Now for those who really want big bore bottlenecked cases,
I designed a bunch from a case that holds about 600 gr
ball powder.Work for 12Ga down to 550.Have to use charcoal
for powder. Will post pictures of a couple tomorrow.Their most redemming feature is that gunners think they are really something with the big shoulders.and I understand that as that is what shooters have been told by most writers and companies.Ed

So, I mentioned it on the wildcat forums, but the thought occured to me, with CZ coming out with a 505, and the new 550 caliber barrels we have available....
Anyone going to see what that case will do at 3.85" COL or whatever it is?

I thought about it but still not sure about bullets for the 550 yet.

Karl.

A lot of places are starting to mke bullets for 550.
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.And for a comparison the same best powder in 550 in a max load in the 505 case 550 would be too high of pressures, so you have to go to slower powder.Thus 15% gain in powder capacity doesn't give 15%
velocity increase,which would increase energy 30%, but only about a 15% energy increase..Ed

Hey, Ed. How long is that 550 case? I was assuming the same length as 460 WB, but maybe the baisc case is longer. Also, rather thanseating them the same depth, why not figure on max COL? -Assuming seating depth is within minimum. Th Gibbs case can lose ALOT of that taper. Maybe that's where our figures differ.

Bwana- The 550 case is 3 in.And yes and the Gibbs could be straightened out on the sides, but then you have to go

to slower powder for hairy loads, so your still not going to get 30% more energy.If you figured on the basis of the

COL the straight 550 Mag would gain more as the bullet could be seated out more..I am not enthusiastic about

getting in the middle of the

fat case/big shoulder versus straight case arguments, but here goes.

Check this page below.Anthony Williams cartridge site.The case on the right, 27mm Nato round(27x145B) and case third from right our 25mm Bushmaster round(25x137).Both have same powder capacity.

I have both and checked. Both built and loaded to same high pressures.Our case gets a 2800 gr bullet out at 3600, the Nato case gets a 4000 out at 3550.It is damn near straight,as pic shows.. Ed.