Originally Posted by chuckhammer
Kirby's page says you can expect 3400 fps from a 180 in his 7AM. Gotta be a super-hot load.
The 7mm in our short, medium and long Lapua based Fatso range that uses the 2.7" full length Lapua case is called the 7mm FX (Fatso Xtreme). It pushes the 180gn Berger at 3400fps out of a 28" barrel at a comfortable 65,000psi. A 30" barrel will give you 3460fps at the same comfortable 65,000psi pressure. Kirby's 7mm AM is quite similar, so similar velocity for pressure.
The medium 2.5" long version using the 300 NM is called the 7mm Fatmax, and pushes the 180gn at 3300 out of a 28" barrel for 65,000psi. This is measured pressure with an Oehler 43 ballistic laboratory, not just going off pressure signs.
With a sensible throat length and powder choice these big 7mm's will surprise you just how long their barrel life is!