8mm XCB

[Newtire]

I think a 8mm-08 case with a 3006 length neck would be perfect for this. It should be way more efficient than a 8-06 Plus it would work on a short action. You could use 7x57, 8x57 brass if you have it. Or 3006 if you really want to do a lot of case work.

Not really that much work tomme boy. If I'm hearing this right, a .30-06 case with the shoulder shoved back to make a longer neck. I've done this before to form a whole batch of 8mm brass. I turned off the excess in my case trimmer using my Makita to run it and then knocked off the huge burr by running it up into my sizing die just enough to break off the burr and then finishing it off with the chamfering tool. Works real slick. You could drive over to Lanark to Forsters from Clinton and pick up your dies in person even.

[runfiverun]

it's more involved than a simple re-form to 8 mauser.
the neck/shoulder/throat relationship is much, much different.

you turn the necks simply to get everything exact with the minimum of trouble keeping everything in that relationship as perfect as possible.
an inside neck reamer for the cases would definitely be a quick way of getting what you wanted if you could control the wobble of the cutting motor/tool.
but a concentric turn is definitely the way to go.
it also allows you to manipulate the centerline of the barrel/boolit relationship with the brass thickness.

[geargnasher]

+1 Lamar.

There is definitely a call for a ".30 Mauser" or the slightly less tapered body of the .30 XCB because no other cartridge in that niche exists, but in 8mm or even .35 caliber I can see no advantage that a similarly-sized wildcat case might have over the already proven 8X57 JM Mauser or (if needed) the '06 family (8mm, .338, .35 Whelen, etc).

What we get into is efficiency with preferred powder burn rate and preferred boolit weight per caliber and expansion ratio. At 24-2600 fps in a .30-'06 there is always about 5-10 grains of extra room in the case which requires buffer or filler to optimize. The .308 Winchester is too small and the neck shorter than we'd like to gain similar velocities with cast-friendly burn-rate powders. The .30 XCB is just perfect for 150-180-grain boolits at 24-2700 fps at 100% loading density and upper-40K PSI peak pressure. The 8mm Mauser is close to perfect in all respects for maximizing typical 8mm boolit weight performance. Fixating on having a longer neck than the 8mm Mauser is looking for a solution to a problem that really doesn't exist in my opinion.

As for the 8mm '06, it may not be ideal, but a removable-pilot '06 reamer could be fitted with an 8mm pilot and the neck cut with a neck/throat reamer.

Gear

[Newtire]

it's more involved than a simple re-form to 8 mauser.
the neck/shoulder/throat relationship is much, much different.

you turn the necks simply to get everything exact with the minimum of trouble keeping everything in that relationship as perfect as possible.
an inside neck reamer for the cases would definitely be a quick way of getting what you wanted if you could control the wobble of the cutting motor/tool.
but a concentric turn is definitely the way to go.
it also allows you to manipulate the centerline of the barrel/boolit relationship with the brass thickness.

I thought you were wanting a longer neck on an 8mm case. You would have to cut the chamber for a longer throat of course the way I see it. Neck turning is a whole nother area to discuss.

[runfiverun]

the longer neck would be a benefit.
if the sides of the neck were/are cut parallel in the chamber.
it helps with the whole centerline thing again.
the 8m [32] XCB if designed similarly to the 30 XCB would gain the same benefits of the case volume over an 0-6 sized case.
it would basically duplicate the 8 mauser's case capacity but would change the neck/shoulder angle slightly and give a slightly [to much] longer neck [if the reamer was made that way]
a fairly parallel case wall [like Ackley cases have] and neck is a huge help when shooting lead.
you'd have to of course design the case with the action length in mind, as you could stretch the neck out another 4mm if you wanted to use the larger X61 case.

the waay longer neck is something that was discussed in the original planning stages of this XCB thing.
one of the first rounds discussed had a case volume of the 300 savage with a 30-30 length neck giving the round a 2.015 case length.