This is the rule that I think applies.
"must be worn at waist level"
However I am not a CRO.
5.2.3 Unless otherwise specified in the written stage briefing the competitor’s equipment belt carrying cartridges (in caddies, loops, clips, bags or pouches) and/or detachable magazines and/or speed loaders must be worn at waist level. "Chest-rigs", bandoliers and similar carriers are expressly prohibited. Additional ammunition carriers mounted on forearms are permitted provided that cartridges are carried individually in loops or clips.
5.2.3.1 Not applicable.
5.2.3.2 Only one equipment carrying belt is permitted. Cartridges held in loops or clips on the belt are restricted to a maximum of 170 mm total height. Rounds carried in caddies (often known as "strippers") must not exceed 6 rounds in height.
5.2.3.3 The Range Master may make allowances for variations to Rule 5.2.3 due to anatomical considerations. The Range Master's decision on conformity to Rule 5.2.3 is final.