Sizing gold so one bad scalp can't wreck the week

[FXS London Scalper]

On XAUUSD the danger isn't the average move, it's the occasional one. A spike of several dollars within seconds happens on data, and stops can fill well beyond where they sit.

A sizing approach built for that:

• Size off a stress loss, not the planned stop. For example, assume a stop could fill twice as far away on a news minute, and make sure that loss is still acceptable.
• Cap gold risk per trade below your FX risk, say 0.5% instead of 1%.
• Set a weekly loss limit for gold separately from FX.

A worked example: a $3 stop on 0.3 lots risks $90. If a fill comes $3 beyond the stop, the loss is $180. If $180 is more than you'd accept on one trade, the size is too big, whatever the planned stop says.

Your own data can set the multiplier: from your history, find the worst stop slippage on gold and use something above it.

This feels over-cautious until the first bad news minute. How do you size gold compared with FX?