im not really sure about the 470 NE since I don't own one but I sure wish my 450-400 3" had longer barrels. my rifle has 23.5" barrels which in my opinion are too short for the 450-400 3". a nice 26" or even a 28" barrel would really bring out the cartridges full potential. there is also the added benefit of having a longer sight radius which would make for better accuracy. having paid very "little" for my rifle, im in no position to be choosey on barrel length though.
rough performance estimates for the 450-400 3":
24" barrel = 2050 FPS with 3700 FT/LB of energy
26" barrel = 2100 FPS with 3900 FT/LB of energy
28" barrel = 2150 FPS with 4100 FT/LB of energy
loads can be pushed in a 24" barrel to match the 28" barrel but you start running fairly high pressures for a double rifle. from my reading the "correct" barrel length for the 450-400 3" is 28" which is why most people quote the speed at 2150. this may or may not be true for the 470 NE so this data may be irrelevant for you but I figured it would provide some food for thought.
-matt
Hi Matt,
I strongly suspect that, back in the golden years of the Nitro Express rifles and cartridges, Kynoch, Eley Bros, and others, were fluffing a bit on their claimed velocities.
I had an Army & Navy SxS, in .450 No2 Nitro (that cartridge was not derived from any existing black powder one).
The original claimed velocity with 480 gr bullets, soft and solid was 2175 fps.
Firing mine through a chronograph at that velocity showed no pressure signs at all but likewise would not regulate with Woodleighs or Hornadys at anywhere near that speed (only 480 gr bullets I had access to at the time, Hawks were back-ordered).
My old smasher settled right down at 2050 fps (4 shots into 2.5 inches @ 50 yds over wide/shallow "V" rear and over-size white front bead.)
It liked the Hndy DGX an d DGS a b it more than it did the Woodleighs, much to my surprise, so I shot a buffalo with them and was delighted with the result.
He is shown as my avatar.
"Velocity is usually fine but accuracy is usually final."
Cheerio,
Velo Dog.