Hi WayneConrad,

Shirt - http://www.orvis.com/store/product_choic...;subcat_id=6224

or http://www.west-winds.net/ventile_shirts.htm both are cool in the heat and warm at night time.

Undervest - http://www.springfields.co.uk/clothing/underwear-socks/?id=796 or similar. The secret weapon to keeping cool cool

Trouser - http://www.genuinearmysurplus.co.uk/pages/products/makes/detail/rowid=547 - zip off trousers are OK but can be uncomfortable shooting in the prone position. Genuine US BDU trousers in OG or Tan are OK and easier to get but may not be as cool in warm weather.

Hat - http://www.ima-usa.com/product_info.php/...4b211078b8929c7 - keeps the sun off the neck.

For night time cold conditions a heavy merino wool sweater such as this at http://www.davidgoldie.co.uk/acatalog/copy_of_copy_of_Orkney_Sweater.html will keep you warm.

For cold wet conditions then Goretex shell over trouser and jacket may be worthwhile. Goretex Paclite and XCR jackets and trousers are generally available but sometimes difficult to get in subdued colours. Fjallraven and Norrona Jackets might be difficult to get in the US.