cracker wrote:think your 500 would have abit more horse power then the .505gibbs but an interesting starting point non the less thanks for the reply.
The Gibbs will far exceed any 375 H&H wildcat, it has over 170 grains water capacity vs about 108 grains for H&H based wildcats. The reason it was loaded so low traditionally 2300 with 525 grain bullets was keeping things safe with old actions and cordite powder.
These days on a strong action you can push a 600 grain bullet to nearly 2700fps. The 505 is also the basis for the 408 chey tac ultra long range rifle.
As to actions, the Gibbs rim and case size will make it too large for all but a few. The most common conversions were done on the Brno602( CZ550 predecessor), CZ550( I did a 585 Nyati on the CZ550), the granite moutain arms action, the Montana action, and the big old M17 and P14 actions though these will need more work. The Rem and wby mkV actions will all be too small. Some had a concern with the CZ550 not leaving a lot of meat on the bolt once opened out, but it turned out to be fine. CZ was actually selling 505 safari rifles here for about $4400 up until a few years ago. The specialised scaled up long range rem700 clones designed for the 408 chey tac by Stiller and Lawnton will also accomodate a 505 Gibbs since the 408 is based off it. You could have fun with a detachable box fed 505 gibbs if you wanted.
Bob Devries at Kudu is excellent, but it will probably cost you more than you estimated, big guns attract a premium. I dont think you would get much change out 6k these days. Contact Bob first of course, I don't want to be spreading rumours that aren't true. The other gunsmiths that can do it are Anthony George in the NT and John Clapham in the blue mountains. If you want their contacts let me know. Remember you also have to figure several hundred dollars for dies in this class and cases may be $5-8 a piece so start up costs may be a 1k more than you were expecting.
There are cheaper and easier options for a 50+ cal. Getting a factory CZ550 in 416 Ribgy if you can find one its basically rebarrel to the 500 A-square or 510 wells( both essentially the same .510 calibre wildcat) as the 416 Rigby has the same dimensions as this whole family( 416 rigby/416 weatherby, 450 rigby/460 weatherby, 475 A&M, 500 A-square, 530 woodleigh, 550 magnum). The 500 versions will beat 460 weatherby power by at least 10%, you will be pushing 600 grain bullets to almost 2600fps. They can use the full range of 500 jeffery bullets( another old elephant gun like the 505 gibbs) which woodleigh produces. The 550 magnum is probably the most bang for the buck. Its a .550 barrel on the same gun, its the largest diametre the weatherby magnum case head size can accomodate. This gun will push 700 grain bullets over 2300fps. Anthony George in the NT has reamers and barrels I believe.
If you want to go larger than that , there is the 585 nyati, which is a unique case size , slightly fatter and shorter than the 505 gibbs. Its needs the same actions mentioned above for the 505 Gibbs and similar extensive gunsmithing as well. It will push 750 grain bullets to 2500fps, over 10,000ftlbs energy. After that is the 600 overkill, which is about the largest you can do off a standard magnum boltaction, and it will push 900 grainers to 2400fps. I believe Anthony George has the reamers and barrels for this as well. These are a fair bit of work to do, like the 505 gibbs as they are into that giant oddball case size.
Off bolt actions and onto the Ruger no.1 single shot, it can also accomodate most of the old elephant gun cartridges too. The 577 nitro is considered the limit, it is not large enough for conversion to 600 cals.
Above that you are into customising 50BMG actions or building custom single shots, for which you can go all the way to 700 nitro, though price will be really climbing as well, 10k level.
My bods too screwed for the big stuff these days. If I was going to get into the big stuff and just wanted extreme, convenient, relatively low cost power I wouldnt go for the 505 gibbs as its more work to do. Id get one of the weatherby case head wildcats like the 500 A-square. Easier gunsmithing job, pretty much a re-barrel, keep the old stock, maybe add a pound of two of epoxied lead shot into it, there are more bullet choices in 510, you can use light jacketed blackpowder bullets for blowing up light game, true elephant gun bullets, and some blokes even single load 50BMG pointed bullets in them too. The only inconvenience is you may need to neck up and fireform brass using 460 weatherby magnum cases, unless someone is bringing them in standard.
You'd get the 505 gibbs more if you wanted the historical angle, since its one of the oldies of the safari era, or if you wanted to chase more power, since its cases are about 30 grains higher capacity than the weatherby wildcats. Personally I don't think you'd ever use the power, unless you are building a 16lb rifle any loads near 2600fps with a 600 grain are going to be graphic recoil with either case. As the gibbs has factory brass and there still may be some rifles in it kicking around that might be an advantage as well.
Personally if I was going to the trouble of getting the Gibbs, for the same cost I would probably jump right to a 585 Nyati on a cz550, or actually a 577 nitro on the ruger single shot.
So rehashing some options
1. Cheapest and easiest. 375H&H case head. about 90-100 grains capacity. 375, 416 taylor, 458 win, 416 rem, 458 lott, 470 capstick etc. usually just a rebarrel of each other, dirt cheap brass, tons of actions.
2. 404 jeffery or its wildcats. This includes the remington ultramags which are based off the 404 jeffery. These will usually have a bit more capacity than the 375 case head wildcats.
3. Weatherby Magnum or Rigby case head size(basically the same). 130-150 grains, signficant jump in power, still reasonably economical re-barrels if you can find a CZ550 rigby donor or if weatherby still does 30-378 or 338-378 wby's on MkV actions(they used to sell these for just a couple k, you could rebarrel to 500 a-square, though adding weight to the stocks would be needed). Calibres all the way up to 550 as mentioned. Most things firing a 338 lapua should also handle these case sizes as its based off the 416rigby too.
4. 505 gibbs size case head, including the 408 chey tac and its wildcats. usually 150-175 grains capacity. The largest magnum actions, also special long range actions designed for the 408.
5. The ultra-large bores, 577,585, 600 etc. , anywhere from 180-220 grains capacity cases. The largest magnum actions.
6. 50BMG sized projects. 12 ga from hell, 700 nitro, 577/700., 220 grain+ capacity cases.