So I put on my blow down fitting w/ the burst disk slipped on it and set my tq wrench at 15 ft lbs and went to tighten it... unfortunately it must have clicked right as i started turning and I didn't hear it, so I went about a half turn past 15 ft lbs before I realized it should be tight enough by now.

Does it matter that I over tightened it?

Also, is the standard disk HSW sends w/ their kit 3000 psi? The disk I pulled out of the bottle was clearly labled '3000 psi', but my new HSW disk said like 775psi from what I could read?

 

It should say one of the following 3k, 3000, 3.0k. Also, usually if you overtighten them it stretches the disc causing it to burst even when filling. I think you will be fine because it doesnt sound like you went to far with it.