I was thinking of lee moulds due to price and tumble lube feature.Does anyone have any experience with these as far as grouping ability as compared to other cast bullets, leading, or any other differences? I will be mainly using these for practice in S&W 629 4"and 6 1/2. Any info you have greatly appreciated.

I don’t have any experience with conical bullets, but my Dad and I have loaded thousands of round balls using Lee molds. Good stuff as far as I am concerned.

Your leading is going to be as a result of human error.

Lees quality is pretty inconsistent on their bullet moulds. You can use tumble lube on any cast bullet, so there's no real advantage to Lees microband design. If you are planning on shooting full powered loads from your 44s you will likely want to use a gascheck style bullet, and those aren't offered in the "tumble lube" design. I can recommend a couple of good websites if you're interested. Leading is almost always a sizing or lubrication issue, a properly sized & lubed bullet, fired through a clean bore (no jacket fouling), will not lead the bore.

After staying with Lyman iron molds for several decades I ventured into Lee aluminum gaschecked molds but couldn't get the gascheck rings to hold the gaschecks on? I tried varing my lead temps and adding 2% tin but, no help. Quickly dropped using gaschecked Lee and went to other plain based aluminm LBT molds and haven't looked back.
Steve