YUMA PROVING GROUND, Ariz.-- The M113 Armored Personnel Carrier and its variants are iconic vehicles in mechanized infantry history.

First fielded in 1962, the M113 was ubiquitous during the conflict in Vietnam and has seen service in virtually every American military action in the ensuing decades. Though largely surpassed in both use and operation by the M2 Bradley, variants of the M113 continue in operation to this day.

Nonetheless, the M113 was built for a different generation of warfighting, and the recently developed Armored Multi-Purpose Vehicle (AMPV) is intended to dramatically increase Soldiers' transport capabilities. The AMPV's five variants--a general purpose vehicle, mission command vehicle, mortar carrier, and medical evacuation and treatment vehicles-- have nearly 80% more interior volume than their predecessor, and significantly more power and survivability. Cooling and electrical systems are also upgraded to accommodate both existing and future upgrades.

All variants of the vehicle are slated to undergo extensive testing at U.S. Army Yuma Proving Ground (YPG).

"We have a wide array of testing going on in Yuma," said Shelton Raine, program manager. "We'll be doing all the mortar firing on the mortar carrier variant as well as reliability and performance testing on the other four variants. We're trying to do a lot of testing in parallel to meet a very aggressive test schedule."

Presently, the mortar carrier variant is being tested by YPG's Munitions and Weapons Division.

"We're verifying the integration of the M121 mortar system on our vehicle," said John Portaro, mortar carrier test lead. "We want to ensure there are no surprises and everything functions normally."

Integrating the 120mm mortar into the vehicle took extensive work and requires a punishing test fire regimen to insure the system performs as expected.

As they do so, testers pay close attention to the effects of firing each round.

"The M113 mortar carrier weighs about 30,000 pounds," said Chad Bloomingdale, test officer. "This vehicle is 80,000 pounds. We're conducting all this testing to see if that has any effect on performance or firing."

YPG supports the test firing with a wide variety of personnel, from weapons operators and observers to high speed camera operators, data collectors, and conditioning chamber personnel. Some of the test rounds are conditioned to various temperatures and brought to the mortar immediately prior to being fired.

"Yuma has the infrastructure and tough environment to really stress the vehicles and give us a more thorough test," said Raine. "It gives us confidence in its technical maturity coming out of this phase."

The test firing of the mortar carrier variant is only the start of evaluations of all aspects of the AMPV's performance that will last for more than a year.

"We get excellent support at YPG," added Portaro. "Everybody here will go out of their way to do whatever is necessary to get the job done. We work together really well."