1300 rounds????Thats nutz!
1300 of 22 maybe????? Thats about 10 lbs.
4-6 lbs per 100 for rifle calibers. 52 to 78 lbs !!!
Add rifle(s) and magazines......
Add some twinkies,2 packs of Ramen,2 bandaids and a compass....he's done! 
Yeah, definitely need to see the round.  A 30-round magazine of 5.56 is 1 lbs, so you're looking at ... 43 lbs?  Ammo alone?  (for an AR platform).  If you're talking 30-06 or something that size, definitely heavier.
I mean, if you're using it, your load is going to lighten, but you'll be a big target and probably won't get past that first magazine.
You'll make someone a nice cache, though.
So speaking of acronyms, what's MUSHY?