Nosler Guide 4 gives the following for the 280 - 160 gr. bullet - 2942 fps with 58.5 grs of 7828 and 175 bullet - 2800 fps with 57 grs of 7828. For the 280AI - 160 gr bullet - 2975 with 58 grs. of R-22 and with the 175 bullet - 2825 fps with 57.5 grs of 7828. These are the highest velocities listed for the two bullets - the 280 had a 26 in. barel and the 280AI has a 24 in. barrel. Is Nosler being conservative with the 280AI? What velocities can I realistically expect from a 280AI with a 26 in barrel with these two bullets?

I think you have to keep a few things in mind when you compare specs in a manual like this. First, note the barrel length differances, second, some rifles are simply "faster" then others. As to whether Nosler is being conservative, in todays litigous climate, I would assume so. Now having said that, if you follow some of the other threads in here regarding pressure and reading same, I think that you'll find starting with a manual's info is a pretty good choice. In a 7mm Gibbs I load for, I can better those fps figures by about 100 fps with all bullet weights, but again, every rifle is differant. I hope this helps a little. - Dan

All else being equal, you can probably expect a 100 to 150 fps increase over the standard 280.

A good rule of thumb.....What percentage increase in case capacity over the standard non improved round, versus the improved round?? Lets say 10% more capacity. And you have been getting 3000 fps with XYZ bullets.
Take HALF of the capacity increase, or 5% and thats generally how much more velocity you will gain. Five percent of 3000 fps would be 150 fps.
Not an amazingly scientific formula but its pretty darned close 90% of the time.

I agree on the 100 to 150 fps increse over a standard .280 Rem with all factors being equal. Same barrel length, cases, bullets, etc. BTW....I just sent out a 26" Rem 700 in standard .280 Rem to be AI'd. Looking forward to seeing what the difference will be.

Frank N.