Quote Originally Posted by muchmoore
Just buy your own bag or get a weight set.
Its hard to develop all of the muscles you need to punch and be able to get the muscle memory and twitch that your body preforms with just weights so their not really a proper substitute for a heavey bag really, not that its a bad idea just theres more to a punch than the strength of your muscles (not that it isn't a factor)

I reccoment biting the bullet and buying the bag, it'll pay for its self and as missy said even a second/cheap one is better than most of the alternatives you can make