Just started doing the sums on a new rifle. Maybe. Looking at something rather large that would be a step (or 3) above my 416 rigby in a Ruger RSM. So I started looking at various 50 cals and figured that they are all "adequate" in power, all will use the same projectiles etc so are reasonably similar. I am considering calibers like 500 jeffery, 500 a square, 495 a square etc.

Reading Terry wielands book "Dangerous Game rifles" he mentions the .495 A Square as a Brilliant design for reliable feeding. He notes no real shoulder (there is a ghost shoulder), pronounced body taper and straight case as features for great feeding.

Does this make sense? I could understand these features are good for extraction but are they also good for chambering? I would have thought extraction problems could be largely managed with reasonable chamber pressure and rifle maintanace. This would make chambering a cartridge more of a significant issue.

So would a bottle neck caliber be more forgiving during chambering vs a straight wall case? I know that a properly built rifle should feed...... What i am talking about is the inherrent ability (if any) of a caliber to feed well.

Because at this early stage I am not particular as to exactly what caliber for this rifle I thought reliable feeding might be a way of trying to narrow down the field. To this end I thought I would ask the learned folk here!

Thanks for taking the time to read this post.

Best,
Marlin45

Frankly, the 500 Mbogo and the 500 AccRel are likely the 2 best feeding .510 out there. they were designed to do that.

there's a 500AccRel reamer and headpsace set in oz. and it uses a standard length action.

the 500 jeffery, 500asquare (a2) and 495 a2 are all rebated, a bunch. not a huge issue, but it is an issue for your gunsmith to sort out.

one of the best feeding rounds on the planet, the 45 ACP, has nil body taper..

shoulders, belts, and taper.. they are all easy enough to work around.

No offense to mr weiland, but doesn't he also feel all big bores are worthless?

Thanks for the reply Jeffe.

Best,
Marlin45

WeeWee Wieland as he's know around here has frankly lots to learn about big bores. To be honest ANYTHING can be made to feed if one pays just a bit of attention to the physics. The problem is many great gunsmiths really dont have a clue and Dremel tool their way into YOUR problems. Just about anything can be fixed with a good TIG welder and time. Personally, I've have had great luck with the 500a2 and 505 Gibbs, and even made the 585 Nyati work. Worst feeder was a 500 AHR ( pre-Wayne), but I got that too eventually .-Rob

500 Mbogo: What Jeffe said.
Use a CZ 550 Magnum, or a BRNO ZKK 602.
You can start with the common CZ .458 WinMag, just make sure the box in it is marked for .458, and is the smoothed-sided one, not the ribbed one that is marked ".375."
The .458 box is roomier, better for the 500 Mbogo.
Just open up the bolt face on the .458WinMag.
Polish the rails and ramp.

You will find CZ .416 Rigby rifles that have the .375 H&H mag box, and hold only three down.
Switching the box to .458 will make it hold 4 down and feed better, in my experience.

My latest 500 Mbogo was made from a .458 WinMag CZ 550 Magnum parts gun that I bought for $350.
CZ USA in Kansas dumped a couple of those at a local dealer, I bought both of those.
It had one of those bent barrels I think.
Simply rebarreled to 500 Mbogo, it fed well as it was, even rough as a cob from the CZ factory.
It fed well with all pointy and round nose bullets, and FN solids of less than 70% meplat.

With >70% meplat FN solids, it feeds well from the right side of the box, but balks from the left side.

It is going back to Rusty McGee to get slicked up on the left side.
Rusty has already installed a LaPour safety, and a Timney trigger is next, with the finish on the feed job.

It holds 3 down in 500 Mbogo with room to spare using that "458" stamped sheetmetal box.
It will be a 4-shooter.
That box is getting re-inforced at the front also.
It is a work in progress.
I am very happy with it.

I would have to agree with the above statements. I have a Ruger RSM in 500 Jeffery and I had Jim Dubell set it up for Woodleigh 570grn .510 projectiles exculsively such that it feeds these slick as butter but can hang up on flat nosed bullets such as the Hornady. ALL of the 500's are specialty rounds and maybe you should decide what you really want it for first. You can make a relatively inexpensive .500 boomer or go for a semi-custom look like the RSM my only advice is try and shoot a .50 first if your really serious about making a hunting rifle having owned an fired a RSM in 375, 416, 458 and 500 I can tell you that extra 1000 ft-lbs really makes a big difference in tolerability and you may want to build a more shootable gun ie heavier in the long run my 500 barely tips the scales at 9.5lbs and kicks like a pissed off mule with full house 2300fps + 570grn loads.



Cheers Brad

Agree Brad, my 500 Jeffery weighs in at 11 lbs empty without sling and I shoot the same 570g at 2300 fps. Offhand it's fine, from the bench with a lead sled with 35 lbs of weight on it, it lifts the sled several inches off of the bench and moves it back 3 inches with each shot. I won't shoot it off the bench anymore without a lead sled. Beautiful rifle by the way.

Thank you for the replies. All have added some food for thought.

Both rifles would look great in my safe i reckon!!..... so if your feeling generous......

Thanks again for your time.
Marcus.

Here's a picture of my 500 Jeffery, just a CZ 550 with AHR's CZ #1 upgrade.

I agree with Robgunbuilder, any of them will feed if they are properly set up..Most of mine have been the 500 Jefferys and the 505 Gibs calibers on Remington Mod. 30 or Enfield actions as the action is large to start with but not bulky..I suspect the Ruger and the CZ will work just fine but I'm betting they also need a good deal of work. I have seen these calibers converter to feed off a stacked magazine, but I never liked them much..I would prefer to use either a drop box or a milled out 3/8 or thicker floorplate that allows an extra round or two. The thick floor plate looks clean and I like it really well. I am making one for my 404 Jefferys Rem 30-S so it holds 4 for sure and hopefully 5 down.

quote:

Originally posted by jeffeosso:
Frankly, the 500 Mbogo and the 500 AccRel are likely the 2 best feeding .510 out there. they were designed to do that.

there's a 500AccRel reamer and headpsace set in oz. and it uses a standard length action.

the 500 jeffery, 500asquare (a2) and 495 a2 are all rebated, a bunch. not a huge issue, but it is an issue for your gunsmith to sort out.

one of the best feeding rounds on the planet, the 45 ACP, has nil body taper..

shoulders, belts, and taper.. they are all easy enough to work around.

No offense to mr weiland, but doesn't he also feel all big bores are worthless?

Jeff is right. If I was building a new 500 (i"m not) I would go with Jeff's 500ACCRel. Wonderful case design and much less recoil. Don't get me wrong. I have a 500 Jeffery and love it but Jeff's cartridge is better.

500 Mbogo on a magnum length action, 500 AR on standard length, clear choices.

quote:

Originally posted by Atkinson:
I agree with Robgunbuilder, any of them will feed if they are properly set up..Most of mine have been the 500 Jefferys and the 505 Gibs calibers on Remington Mod. 30 or Enfield actions as the action is large to start with but not bulky..I suspect the Ruger and the CZ will work just fine but I'm betting they also need a good deal of work. I have seen these calibers converter to feed off a stacked magazine, but I never liked them much..I would prefer to use either a drop box or a milled out 3/8 or thicker floorplate that allows an extra round or two. The thick floor plate looks clean and I like it really well. I am making one for my 404 Jefferys Rem 30-S so it holds 4 for sure and hopefully 5 down.

You're absolutely right Ray. My 500 Jeffery was worked on by 3 good gunsmiths before it functioned perfectly, which it does now. It always shot sub MOA, but that doesn't help if it jams.

I have an Empire chambered in 505 Empire. That's a necked-up 460 Wby, so supplies are relatively cheap. I have 2 loads for it...a 600gr Barnes solid at 2,150 fps (Ele) and a 525gr at 2,400 (Buff). I took the rifle and loads to Griffin & Howe when I bought it, and had them slick up the feeding specifically for these 2 loads. Worth the investment.

I also have a 505 Empire and really like the rifle. As Biebs posted, reloading components are cheap in comparison to other big bores in this class. Feeding must be a commmon problem with Empire Rifles because I had to work on my rifle too. I also had to have the floorplate spring replaced because it would fly open everytime the rifle was fired.

Dawson,
As you state, every DG caliber rifle should have an extra strong floorplate spring, a simple addition, but its surprising how many gunbuilders don't do that! but most custom gun builders don't actually use the big bores, they too busy making guns to hunt I suppose..

Everyone should require a heavy floorplate spring with ordering the rifle. It is the number one problem in Africas gun failures. That ping as all your loads fall out on the ground and Mbogo is coming your way must be a sick feeling.