as I hate them in general, they can be only way to "enjoy" these kinds of recoil energies and high recoil velocities.

quote:

Originally posted by Idaho Sharpshooter:
Dave,

as hot as my shoulder can stand. Maybe as a top end 2600+fps if the recoil is liveable.
This is as much a fact-finding expedition as any thing else. What are the upper limits for recoil tolerance as far as MV and ME? 200gr h2o capacity. Yours' is more practical, but I am just too curious to let it go.

Rich

Sounds like you need to take a trip to Lost Wages Nevada and visit RGB.

.366 Torque,

Rob's toys are waaaay over the top for this cowboy from Idaho. His dogs all eat at both ends!

Rich

Update:
the UPS babe just played santa claus at my house! I was hoping for halloween (trick or treat?), but Christmas is even better this time.

Hornady shipped my 550 Gibbs dies!!!
Dave Manson is done with the 550 and 475 reamers, and will ship shortly.
Then I can cut a form and trim die and get some cases to show off.
Bottom line, I expect to be shooting this rifle before February 1st.

regards,

Rich
DRSS
NRA Life Member

congrats on the next stage rich...

giter-duuuuun!