I ordered a 338-06 from cooper and now I have been on loaddata.com getting some ideas for loads and I noticed that there is a lot of data, but there are 3 neck angles. They have the A-Square that is 17 degrees. The IA which is 40 degree's. Then there is a lot of data with a 34.25 degree neck. Where is the 34.25 coming from? I thought there was only 2 neck angles. Any info would be great.

I don't know the answer on that one but since yours is the A-Square I'd stick with that data. Those Cooper rifles sure are pretty, post some pictures when you get it. You are going to love the .338-06!

I'd try some RL 15 and 210 grain Nosler Partitions or 200 grain Accubonds.

There were several 338-06 versions on the table before A-Square made it commercial. The std is a 17 just like a 30-06. AI versions are 40 Huntington with RCBS did most of the same work as Ackley but used a 30-32 deg. Gibbs made a 338 with a 35 there is a 338clipper which is a 338 in a 280 case. I make a 340PDK a shoulder forward280 case Gibbs style with 40. The list goes on and on.

Like I said the std is 17 (17.5) like the 06.

I used to swap between 180s and 210Part depending on what I was hunting. Now I use the 200 accubond for everythnhg from small whitetail to elk. Powders in the RL15, 414, 4064 range work for me

I think the 338-06 Scovill is the other model with the 24 or 34 degree shoulder. I seen load data for it in the Barnes reload.

Me I went with the Ackley Improved on my 338-06 with 225gr Accubonds and TTSX's. My reloading dies are Reddings-thats what my gunsmith brought in for me when I had the rifle built.

OK from memory again as I understand the 338-06 scovill was really called the 338 Scovill. Which started life as the 375 Scovill or 375 Hawk Scovill then necked down to 338. The original 375 Scovill was was built on 9.3x62 brass the 375Hawk and now the 338Hawk simply substituted the more easy to get 06 brass. By the way the Scovill used the 17 deg shoulder of the 06 which if you look at drawings they often show the total combined angle of both sides as being 34.56deg. The 340 Howell uses a long 06 case and 25deg.

After I got through typing I found where I had stuck the comments below. It was stolen from the Alaska forum fo I didn't verify everything.

Yeah, all the above. Ballistics are all so close and that shouldn't be the criteria for selection. I don't know how much you have researched these but there are differences all involving the shoulder diameter and angle and the case neck length.
The original caliber was 375 and was developed by Bob Fulton, designer of Hawk bullets and Fred Zeglin of Z-Hat gunsmithing. It originally used the brass, or at least the base dimensions of the 9.3x62 case which is a about .006" larger in diameter than the '06 case. But the shoulder is farther forward than the '06 and larger in diameter. Dave Scovill was sent a sample rifle and decided to change the back half of the chamber dims. to '06 with front of the chamber dims of the 9.3. So on the Scovill version, or as he calls it, the Hawk/Scovill, 30-06 cases are necked up to .424" then necked down to .375 to form a false shoulder for head spacing. Of course with the 338, we can now use 35 Whelen brass and just neck down to 338 and in a correctly made chamber, will head space correctly. If you order a reamer for this make sure and ask for the Scovill, the Hawk version is larger at the base and will bulge the 30-06 brass a little when fired. Also the throat dimensions must be specified for you prefered bullet.
The advantage of the Hawk/Scovill is that it retains the original shoulder angle of 17 degrees, 30', of the 30-06 (also the 9.3x62) and will feed a little more smoothly than the Ackley version. The neck is shorter and on the 338 caliber it is about .320", which is where most of the powder capacity gain is from the standard 30-06 case. The shoulder diameter is also increased by about .015" to around .455". I'm going from memory here so don't quote me. Velocity gain over the standard 338-06 is about 50-100 fps but I think there are some other advantages. The 30-06 has always had too much neck, more than needed to hold any bullet securely. It also has more body taper than is needed to feed smoothly. Why not use that space for some ballistic advantage. The Ackley has a forty degree shoulder and bare minimum body taper. This was done to get maximum powder capacity in the case yet allow the firing of standard ammo to form brass. Standard factory 30-06(or 338-06) can be safely headspaced in Ackley chambers, if the chamber was made correctly. You must form the brass to fit then fire form in all the other versions. More work but part of the fun. I think the Barnes manual includes the Scovills because of Dave's ties with Eric Peterson of Barnes who does the load development for them. The RCBS version also moves the shoulder forward but has a 28 degree shoulder. My version was based on the 9.3x62 case also. I abandoned that project because at that time I could not find brass for that one. I then paid $40.00 for 600 rounds of Norma 9.3x64 brass and started to turn that into various calibers. That project has been ongoing for about 12 years now. That is really a great case for a 30-06 length action and will meet 300 Weatherby velocities with a 30 caliber beltless cartridge. Of course it can be 338 or 358 or 375 or 416 or 423 or... well you get the idea. I could use an associate with that project.
It is always fun to build something very unique and to hunt and take game with a cartridge you made by hand, almost like napping your own arrow heads. I do like the Scovill cartridges. There are benefits and with the right equipment they are easy and quick to make from readily available brass. I would stay with the 338 or the 375. As always, I'm long winded, but I hope this helps a bit. Good luck and good shootin'.

Thanks that really helped.

If any one wants them, here is 118 pages of CIP case and chamber drawings of rimless shells I don't think that the 338-06 is there.
http://www.intermin.fi/intermi...DE/$file/TABIcal.pdf