BEIJI, Iraq - U.S. soldiers in the field were not all supportive of a Pentagon study that found improved body armor saves lives, with some troops arguing Saturday that more armor would hinder combat effectiveness.

The unreleased study examined 93 fatal wounds to Marines from the start of the Iraq war in March 2003 through June 2005. It concluded 74 of them were bullet or shrapnel wounds to shoulders or torso areas unprotected by traditional ceramic armor plating.

Soldiers from the 101st Airborne Division's 3rd Brigade "Rakkasans" are required to wear an array of protective clothing they refer to as their "happy gear," ranging from Kevlar drapes over their shoulders and sides, to knee pads and fire-resistant uniforms.

But many soldiers say they feel encumbered by the weight and restricted by fabric that does not move as they do. They frequently joke as they strap on their equipment before a patrol, and express relief when they return and peel it off.

Second Lt. Josh Suthoff, 23, of Jefferson City, Mo., said he already sacrifices enough movement when he wears the equipment. More armor would only increase his chances of getting killed, he said.

"You can slap body armor on all you want, but it's not going to help anything. When it's your time, it's your time," said Suthoff, a platoon leader in the brigade's 1st Squadron, 33rd Cavalry Regiment. "I'd go out with less body armor if I could."

The study and their remarks highlight the difficulty faced by the Army and Marine Corps in providing the best level of body armor protection in a war against an insurgency whose tactics are constantly changing.

Both the Army and the Marines have weighed the expected payoff in additional safety from extra armor against the measurable loss of combat effectiveness from too much armor.

According to a summary of the Armed Forces Medical Examiner's study obtained Friday evening by The Associated Press, the 93 Marines who died from a primary lethal injury of the torso were among 401 Marines who died from combat injuries in Iraq between the start of the war and June 2005.

A military advocacy group, Soldiers for Truth, posted an article about the study on its Web site this week. On Friday evening, The New York Times reported in its online edition that the study for the first time shows the cost in lives lost from inadequate armor.

Autopsy reports and photographic records were analyzed to help the military determine possible body armor redesign.

Of 39 fatal torso wounds in which the bullet or shrapnel entered the Marine's body outside of the ceramic armor plate protecting the chest and back, 31 were close to the plate's edge, according to the study, which was conducted last summer.

Some soldiers felt unhappy that ceramic plates to protect their sides and shoulders were available, but not offered, when they deployed for Iraq in September.

"If it's going to protect a soldier or save his life, they definitely should have been afforded the opportunity to wear it," said Staff Sgt. Shaun Benoit, 26, of Conneaut, Ohio. "I want to know where there was a break in communication."

Others questioned the effectiveness of additional body armor.

"It's the Army's responsibility to get soldiers the armor they need. But that doesn't mean those deaths could have been prevented," said Spc. Robert Reid, 21, of Atlanta.

Sen. Barack Obama, D-Ill., who was in Iraq on Saturday, said military leaders told him that body armor has improved since the initial invasion in 2003 and that the military hoped to gradually transition to the improved armor.

The debate between protection versus mobility has dominated military doctrine since the Middle Ages, when knights wrapped themselves in metal suits for battle, said Capt. Jamey Turner, 35, of Baton Rouge, La., a commander in the 1st Squadron, 33rd Cavalry Regiment.

The issue comes up daily on the battlefield in Iraq, and soldiers need to realize there is no such thing as 100 percent protection, he said.

"You've got to sacrifice some protection for mobility," he added. "If you cover your entire body in ceramic plates, you're just not going to be able to move."

Others in the regiment said the issue of protecting soldiers with more body armor is of greater concern at home than among soldiers in Iraq, who have seen firsthand how life and death hang on a sliver of luck when an improvised explosive device hits a Humvee.

"These guys over here are husbands, sons and daughters. It's understandable people at home would want all the protection in the world for us. But realistically, it just don't work," said Sgt. Paul Hare, 40, of Tucumcari, N.M.