When you edit an animation, it overwrites the animation that you were editing unless you press create new animation - which starts you from scratch, which is usually a lot harder.  Try not to use the entire "soldier_animations.xml" - it's just too large and unwieldy to be workable.  Here's my layout of the soldier_animations file (which I've renamed to "b.xml" to simplify the command prompt message):
Code:
<animations>
    <animation loop="0" end="1.140000" speed="0.500000" comment="reloading, flip left, revolver">
        <frame time="0.000000">
            <position x="-0.995668" y="55.551552" z="0.164213" />
            <position x="-0.654966" y="48.573368" z="0.598787" />
            <position x="-6.517905" y="45.624840" z="4.576976" />
            <position x="5.190133" y="45.112663" z="-2.849375" />
            <position x="-6.021244" y="44.230759" z="12.450706" />
            <position x="8.693733" y="38.104336" z="-4.461673" />
            <position x="-6.021244" y="44.230759" z="19.488283" />
            <position x="9.725967" y="31.149961" z="-5.217430" />
            <position x="-1.077580" y="35.322517" z="0.874707" />
            <position x="-5.124651" y="28.351248" z="3.696151" />
            <position x="3.416056" y="28.409811" z="-1.517928" />
            <position x="-8.219771" y="13.917140" z="6.340977" />
            <position x="5.728513" y="13.643060" z="-0.495910" />
            <position x="-9.471902" y="1.083165" z="7.948585" />
            <position x="6.962823" y="0.725944" z="-1.286222" />
            <control key="magazine" value="0" />
        </frame>
        </a_whole_bunch_of_frames_later>
    </animation>
</animations>
It's a single animation that makes the process simpler and more direct.  Just use the left and right arrow keys to cycle the frames and edit them.