Sheryll Murray, MP for South East Cornwall, has raised concerns about the kit Royal Marines of 42 Commando, who are based at Bickleigh barracks, near Plymouth, have been issued with in preparation for deployment.
Royal Marines of 42 Commando will take over as lead Commando this year, which means they could be sent with just two to five days' notice, should an emergency arise anywhere in the world.
The Conservative MP has raised her concerns about the kit with Defence Minister Mark Francois, pointing out the equipment they could use on operations is different.
It follows the return of Mrs Murray from a fact-finding trip to California, during the parliamentary recess, where she joined members of 42 Commando on exercise. Mrs Murray, who paid for the flight to California herself, learned that while many of the men were training with the old-style body armour, on deployment to Afghanistan they had been using the up-to-date Osprey body armour.
Some of them have had to hand it back on their return home, according to Mrs Murray. The MP said: "In the event of an emergency deployment whilst operating as the lead Commando, they would be issued with the new style Osprey but because they rig their webbing and equipment in a different way whilst wearing the different body armour this is causing them concern."
While they accept the priority must be for troops in Afghanistan, they feel the reduction of personnel in the conflict should allow them to train with the equipment they would use on operations, she said.
This is important because integrating their equipment into the different structure of the new body armour takes time, Mrs Murray was told.
A Ministry of Defence spokesman said: "Osprey body armour and plates are prioritised for personnel serving on or training for operations in Afghanistan.
"As 42 Commando's recent training in California is routine and not related to a specific deployment, they have been using different protective equipment. However, this has no impact on their training or preparedness for operations."
The MoD spent £16 million on the new Osprey armour to improve the odds of surviving bullets or shrapnel.
Body armour has been a highly sensitive issue ever since Cornish tank commander Sgt Steve Roberts was shot dead in Iraq in 2003, days after being ordered to hand in his armour because there were not enough sets to go around.
