The reamer is an off-the-rack item from Clymer, .505 Gibbs necked up to .510" is called .51 Gibbs.

I'm glad you all are thinking about this, because I don't have Quickload, and looking over your shoulders is great fun.

A case full of IMR 5010 (140-145gr or so) goes 2100 fps with a 700 gr bullet. I gave up on WC 872 because it was going really slow. WC 872 is a ball powder and packs pretty tight, so going up one grain at a time was going to take a while. 5010 is the usual IMR sticks, only bigger, so I could get the case full faster.

I was working my way up with WC852 (slow), and I had gotten up to 2365 with a 700gr bullet out of a 32" barrel before I stopped to restock. At my present rate I might finish restocking in late February.

Hangfires are common with the lighter loads if you don't do something to use up the extra space in the case. Typically the delay is in the neighborhood of .1-.2 sec. Click-Boom.....

I sent an assembled case to CH4D, and he modified a set of .505 Gibbs dies to do the job. I have had no problems with them so far. I have only loaded/fired 80 rounds or so.

Mine is built on an Enfield action in need of considerable work. I'd like to feed shorter bullets out of the magazine, but a lot needs to be done to make that possible. Someday I want to try some of the muzzleloader .510" sabots with the 300 gr .45 cal pistol bullets. That should be great fun on targets that will expand the bullets.

From Quickload
195gn H2O 4.8" COL
30" bbl 647gn Speer
162gns H870 2295fps 37,800psi 100% load density
162gns H1000 2506fps 54,000psi 101% load density
162gns H4831SC 2610fps 63,000psi 101% load density

165gns Ramshot Magnum 2540fps 54,000psi 100% load density
154gns RL25 2490fps 50,000psi 100% load density
157gns RL22 2600fps 60,000psi 100% load density

750 Hornady A-max
141gns RL22 2340fps 56,300psi 100% load density
149gns Ramshot Magnum 2310fps 50,000psi 100% load density
144gns H1000 2240fps 48,400psi 100% load density
144gns H4831SC 2340fps 57,300psi 100% load density

From Quickload

Thanks Lar45. Very cool.
So, we have a 750g A-MAX doing about 2350 fps, without pushing the pressure.
That means about 1630 fps at 1k, as opposed to the BMG's 1950. Another 245ms to target (1534ms).
A 300g .338" SMK going 2665 will have the same terminal velocity, and take 1440 ms to get there with about 14% less drift, which speed the Lap will do with 30". So given choice of caliber, the .338" might make the same hole in paper, better, with less recoil.
But then, look at the 50 Peacekeeper, made off the Weatherby case, and its 750 going 2200. That case has about 22% less capacity. Wonder what SSk loads that one to, and how this case would fare at same....
It would need to do the 2500 I was thinking of, in my eyes, to be a contender to the BMG. From the above figures, looks like we're talking about something like 60k psi.
Now, take the new 700 NE case(if you can find it!), give it a COL of say 5.04" (same case-length:COL measurement as BMG) and you have virtually the same powder capacity as the old BMG.
The M1999 won't handle that .780" casehead, but hmmm.... What else.

Interesting note, by using more or less the same taper and necking to .510" with a .450" neck, 35 deg shoulder, the T-Rex, 577 Nitro, 600 nitro and Gibbs cases all come out to about 200 water capacity, with different lengths of course. The 600 Nitro wins with a .70" base dia.
Funny how close they all are. Curious.

But of course. what this all means is that we have to take the 600 NE, turn a rim onto it, neck to .510" and seat out to 3.98" for a 50-cal long-range repeater PH1999 with 205g water capacity.
Who makes a good 650g VLD? Load the case full of RL22 and see what happens.

Hi, new guy here...first post. I like the idea. With .50BMGs banned in CA, I have been thinking of alternatives. I like the idea of a .408 Weatherby. Take a .416 Wby. case and neck it down to .408, and use bullets for the Chey-Tac. Or, if Sierra would come out with a 500gr., .458 Matchking, that could be used in a .460 Wby. case, or the .505 case. Both would be long range thumpers that you could use standard dies & presses.