So, now that we see those beautiful 550 cal barrels being turned out, I can't help but think of necking up a Gibbs and sticking it into the new CZ 505 if it actually happens this next year.
From what I hear there's n shortage of powder room using the Weatherby case, but if the CZ can really handle the nominal 3.85" Gibbs round, and seeing as how it's some .045" thicker at the base, you could get about 30% MORE room under the same bullet.
Nuts? Perhaps. But it's just begging to be done! I saw Jurrasic Park and, frankly, it got me a little worried.

Case capacity below a bullet seated in .4 in in the 505
is about 160 gr water and in the 550 about 140 gr.For the
extra work making reamers, chambers, dies, etc, not enough
gain to do it, I feel. With maximum loads of the right ball
powder, and with that straight case effiency, you can get 600 gr bullet over 2600 fps.
Between 9-10000 ft lbs..Ed

Hmm. I don't have sized cases to measure, but RCBS's software says about 170 vs 125g of water below a bullet seated .4" in. If true, that's quite a difference.

The 550 case is 3 inches long and nearly straight, and

holds more than that.About 140 on case I measured.My Donnelly book shows 505 as having total cap of about 180 gr water, and a bullet seated .4 subtacts about 20 gr.Of course straightening sides will add 10 to

15 gr, but you have to use slower powders,

so the energy gains doesn't follow volume gains equally.

If you were going to the work of making a bottlenecked

550, you would do better to use the Nyati case.Just design a case from Nyati basic brass, about 3.2 inches long(the

basic cases are long enough to do that), and you would have about 20 gr more than 505 case.My 550HE belted straight case is made from Nyati and it holds 200 gr below bullet.It is 3.45 inches long.But then if you were going for that much more power, go to the 600 OK, another simple straight case.It will fit in that CZ..Ed.