Re: Fender's claim to their "Bullet" strings???
I've been using the Bullets for over 10 years on my G&L guitars with the Dual Fulcrum Vibrato. This Vibrato is a Leo Fender design, and while it is an improvement over the vintage Fender "Synchonized Tremelo", it uses a similar block under the bridge plate.
Fender Bullet strings come in their Pure Nickel, Stainless and Super Bullet alloy. The advantage of the Bullet end is two-fold: first there is no double-wrap needed to secure Bullet as on a ball-end string; and the smooth nose of the Bullet fits better in the string tunnel of the Vibrato Block.
With a ball-end string, frequently the doubled end-wrap will make contact against the apex of the string saddle and cause false harmonics, buzzing, and tuning instability. No double wrap--no problem.
A ball-end will twist and move in the sting tunnel, and sometimes get hung up temporarily on a rough area, again causing tuning instability. The smooth nose of the Bullet string simply fits better, and has very little chance of getting bound up in the Vibrato Block.
Bullet strings are designed for guitars with Fender-style Vibratos, and are not recommended for guitars with string ferrules in the back of the guitar (Telecasters); guitars with Stop Tailpieces (Les Pauls, etc.); guitars with a plastic ferrule block (ASATs); or on guitars with trapeze-style tailpiece (ES-175, L-5, etc.). Obviously, they won't work on guitars with Bigsby Vibratos--the Bigsby requires a string with a ball-end. Fender does market strings in the same gauges and alloys as Bullets, but with the traditional ball-end.
You may or may not notice better tuning stability with the Fender Bullet strings, but in my experience I would give them the nod in this regard. I have found them to be long lasting and very durable. Fender Super Bullets will continue to be my string of choice for my G&L Legacys, S-500s, and Comanches.
Bill
