8mm XCB

[338RemUltraMag]

Ok lets discuss the 8mm XCB, I am going to start with the 8mm-06 as a start, I would love some geniuses input here.

Joshua

[felix]

Actually, I like the idea myself. My preference would be the stock 8 Mauser case but with the neck length of the 30-30 for deep seating purposes. Why, because my barrel would have zero freebore with 3 degree total throat, and twist commensurate with the primary boolit shot. My primary boolit would be the RCBS 180, so my twist would be 16 with 3 to 7 lands, each 0.005 in height with a rounded junction to the groove at normal angle. ... felix

I don't know what you are really asking because your case selection is already designed very well. ... felix

[Love Life]

I just don't see what the 8mm XCB gives you that the 8X57 in a purpose built rifle wouldn't.

[btroj]

It gives a longer neck and a different throat. A customer reamer could do the same on an otherwise stock 8 x 57 case by moving the shoulder a touch.

Biggest trouble with a custom reamer is getting a sizer that works.

[tomme boy]

Don't you use the same reamer on a blank die set that you use to do the chamber. I thought that was how you did it.

[338RemUltraMag]

I would be happy with a 8mm-06 standard made, if it were to be changed I would like the shoulder set back .075 to make a longer neck. But that is if we HAVE to play with the cartridge.

[felix]

Bonanza-Forster loves that kind of work. Send them the reamers. ... felix

[338RemUltraMag]

Ok, I just looked in my loading manual, the 8mm-06 will push a 220 gr bullet to 2500 fps. That is exactly the performance I am looking for.

Do we need to change the design or should we just call this good? I know an easy way to make a *slightly* longer neck is to use 270 brass.

[felix]

You got the case size you want in the standard 06. Why not use it without "qualming" about it? Remember, a lead boolit will shoot faster than a condom, suggesting the 06 size is slightly large. Hence, the stock German case size, or the XCB size. Do your own extrapolations. ... felix

[338RemUltraMag]

You got the case size you want in the standard 06. Why not use it without "qualming" about it? Remember, a lead boolit will shoot faster than a condom, suggesting the 06 size is slightly large. Hence, the stock German case size, or the XCB size. Do your own extrapolations. ... felix

I ask for the ideas of other people smarter than I because I do not know everything, ya know I dont see a need for smart **** remarks.

[btroj]

I don't think it was a smart **** comment, I think Felix was saying to think about it and the realities become rather obvious.

If an 8 mm 06 does 2500 with a 220 jacketed and lead would go faster then Felix is telling you it is too much case. Go with a 8 x 57 or the XCB case to reduce powder capacity.

8 x 57 eliminates all troubles in case forming, dies, etc. the XCB gives a better neck design and throat but requires some case forming. It would allow a tighter neck, use a neck turner, and get more preside bullet alignment.

So, what do you want and what are you willing to do?

[Love Life]

It would allow a tighter neck, use a neck turner, and get more preside bullet alignment.

Neck turning gets old. Just get a match chamber cut correctly and you will be fine unless you are competing in legit benchrest.

[cbrick]

I ask for the ideas of other people smarter than I because I do not know everything, ya know I dont see a need for smart **** remarks.

Hhmmm . . . Read through this post and thought I missed something. Went back and read it again so at least I now know that I did miss something, dunno what but I must have.

I just didn't see anything even close to a smart **** remark.

Rick

[btroj]

Neck turning gets old. Just get a match chamber cut correctly and you will be fine unless you are competing in legit benchrest.

Agreed. Just that some enjoy turning. Weird.

[338RemUltraMag]

I am sorry for being nippy, and I openly apologize to Felix, as fas as case forming I enjoy that kind of thing, so I will go with a 30 XCB necked up with no further changes. That will allow all the speed necessary and will be a proven design.

Now Tim, is the reamer a removable pilot or fixed reamer? If removable is it possible to use it to make the 8 XCB?

[Love Life]

Agreed. Just that some enjoy turning. Weird.

That is weird...unless you CBRick's awesome and amazing case prep contraption. I don't want to get off topic though.

I can see the benefits of the longer neck in the cartridge, and I hope it shoots really well.

[btroj]

I am sorry for being nippy, and I openly apologize to Felix, as fas as case forming I enjoy that kind of thing, so I will go with a 30 XCB necked up with no further changes. That will allow all the speed necessary and will be a proven design.

Now Tim, is the reamer a removable pilot or fixed reamer? If removable is it possible to use it to make the 8 XCB?

The 06 reamer used for the 30 XCB won't cut an 8 mm neck. Pilot size doesn't matter for neck size.

For 8 mm XCB you need an 8 mm 06 reamer.

[btroj]

That is weird...unless you CBRick's awesome and amazing case prep contraption. I don't want to get off topic though.

I can see the benefits of the longer neck in the cartridge, and I hope it shoots really well.

I forgot about that prep center. Now I'm drooling again.

[HARRYMPOPE]

Jesse Dresler in Oregon has done a short 8mm on a BR or 308 x 1.65 case ( can't remember the details) it was not any adbantage over a short 30 and was.abandoned.Roy Smith's 338 Manx on a 1.5"(or so) .473 head diameter case was a success and should be revived.

[tomme boy]

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.