I prefer mine scoped though it turns an already heavy gun into a real beast. do pushups.
What type of M1a is it- loaded/match etc etc? Depending on what you have already there is alot of things a lowly commoner like us can do to play around and accurize. The most cost effective thing seems to be reloading though as these guns are ammo sensitive.
The springfield mount pretty much blows. Save yourself the money and hassle and get a name brand mount that is known by the community to be good.
Arms #18- Lowest to the receiver. Can obstruct ejection on some rifles. (I went with the arms 18) one of the lightest steel mounts
Basset mount- Best option for someone that wants to take scope on and off. Easily removable, still quite solid.
Sadlak- available in steel, aluminum. also solid.
Dont forget to put a cheek riser on that sucker.
Now that you're into the m14 game check out this site below- unbelievable wealth of info if you want to start messing with or just learn about the gun.