Re: Minumum barre length to get to 1000 with a .223
The other HUGE problem you'll have with a .223 PSS is which barrel it has. They switched from a 1:12 twist to a 1:9 twist (don't recall exactly when), but with a 1:12 twist running lighter bullets that will properly stabilize from a shorter, slower barrel...you are asking a WHOLE LOT to get to 1k.
Plus, with the 1:9, you may not be able to stabilize heavier than 68-69gr bullets which is another mark against the rifle for getting out to 1k. Even if you have been able to stabilize heavier 75gr bullets thus far (which are better suited for extended ranges...along with the 80-90gr pills), shortening your barrel, losing MV, you may not be able to continue stabilizing them.
Anyway, like folks have already said, 20" would be the minimum I'd want to cut it down to.