Home Forums Hunting & Shooting Express Rifles and Big Bores Only Question for the .400 Whelen Crowd

Reference material:



BBMT provided measurements from samples of one bullet each of the two above.

400-gr/.411" ex-Nosler Partition: BOL = 1.485", seat depth with crimp at cannelure =0.725", COL with 2.490" brass = 3.250"

350-gr/.410" Swift A-Frame: BOL = 1.285", seat depth with crimp at cannelure = 0.575", COL with 2.490" brass = 3.200"



A 400-gr/.410" Swift A-Frame would be even more sure to obturate to .411" groove, since sectional density drives expansion for any given velocity.
It is much better to shoot a jacketed or monometal bullet that is .001" to .002" smaller than groove diameter
than to shoot one that is 0.001" or more over groove diameter.
The 0.423" North Fork bullets worked well in my 0.425"-grooved McGowen barrels, sub-MOA capable.
A tighter fit might have increased velocity AND pressure with monometal copper/jacketed bullets.
Not like the smokeless loads with lead bullets that are not at their best until 0.002" greater than groove diameter,
for any reasonable rifle bullet diameter, of course, like .400-cal and up.
That is where reasonable starts.