you can't get 29 rounds that way,you have to rework the 33 round mag.
pat
my mag with the TF extension holds 29 rounds, with room to spare (with no modifications at all). it wouldn't take much work to get the 30th round in there.
Have you checked to see if they fit in the 170mm gage,we had a shooter with one like yours fail.
That is why I have been using the cut down 33 and make it fit the gage.
Of course he might have done something different than yours,but he did say his was a stock 17 round with the plus 10.
That gage is tricky,I bought a gun with some mags and they would start into the gage but would not go the bottom as they are suppose to fit.
pat