29s flat. That is unaimed fire, preping the next mag in hand, dropping mag using the button, slamming in the new one, hitting the BAD lever to cycle the bolt, then recomencing fire while picking up the next mag. Theorectically I should be able to do it in closer to 27s. I will leave that to Jerry. This is all using my CED7000 shooting timer. Mainly the issue at least for a competition shooter like me is getting 150 rounds of something that does not have any duds or feeding issues. So out of any random number of tries, say 5, I find I can only have 2 clean runs.
29s is actually an extrapolation since I only have 5 mags, but I have done that in 24s flat. I am shooting off the 25 rounds in a hair less than 4 seconds and doing it the way I said I can do 1s mag changes so each mag and swap totals 5s each give or take a little. At a recent S&W sponsored event I was shooting off about 100 rounds of aimed shots in a little over 40 seconds (70 steel knockdown targets, some only 1.5" wide) And I did not finish first either. That is 4 full aimed mags hitting with almost 18 of 25 rounds.