22 br

i have seen that Jim STEKL use n203 in the 22 br and 52 grain reminton br bullets to set a record with.now i see that 203 is n longer avalable to use.what in your opion wound the nexk best powder forthis load be.i would like to get n 135 for it.
thank you for your time
Do you have the early Remington chamber or the later long-neck chamber based on the Lapua cases?