My RSM may have a monster infection.

Ardent

Ardent

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Something large and grotesque may grow inside it.

I'm having a hankering to rebore my RSM, I'm not using it after I picked up the double but have a lot of history with it, and would like to make it sassy again in my eyes. Want a truly overkill monster rifle, cannot be a modern chambering like the TRex, I like classics.

It is a proper magnum action as you all know, and I'm debating the following:

.500 Jeffery
.505 Gibbs
.577 Nitro Express (odd, yes, being rimmed but considering the challenge, I recently acquired a .303 Mauser from a good Brit maker that runs like a top and it's convincing me).

What else would you short list?
 
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So you bought that Greener mauser in .303 did you? Nice rifle. As for the RSM, how about a 450 Rigby ? Otherwise a 505 would get my vote.
 
Here's a thought. How about a .375 Cheytac? Oh, its not very traditional but it have a .505 in its ancestory. You can rebore to .505 later.

I have a plate at 500 yards that is 1" thick and 36 X 18. If my calculations are correct it should weigh 183 pounds. It hangs on 2 4" transport straps that semis use that are doubled over so the 1/2" bolts with 1" washers go through 4 layers of webbing. With its weight a .300 magnum won't even make it wiggle at that distance.

It lasted one shot from the Cheytac with a 350 grain SMK. One hit tore that 180 pound plate right off of the webbing on one side. It didn't quite go through but almost did and it did raise a dimple on the far side. Remember this is at 500 yards. I wouldn't be scared to hang my truck from that webbing.

Naturally, my thoughts went straight to a sporter in that caliber.:D
 
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If rimmed were on the menu 450/400 nitro 3 1/4". Classic and recoil shouldnt be that bad other wise I'd go 505. As a plus the barrel stamping can be modified to read sos... cuz its Gunna kick the life out things at both ends lol

Might get more responses in the rifle section though
 
Sheesh how did I end up in shotguns? Late night and scotch, calling a friendly mod would appreciate the move. That's amazing performance Dogleg, and sounds like a mean cartridge that would be an easy in between. Pretty set on going straight to a classic however, I want to experiment with the true big bores on game and see if there's anything to them. It's also time I bump up my recoil threshold, I do like the .500 Jeffery because of the .510 bullets. Brybenn I like the .450/400s but they are just not big enough for the cartridge class I'm after, want to be over .50.
 
Of what I know offhand for 50 Cal dangerous game rifles ill list.

12.5x70 mm schuler , I think I spelled it wrong
50 tac. It's a Cyrus that's 510 instead of 500 on a 416 Rigby case but if I remember right it's short.
585 nyati. Hard to get a better cape buffalo round. It's named after them
450 Rigby. Not a 500 but I wanted one. I went 458 wm cuz I'm not rich
510 nitro
500 Jeffery
505 Gibbs
495 and 500 A square. Both use 510 bullets on the 460 weatherby case
Then there are the 577s but I don't know how well they'd work in a rsm

Either way you go I hope you post pix of the build thru to completion
 
I was actually startled when a well known member of the site just offered his .505 Gibbs converted RSM for testing, long term, I'll do an article on it. It's dam well too generous and all I'm concerned about is how to return the favour. This monster cartridge exploration will come to fruitition a lot sooner than I anticipated.
 
It begins, found a hundred Barnes 525gr solids.

39F60B37-1649-4EC7-9202-561645EDB256-10045-0000097383BCA414_zpsd77f5c78.jpg
 
I remember when you had your RSM on the EE and I thought about picking it up and doing a 505 Gibbs on it. I saw one done by Hamilton Bowen years ago when he did such things and I took my Gibbs round from my collection and slipped it into the magazine of my Rigby RSM one time in a fit of madness. It fit which lead me to almost liberating you of your spare. As such its only fair that you send your monstrosity out here to dummy a GSD-sized deer.
 
Haha noted, well if that spare RSM had been of been a couple serial numbers different I'd have kept her, it and my favourite one had two serial numbers in between them. Were they sequential I never could have broken up the pair. Well I have enough stuff for 160 rounds of .505 Gibbs 525gr solids, looks like with some great good luck and a lot of help for a member here I'll be wrapping the first gong around the post soon.

 
Don't dink with your RSM. If our need a project, buy a different one to rebarrel or pick one up in .416 or .458 Lott and run it as is. In the end, a .375 is far more useful than the true big boys, and it would be a shame to bugger something with lots of history with you.
 
It just grows, and trouble is I'm ending up with too many guns with personal histories, several of them .375s. It would actually gain a shimmer again in these eyes and earn a place in the first line so to speak. I'm transitioning to my guns just being tools, I like good ones, really good ones at times, but in the end they work for a living and need to remain interesting. I'll see how I enjoy the generous lender's .505 RSM and go from there on plans. I do believe the .577's out as it ought to be a double on consideration.
 
Dogleg said:
Here's a thought. How about a .375 Cheytac? Oh, its not very traditional but it have a .505 in its ancestory. You can rebore to .505 later.

I have a plate at 500 yards that is 1" thick and 36 X 18. If my calculations are correct it should weigh 183 pounds. It hangs on 2 4" transport straps that semis use that are doubled over so the 1/2" bolts with 1" washers go through 4 layers of webbing. With its weight a .300 magnum won't even make it wiggle at that distance.

It lasted one shot from the Cheytac with a 350 grain SMK. One hit tore that 180 pound plate right off of the webbing on one side. It didn't quite go through but almost did and it did raise a dimple on the far side. Remember this is at 500 yards. I wouldn't be scared to hang my truck from that webbing.

Naturally, my thoughts went straight to a sporter in that caliber.:D
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You just need a lighter piece of AR-500 plate. When you whack it the plate may flip up and over but you won't penetrate it and the weight of the plate won't rip the harness off. ;)
 
Ardent , you have an itch that must be scratched so just go ahead and do it. I tend to be pretty pragmatic do this type of stuff doesn't interest me much but if I *was* so inclined I would put my pragmatic side to work and make my choice based on:

* What will work in my action without too much trouble/work

* Brass availability

* Bullet availability

Custom guns in odd chamberings can be a nightmare, so that is #1. Rifle won't work without brass so that's # 2. Rifle won't work without bullets , but bullets seem easier to find /make than brass so that's third on the list

Very rare cartridges have their own mystique, but it's more fun to have easy to make ammo to shoot
 
I actually agree on ammo availability, especially if I'm going to travel with it. The only hunt I have in mind for a .505 is South African Rhinoceros, and I can have my PH land 20 cartridges in hand, in country, just incase. I was surprised how easy it was to source .505 Gibbs components, I bought 100 Barnes .505 solids at Wholesale Sports off the shelf, and 60 rounds factory ammo from Elwood Epps.
 
Gatehouse said:
You just need a lighter piece of AR-500 plate. When you whack it the plate may flip up and over but you won't penetrate it and the weight of the plate won't rip the harness off. ;)
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Trouble is, I couldn't beat the price. Free is my favorite number. I've got a sheet of 1/2 AR500 on order, it comes to $1200 with a few cuts thrown in. I've shot 1/2 AR500 at 500 with the Cheytac; it doesn't mark it but when I smack that 12" plate it knocks the stand down instead. I'm going to experiment with re-bar bent into hooks instead of the webbing.
 
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