One important point no one has brought up is pin to hole clearance. We all know a clevis pin must be the right size for the hole it is fit into to avoid failure and maximize the contact surface area of the clevis pin to the hole in say the chain plate.
I don't like rings and neither does my rigger. Why? Pins are very hard to find in the right wire diameter for the clevis pin end holes they are intended to fit into. These holes need the proper size coter pin and that's easy as coter pins come in many diameters. A cotter pin or ring sized too small for the clevis pin hole IS a potential failure point!
I never reuse a cotter pin and I would never re-use a ring. Talk about being "penny wise pound foolish". My entire lifetime supply and assortment of stainless cotter pins cost me about $35.00 over seven years ago and I still have a LOT left.
The most important thing to consider when installing cotter pins and or rings is the fit in the hole. The pin should be as large as possible yet still fit into the hole.
Years ago I had a goose neck failure on my boom because someone at the factory used an undersized cotter pin that slopped around in the hole until it failed. I replaced it with another cotter pin, of the right size, and it's still going strong over ten years later. In fact I just passed my old boat while sailing yesterday..
I have yet to see a properly sized, bent and taped cotter pin fail though I'm sure it could happen. I have seen one ring failure due to it being undersized..
halekai36, I agree that size is important.
However, I have been using circular pins for many years and have never had anything happen that could be remotely attributed to a properly used circular pin.
I come across clevis pins now and then with holes so small that you need a tiny little cotter pin. I toss em.
I like a heavy duty pin or ring but not a tight one. I install stuff with the thought in mind that I am going to be the one having to take it apart again.
The problem with close tolerances with cotter pins is that sometimes it's a real pain to get them straight enough to remove. I've even had them gall and ruin clevis pins.
C. Sherman Johnson, (csjohnson . com), has just about every conceivable clevis pin, cotter pin or circular pin that you would likely ever have a need for.
And I bet SailNet is still a dealer for them.
This is pretty much how I always pin a turnbuckle.
The three circular pins on the right in the picture below are pretty much all I have ever had a need for. They are from smallest to largest the CSJ R-2, R-3, and R-5. The R-5 is so stout that it's tough to open with a thumb nail. I usually have to use my Leatherman to get it over the body of the turnbuckle.
The one on the left has a little pig-tail. Which in my opinion kinda defeats the purpose if you are looking for something that won't snag. I won't use those. However many products such as blocks come with them new. I don't usually remove them.
I also agree that it is not smart to reuse a deformed pin, straight or circular.