
How to do it:
1. Open up a map in HMT
2. Extract the antr tag for the assault rifle fp
3. Open the tag in any hex editor
4. Go to the offset 'B7'
5. you will see 03 00. change that to 0B 00 (that's right, you only edit one nibble
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6. Save and inject the meta back using HMT.
7. Test it out in game, there will be a brand new assault rifle melee animation. Instead of swinging forward with the butt of the rifle, master chief hoists the gun upwards then smashed it forwards. edit: vid: http://youtube.com/watch?v=JZKFR1NQcVw
Perhaps I will write an HMT plugin that will do this for you... but it's Christmas and I'm lazy so right now you can do it yourself, It's just one nibble!
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Hope to see this in upcoming mods.