Need some suggestions on load data for 150,165 and 180 grain bullets for a 20 inch barrel. New gun just bought today, never loaded for this kind before any help is appreciated. Thanks in advance.

Check out AR15.com or in Reloading books under 7.62x51 or M1A (I believe Hornady and Sierra have info under either one of those headings)...it is extremely important that you pay attention to the pressure curves when reloading for a gas operated semi auto.

Last weekend we took my friends new Armalite AR-10-a2 out to the range for break-in. He had mounted a Redfield 1-3/4 x 5 scope on a carry handle mount. After shooting a few rounds to check the irons, we got down to business. I had the first batch that I had found of the Aussie surplus 7.62 that has been coming in so reasonably priced. The first 5 shot group came in at 3/4" and I was a little surprised. I let the barrel cool for about five minutes and proceeded to shoot a 5 shot 5/8" group. This was from the bench at 100 yds. I shot it in my pet HB bolt and it shot around 1-1/2" which is not too bad for surplus, but that AR-10 shot it like match ammo. If your interested, the headstamp is AFF-90. It sells at most gun shows for around $140 per 800 rd. case.