As far as I know, WinSPMBT stores the sounds internally with the unit. In other words, you'll have to replace/repurchase all units using the Mosin carbine 44. Then the correct sounds will be used.
If you change a rifle sound you should build a simple test scenario and ensure that the unit you changed is bought. The way to do that is rename it or add a ** to the name so you know you ar buying the unit you changed the sound in. What frequently can happen is you buy a unit that hasn't been changed then when you run the test it's the old sound. Changing the name is a simple way to ensure you have the one you want. The new sound SHOULD play for you IF you have it entered into the sound ini file exactly like the others
Don
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"You are never to old to rock and roll if you are too young to die".--- What do you expect to be doing when you are 80?