The hand press might be ok for the 303 but I don't think you would be satisfied with the results for your AR. With a bolt action neck sizing is not only sufficient but often desirable for accuracy. However for reliable functioning in either semi or full auto you need to do a full length resize on the case. These tools are also incredibly slow, you would spend far too long loading and little time shooting. What they are nice for is load development while at the range.
If you want to get a start in reloading I would suggest spending a bit more and start right. The Lee 50th Anniversary Kit would give you a good start in reloading with little else to buy but components although I would recommend a hand priming tool and a brass tumbler. I have tons of brass so for me I can take things easy in stages but you can do this with the brass you just shot as well.
1. tumble the brass, you don't need to make it shiny new but just clean it.
2. deprime and size the brass on press.
3. use the hand primer to prime all the brass at on time. You can do this in your easy chair.
4. powder. The kit comes with a scale and powder measure, set the measure to the desired charge and charge all of the cases. A homemade loading block helps greatly here. Just a piece of 2X4 with holes drilled in it.
5. seat and crimp the bullets.
Reloading can be both fun and a money saver...unless you allow it to become a compulsion and then you end up with a reloading room that looks like this....
In all seriousness I would be more than happy to help in anyway I can with your reloading project. You can send me a message and I can go though everything with you step by step. As you can see in the pic I serious about my reloading...there are a couple press on the bench that are not in the pic...lol.