Originally Posted by jmden
JC, Would you mind posting pics of the 338 UltraMaxx with 300SMK loaded? Perhaps next to a 300RUM or 7mmRUM case if you have it?
I'm assuming you neck up 300RUM cases and then fireform, is that correct? Is this Kirby's creation?
What is your OAL with the 300SMK boatail/body junction at the neck/shoulder junction?
What is your ff load? A guess at your max load?
Sorry for all the questions, I'm contemplating a 338 'something' at the moment and although I now recall hearing something about this chambering sometime ago, I did not recall all the details.
Yes Iím necking up 300 brass to .338 but I think it would be better to neck down 375 RUM brass that way I wouldnít have to seat the bullet hard into the lands.
Well itís no secrete that Kirby designed the .270 Allen and since Kirby always gets the max ability out of any of his cases, thatís why I came up with the name UltraMaxx. Kirby and I talked about several .338s and I decided I would just like to use his 270 dimensions with a .338 neck.
OAL length is still up in the air as this thing has only been shot 22 times, and that includes the barrel brake in with gun juice. So I have a lot of load development ahead of me. Right now my fire-forming load is 93gr of Reloader-25
Itís shooting really well at 500 yards at about Ĺ MOA thatís why I let my dad use it.
The reason for going with a rifle built for the RUM case instead of the Lapua case is availability. I already have the .338 AM and cases tried up on them for a while. Than I have my 270 AM, know I hear my 169.5 and 195 wildcat bullets for it might be no more. So I figured the .338 UltraMaxx would best for me. I can get RUM brass and the 300 SMK anytime I need it.