500’s revisited

Good afternoon everyone,

I have been planning a new 416 Rem Mag build with a GMA action customized to my specs to replace my Win Model 70 Safari Express as my primary carry. This is in motion and going along GREAT….. however….. I’m left feeling the NEED for a 500 caliber of some kind to fill the gap.

I’ve had two different Hannibal 500 A-Square rifles. The p17 actions worked well, but not my favorite design/feel. The stocks worked well to absorb recoil, but much better ones can be made to accommodate the rifle and carry better. I love the 500 A-Square caliber. Easy to reload, easy to source bullets. Biggest negative about the rifle is there being NO properly headstamped “500 A-Square” brass anywhere to be found. No one makes it and enough pieces don’t exits among private owners to try and gather up so you could take it on hunts in Africa where it’s meant to be. If you can’t get the rifle’s ammo into the country, it just isn’t worth it whatsoever. Unless I could get or find 250 pieces of proper headstamped brass for the 500 A2, I have pretty much given up on the cartridge.

I’ve grown fond of the 505 Gibbs in the last year. Brass can be found and bullets are easily sourced as well. Plus I can just as easily get a GMA action for it and make it the twin to my 416 Rem Mag.

Who here has owned or currently owns a 505 Gibbs and what are the pros and cons of it? Who has actually hunted with it and has seen its capabilities?

And when you tire of the 505 Gibbs you can upgrade to a 585 GMA

Where can you find brass for Gibbs? I have found Woodleigh bullets at Raven Rocks but brass has been unobtanium.

I have owned and hunted with a 505 Gibbs.

Pros:
- It's obvious... but it hits like a truck! The penetration and wound diameter are IMPRESSIVE, especially with the 570gr A-frames I was using.
- If the gun is properly made, the recoil is fairly easy to manage.

Cons:
- .505" bullets aren't as common as .510" bullets.
- The cases have entirely too much capacity. This can make it tricky to get good accuracy at lower velocities.
- The size of the case makes it hard to keep them in the magazine. Most 505 Gibbs rifles are very prone to having cartridges pop out when the action is cycled too aggressively.
- Now that Jamison brass isn't easy to find, brass is rare.

It’s a shame that nobody has produced a run of un-headstamped .460 Weatherby brass. Think cylindrical magnum “basic’ brass, only on the .378 / belted .416 Rigby case.

Spartan5 said:

Where can you find brass for Gibbs? I have found Woodleigh bullets at Raven Rocks but brass has been unobtanium.

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Bertram brass makes regular batches. And can be found from multiple distributors. There have been rumors of Bertram brass varying in quality batch to batch. So far, for other calibers, I’ve found this to be far from true. I have also ordered brass directly from Bertram by speaking to Bruce. He can accommodate and is more than happy to do so.

As far as bullets go, I will only use and depend on Cutting Edge Bullets like I do for my other calibers.

Certus said:

And when you tire of the 505 Gibbs you can upgrade to a 585 GMA

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Anything is possible, but probably won’t re-chamber once build is complete

analog_peninsula said:

It’s a shame that nobody has produced a run of un-headstamped .460 Weatherby brass. Think cylindrical magnum “basic’ brass, only on the .378 / belted .416 Rigby case.

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Agreed. I’ve only ever used Norma 460 Weatherby brass for the 500 A2. It works flawlessly and I’ve never had any sort of issue. Just runs risk of not getting past customs and I don’t want to chance test my luck. There are a few jewelers that could custom engrave blank headstamped brass, but none has been made to date. That could definitely work though.

RootballExpress said:

Anything is possible, but probably won’t re-chamber once build is complete

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Rechamber? Heavens no. A new GMA build

Edit to add, and be back on topic: anyone I’ve seen who wants a .505 Gibbs, no other cartridge (even mirroring ballistics) will scratch that itch. Must be something to do with that unique bore and massive case. Go the 505 if that’s what the desire is.

No headstamp feels much more likely to get through than a mismatched headstamp.

Why not just settle for the 500 Jeffery? It sounds like the 505 Gibbs after everything has been sorted out.

The answer remains .550 Magnum with a lifetime supply of brass

I disdain Bertram brass do much that I moved a .425 WR on down the line. I would seriously recommend a .458 Lott or .450 Rigby. Although I love the big stuff, there is nothing magical about 1/2”+

I have limited experience with the 505 Gibbs, I’ve fired no more than 20 shots out of two different rifles. I’ve fired a couple of hundred rounds of 500 J out of 4 or 5 different rifles. I reload for the 500 J.

I’d go for the Jeffery purely because of projectile and case availability. Of the two 505’s iv shot one had a feed issue with the last shot. The other worked well. Recoil no different than the 500J’s.

Of the 500 J’s the Big Sako’s can be a bit sticky when working the bolt. But otherwise no issues.

I’ve shot nothing but paper and steel with both the 505 and 500 cartridges. I seriously doubt that any thing that is shot will either could notice any difference.

I’m planning on shooting some buff next year with my 500 J. I love shooting the thing….fucked if I know why ….

R eight said:

I have limited experience with the 505 Gibbs, I’ve fired no more than 20 shots out of two different rifles. I’ve fired a couple of hundred rounds of 500 J out of 4 or 5 different rifles. I reload for the 500 J.

I’d go for the Jeffery purely because of projectile and case availability. Of the two 505’s iv shot one had a feed issue with the last shot. The other worked well. Recoil no different than the 500J’s.

Of the 500 J’s the Big Sako’s can be a bit sticky when working the bolt. But otherwise no issues.

I’ve shot nothing but paper and steel with both the 505 and 500 cartridges. I seriously doubt that any thing that is shot will either could notice any difference.

I’m planning on shooting some buff next year with my 500 J. I love shooting the thing….fucked if I know why ….

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A 500 is definitely adequate for buff. Other larger 400's may be too, I have no experience or data to say, but I can say that 500, shot well, is enough. Why? My PH uses a 500J and has had to stop many buff. They all stopped.

R eight said:

I have limited experience with the 505 Gibbs, I’ve fired no more than 20 shots out of two different rifles. I’ve fired a couple of hundred rounds of 500 J out of 4 or 5 different rifles. I reload for the 500 J.

I’d go for the Jeffery purely because of projectile and case availability. Of the two 505’s iv shot one had a feed issue with the last shot. The other worked well. Recoil no different than the 500J’s.

Of the 500 J’s the Big Sako’s can be a bit sticky when working the bolt. But otherwise no issues.

I’ve shot nothing but paper and steel with both the 505 and 500 cartridges. I seriously doubt that any thing that is shot will either could notice any difference.

I’m planning on shooting some buff next year with my 500 J. I love shooting the thing….fucked if I know why ….

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To be fair I’ve often heard the 500 Jeffery is harder to get to feed reliably, so would more likely just depend on the maker than the cartridge (as with any rifle cartridge).

Kevin Peacocke said:

Why not just settle for the 500 Jeffery? It sounds like the 505 Gibbs after everything has been sorted out.

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You got it the wrong way round . 500j jams often . I have experienced big jams with a very expensive 500j as did the very famous gun writer owner who was trying to sell it to me . No problems getting bullets ( Woodleigh) or brass ( Norma and Bertram ) . No fillers required if using AR 2213sc powder . And of course Norma make PH ammo with 600grain pills . Whatever the 500J does the 505 does better . I have to 505s a custom with a Dumoulin action and one with a double square bridge GMA action . Love them .

I have shot a 500 A2

That was good and cheap to make of .460Wby brass with reforms

For double rifle shooters the 500NE is a very impressive cartridge. A 570grain bullet at circa 2150fps takes a lot of stopping . It is worth noting the Norma PH ammo with 570-600grain bullets for the 500J and 505G are only replicating the 500NE performance .

For a couple of seasons I hunted with a beautiful V.C Roundbody double in .500 N.E.
A stunning rifle that shot incredibly well and I managed to pull off some spectacular shots with it.
It really left an impression on buffalo.
Unfortunately for me I just couldn't come to terms with carrying that much weight around every day, a situation that was compounded when trophy capes and heads had to be recovered far from anywhere a vehicle could reach. In the end I sold it to someone who would appreciate it more than me.

For the last 5 years of my guiding career, and right up to current day, I hunt buffalo with a M70 chambered in .500mdm, the brainchild of our own forum member Michael458.
It's not .505 nor .510 but a true .50cal, necked up on the .375RUM case.
I've used this combo on many buffalo, and other bovines, in varying situations and it's absolutely stunning in performance.
Packaged in a relatively light, just over 8lbs, and short platform it's a pleasure to carry all day and performs like a champion in the heat of battle.

One day, after witnessing me sort out a couple of problem bulls that were giving the local community some issues, my Elder Traditional Owner, referencing my rifle, said "him make-em sit down real quick, Eh".

I have a 505 Gibbs built on a GMA action with integral 1/4 rib, swivel band and recoil lug all milled from an oversize barrel blank…the milling done by GMA as well. Ryan Breeding chambered and built the rifle. It’s a plain French grey coated, synthetic stocked gun that Ryan put together for Marc Buchanan to take to the Canadian arctic and hunt polar bear…which he successfully completed and was one of his Big Bore Production videos back in the day.

I’ve only had it about a year and shot only paper thus far.