Not just about weight but also about balance
There are many things you can do to mess up the balance of your M4 Carbine. Most people I know that own an AR15 rifle now are toting an M4 Carbine variant and it is rarely an A2 version. Just about everyone know has a fore grip on their guns, but in all honesty most of those never seem to feel right. I have always been use to the traditional AR15 rifle and never felt the need to put a vertical grip on them but I have recently become a fan of the Mapgul Angled Foregrips. Sometimes it take a good training course to really test your gear out and many times it means adjusting the stock you have or moving the foregrips forward or back.
I have seen numerous times that guys ended up with failed gear or ended up taking some gear off of their Carbines by mid-day. Some of best training I have done was by a teacher that told us that we could not drop gear or take it back to our car, we had to leave all of are accessories and even magpul pmags with us or in a bag. It was an important lesson about not over packing and thinking about what you really need to use. There is no reason to load up 13 pmags when you probable won’t need that even if you’re going to shoot that many rounds, 6-8 magazines is a lot and speed loaders and boxed ammo is an easier way to pack.