Not really a Kirby mag, but look what happened to my head after shooting my 375 RUM Kirby built (plus the 338 RUM and 300 RUM he made). All the guns sport 30" Lilja tubes and the excellent Holland QD brakes, custom stocks, trigger jobs and one of my favorites, he drills out the scope bases for #8-40 - my all time favorite, what he does to the triggers (going from 5-7 lbs to 1.5 lbs)
After shooting my 375 RUM I picked up my factory a-bolt stainless stocker in 270 WSM with 135gr MK & 62.5g of IMR-4350.
The little 270 kicks so much harder than my Kirby guns it dinged my head. It's also very difficult to shoot the factory trigger after getting spoiled by kirby's triggers.
I still find it amazing the big 375 RUM kicks so much less than the 270 WSM.
Due to a BUG IN THIS FOURM SOFTWARE I CAN'T EMBED the Image, so you can click to see the damage. Kirby Mag Post head trauma