257+P Bob vs 257AI

rbursek · October 18, 2011, 10:51 AM

In the late 80,s I made up some 257AI for myself and my sons, but now with the regular 257 +P loads is there any real advantage to the 257AI, In Noslers load info there is only about 150fps differance betwee the AI and the Bob which when I emailed Nosler, the Bob data is for a regular Bob not the +P's, I can not seemed to find load data for a +P load except to look at Winchester's catolog specs for the 257Bob+P.
Any help here from the pros would be appreciated.
TIA,
Bob

black mamba · October 18, 2011, 11:04 AM

The AI version should give 50-100 fps more than the Roberts at the same pressure, whatever that is in +P (should still be under 62k psi).

I shoot a .35 Whelen AI, and the main benefit for me over the standard round is lower pressure and longer case life with the sharper shoulder, which almost eliminates brass flow into the neck.

rbursek · October 18, 2011, 11:51 AM

Ya, the case life and lack of trimming seems to be the only advantage, other then an extra 100fps give or take with what bullet weight being used, since they came out with the +P level.
Bob

October 18, 2011, 10:51 AM	#1
rbursek Senior Member Join Date: March 30, 2011 Location: Milwaukkee, WI Posts: 152	257+P Bob vs 257AI In the late 80,s I made up some 257AI for myself and my sons, but now with the regular 257 +P loads is there any real advantage to the 257AI, In Noslers load info there is only about 150fps differance betwee the AI and the Bob which when I emailed Nosler, the Bob data is for a regular Bob not the +P's, I can not seemed to find load data for a +P load except to look at Winchester's catolog specs for the 257Bob+P. Any help here from the pros would be appreciated. TIA, Bob

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October 18, 2011, 11:04 AM	#2
black mamba Senior Member Join Date: September 13, 2011 Location: SW Florida Posts: 890	The AI version should give 50-100 fps more than the Roberts at the same pressure, whatever that is in +P (should still be under 62k psi). I shoot a .35 Whelen AI, and the main benefit for me over the standard round is lower pressure and longer case life with the sharper shoulder, which almost eliminates brass flow into the neck.

October 18, 2011, 11:51 AM	#3
rbursek Senior Member Join Date: March 30, 2011 Location: Milwaukkee, WI Posts: 152	Ya, the case life and lack of trimming seems to be the only advantage, other then an extra 100fps give or take with what bullet weight being used, since they came out with the +P level. Bob