https://finance.zacks.com/rules-trading-stocks-ira-account-4427.html
No Free Riding
A stock trade takes three business days to become official, or "settle." When you sell stock, the cash is not officially in your account until the settlement date three days later. You can buy stock with unsettled cash, but if you sell that stock before the original trade settles, you are guilty of violating the Federal Reserve Board's Regulation T, commonly called free riding, on the cash that is not yet yours.
Free riding is not allowed in cash or IRA accounts. The result of the free riding rule is that you cannot effectively trade short-term – less than three-day holding period – in an IRA account.
Additionally if you think you see a loophole, it probably can't be done. That's where the REAL money is made.