I have threaded cobras on my gear boat and they are nice, very strong but expensive and heavy. On my cats I use nrs bronze alloy. Five seasons of big water and I haven't had to tighten them in a vice yet.
Non-cobra bronze locks are very soft and loosen easily. Aluminum are too stiff and will crab/break oars. I use a hitch pin and cotter to secure. I make plastic washers to eliminate play. The plastic keeps the noise down also.