375 Remington Ultra Magnum necked up to 50 caliber (.510)

[Deleted member 46119]

jfseaman are you planning on running it as a single shot or as a repeater ? I guess it would depend on the bullet that you plan on using.

If sub-sonic, definitely repeater as none of those bullets are long enough to stop that.

Some of the bigger bullets that I should be able to get to 1750fps would be single load.

 

[sable tireur]

Good Morning,

I did some checking around and head scratching last night only to remember that there is a 2" version of the .510 Wells Express that I did several years ago. I have to run to the shop to get the file to see what the case capacity is before running any more numbers. On the surface, it appears to run in the 1700 fps. range with the 750 AMAX seated out to 3.850" magazine length.

I was sorting through some of the material I received at SHOT Show and remembered that APO was releasing a .408 Chey-Tac action and chassis. The chassis is set up to take the .408 C-T magazines at 4.515" length. If you keep the original case length for the .510 Wells Express, the 750 AMAX will drop right in and run in the 1950 - 2000 fps range.

The SABER®-FORSST® Modular Rifle Chassis System | Ashbury Precision Ordnance, Mfg.

The next step would be to neck the .408 C-T case up to .510 and run it straight out in the APO chassis. This will get you to the 2,000 - 2150 fps range easily.

Consideration has to be given to the cost of projects such as this. Going big goes expensive.

Other than that, enjoy the process!

Regards.

 

[375rifleman]

What is the difference ballistic performance, action compatibility, and price wise between the 500 A-Square and the 510 Wells Express ? I don't want to step on anyone's toes here but aren't they both variations of a 460 Weatherby necked up to .50 caliber (.510) wildcat rifle cartridge ?

 

[sable tireur]

375rifleman,

There aren't any toes to step on. Col. Alphin and Fred Wells have both been deceased for many years.

There is very little difference between the two cartridges, nothing significant anyway. Both are derived from the .460 Weatherby for the intent of shooting any of the Big Five African dangerous game animals. The difference that I was made aware of is that Fred created his version in about 1969 but never did anything to protect the concept since he didn't really believe in that sort of thing. He built custom rifles for folks headed to Africa to hunt dangerous game.

Col. Alphin believed that everything he did warranted some form of trademark or protection from others using his ideas. In the situation of the .500 A-Square in 1976, Col. Alphin retained all of the information about the design and only released ammunition through his company, making the cartridge 'proprietary'. Nice man but a tiny bit egotistical...

Price difference? The .510 Wells express is simply a reamer and brass. Dave Kiff has the print and will make a reamer for you. If you're intent on using the 750 AMAX, then you need to work out the throat for the reamer or have a secondary throating reamer.

The .500 A-Square has been out of production since 2011. I'm sure you can find dies somewhere then get one of the reamer makers to make a reamer for you if the family has released it into the public domain.

Regards.

 

[375rifleman]

Hello everyone,
I was wondering if somebody could take some measurements for me ? I was wondering what the real C.O.A.L. measurement would be of a 500 A-Squre/510 Wells Express/or a 460 Weatherby Magnum necked up to .510 with a 750gr Hornady A-Max. It would be greatly appreciated.

Regards,
375rifleman

 

[hubel458]

I made some for couple guys years ago using the .500" bullets,

by doing a belt on 375 RUM cases, expanding mouth.

The cases measured .500" at base, that became belt dia.

Base ahead of belt was .530, straight side to mouth .520. Cases worked great

for them shooting 500gr and similar..

Ed

 

[widlin1]

I just stumble onto this thread with a search for Accurate Mag Chassis and thought I would add to it with some experience I had necking up and shortening .338 Lapua brass. Using multiple expanders and several annealing steps I was able to make brass and fire form in a lathe turned chamber with a reamer cut throat. I trimmed the brass to 2.540 to head spaced on the cartridge mouth, fire formed with a M33 ball projectile and 82 grains of BL-C(2) to make a small shoulder. Fire forming shortened the case to 2.525 or slightly longer. With 89 grains of the same powder I got up to 1900 fps with no signs of excessive pressure. With MK 211 bullets OAL was designed to be 4.175 to fit the max length of the PSR magazine. With Barnes TSX OAL was 3.85 inch.

Quick load indicated higher velocity with CFE 223, but I didn't have any at the time and have since put the Rigby barrel back on the rifle. Below are a few pictures I took along the way. Quick load also predicted 2300 fps doing the same neck up and trim to 408 Chetac brass and using a 27 inch barrel. That load would come very close to the trajectory of M118LR and cause detonation of the MK211 out to about 1400 meters.

Jeff

 

[Deleted member 46119]

Nice Turret lathe. Some people get get all the cool toys.

 

[biff's reloading]

.510 won't work. .500 barely works in the mdm. I built my rum in .475 so I have positive shoulder headspacing. I cast 530gr checked hard lead for it and load 500gr tsx and a few other 470ne bullets. if you want long range big bore on a .534 bolt, try .416 or .458 rum with cutting edge solids

 

[375rifleman]

A 338 Lapua X .510 (510 Whisper) pushing a 750gr A-Max to 1600fps-1900fps out of a 16"-18" barrel would be ideal in a shorter compact repeating bolt action. I can't decide if I should start with a Remington 700, a Savage 110, CZ-550 or another action.

375 Rifleman