Gidday fellas, I am becoming totally involved with the 500m Fly Shoot. I need a caliber with either a 8mm bore or a .338 bore.
Does anyone have a decent ballistics program that can calculate for me what a 9.3 x66 Sako case will give me with a .338 dia 300gn Sierra projectile. Maybe a 250gn .338 as well.
My old eyes looking through the spotting scope require the largest sized hole possible
Thanks Malcolm

The OAL would be needed. Unless you can load to something longer than the standard 3.4" the 66 case will not gain you much over the 62 or even the 338-06.

I drew this up months ago. The first two should read 338-06 and 338-06AI and the green dashed would be a 66AI. The bullet base is a 225 in a 3.4" mag. If you go 250 or 300gr it will be much deeper. Unless you can move the bullet out that longer case is just filled with bullet. The only net gain is in the shoulder area.



Here is some Data listed on The AHR, Z-hat, Gibbs article and my own 340PDK actual.

340Howell 25" 250 gr @ 2600FPS
338 Hawke 26" 250@ 2500FPS
338 Gibbs 26" 250@ 2670FPS
338 Gibbs 26" 275@ 2560FPS

Actual Measure 340PDK nosler 250Pt at 3.37OAL in a 24" 2650FPS. I tried to load no higher than 63,000. There was no head expansion and I'm on the 6th loading on the brass. This velocity matches withing 35FPS of what Loadtech gives me at 63,000psi.

Using Loadtech to then forcast a 300 Sierra from the 340PDK I get 2450FPS @ 63,000

Based on my experience unless you can seat the bullet out you will gain maybe 1-2% more vleocity in the 66 case.

Wow Ramrod,---- thanks for the infomation. The OAL can be what ever as it will be in a single shot benchrest type rifle. I am not limited to a magazine at all.
I guess I may have to stick to a 250gn .338
Thanks again for your drawings
Malcolm

quote:

Wow Ramrod,---- thanks for the infomation. The OAL can be what ever as it will be in a single shot benchrest type rifle. I am not limited to a magazine at all.

Ok if that is the case. From the what's worth department taking the 66 case necking it down to 338. Then setting the chamber up so that a 250 grain bullet is only in to the base of the neck the OAL is right at 3.7. In a 26" barrel Loadtech calls it around 2725-30FPS. If you set the bullet out to 3.8 it would add about 25FPS. That would leave you with about .2" holding the bullet. A 28" barrel would add the same 25-30FPS.

Ramrod, again thanks heaps for the updated info.
2700 fps would do just nicely.
thanks