Using a marine 316 Grade Stainless Steel spring is the best because it will not rust. 304 Grade Stainless Steel has carbon content and will rust eventually when exposed to the outside environment. The standard springs are chromed / nickel plated mild steel and look great, but after a few days of the spring flexing, the plating flakes off and the rust starts.
The lock washers for the antenna sections supplied with the Antron 99 and the
I MAX 2000 are nickel plated mild steel. I assisted a local guy with assembling and installing a new (original 24-ft) I MAX 2000 and it took me forever to convince him to change out the plated mild steel washers with 316 stainless lock washers. He bought the stainless-steel lock washers at the local hardware store and they were 304 not 316. I sent him to the local boat marina to buy the 316 Grade lock washers. Oh my God! I thought he was going to have a heart attack when he complained of the cost for "two" 316 stainless steel washers.
I helped another guy disassemble an Antron 99 which he assembled and installed about two years ago because the SWR was climbing. He could not understand why the top section was "wiggling" where the two sections were joined. Sure enough, the plating on the lock washer had flaked-off and the washer was nothing but a piece of rust and about ninety percent disintegrated. There was a small amount of contact between the bottom and top sections. He installed a 316-grade stainless lock washer and was "on the air