300 Lapua wildcat ID

A friend of mine shown me this round.I tough it was a fireformed 300 Lapua,but it has a slighty longer neck ( and a different shoulder angle,I think) compared with the commercial 300 Lapua case.
Can you identify this 300 Lapua wildcat variation?Does it have a particoular name?
Left:commercial 300 Lapua case,neck lenght:8,69 mm
Right:the unnamed wildcat,neck lenght:9,39 mm

case lenght and other diameters are the same,so the shoulder angle should be sharper in the wildcat round


There are several 300 RUM Improved cartridges used in long range competition. There are very small differences between them, primarily shoulder angle, shoulder diameter, and neck length. The same cartridges can be found made from 404 Jeffery brass. They have various names.

Yours appears to have a 30 degree shoulder. Measure the shoulder diameter to see if it is the same as the RUM. If it is, then it is not really an improved cartridge but simply a 300 RUM, 30 Degree.

Unless you can find the inventor and ask him what he calls it, you can call it anything you want, I suppose.


it is not a 300 RUM,but a 30" caliber wildcat based on the 338 Lapua magnum case.There are many differences between this wildcat and the 300 RUM,rim,body and shoulder diam,case,body and neck lenght

from left:
300 Lapua magnum,commercial case
30 - 338 wildcat
300 RUM


I’m sorry. I mis-read your original post. I thought it said 300 RUM.

Regardless, most of my comments still apply. There are many competition wildcats made from the LAPUA Magnum brass, both 300 and 338. I have one that is virtually identical to yours that the shooter simply calls the 30/338 LAPUA.

All of the wide-bodied magnum cases have been wildcatted ad-naseum and there is not much that hasn’t been done, more than once. Since the Norma brass is so much cheaper than Lapua, most shooters use it. Most of the cartrtidges are 30 or 338 caliber, shooting the very long heavy match bullets.