Serendipity  is an  Expert Advisor tat designed for scalping on M15. Work Chart is EURUSD M15 but you can test it buy yourself on  other currency pairs

parameter 

• MagicNumber - EA identification code to avoid interference with other EAs.
• Risk  - Automatic lot calculation.
• Spread - maximum spread for trade.

Suggestion

I had test it with Risk around 10%~~20% and maximum spread value on test is 5, The total came out very well. But if you can endure higher maximal drawdown then you can use higher risk.