Reply To: Chidushim on Daf Yomi

ברכות כו,א

The RMA SA O’CH 89,1 says that we can’t daven shacharis after chatzos. The question is, as davenen is based on the tamid and mincha starts at 12 1/2 hours when nightly tamid starts, what about davenen shacharis in the half hour from chatzos until mincha starts? The MB s’k 7 there discusses this.
In reality mincha starts from chatzos (according to the GRA, who says on the first mishna in the masechte that speaking in plural, nights means after chatzos when sun turns west and the shkia) but chazal had us wait an extra half hour to be sure to daven mincha the proper time, therefore we should not daven shacharis then, rather daven two mincha shmonei esreis for makeup. If we already davened shacharis then, we don’t have to repeat it.