Why US speargun use square cut sear tooth and Europeans used angled teeth.

[popgun pete]

It all dates back to early speargun history, as in Europe the spring gun was first out of the blocks and set the trend for all the weapons that followed. As the shaft was pushed by a long coil spring sitting directly behind the spear the first attempt used a single-piece trigger with a trigger pivot pin below the barrel tube and as that was very unreliable the decision was then made to use a pull down sear lever in the gun. Because they wanted to avoid pushing the spear backwards when pulling the trigger they angled the retaining tooth. If you use a long enough sear lever arm then it swings on a flatter arc, but there was only so much length available in the gun’s usually alloy grip handle, thus the tooth had to be angled, but never by enough to completely eliminate the problem.

Side slotted barrel band guns got rid of the long propulsion spring, but they kept that same trigger mechanism for both them and the next weapons revolution the French band powered Arbaletes, even though it no longer had a coil spring pushing over the top of it as had been the case with the compression spring gun. Le Prieur used something similar in his “declic” trigger.

Because in the USA they never started with the spring gun they used a single-piece trigger and they only work well with a square cut tooth. Some early US spearguns used the wishbone directly on the shaft tail and thus had no sear box roof, but that type of gun did not last long as securing the spear tail with a sear box roof was a much better idea. However such guns must use a square cut shaft tail or the shaft can pop off the tooth at the wrong moment

Of course Europeans also used single-piece triggers, but they were not as easy to pull with larger band loads as the two piece pull down sear lever trigger guns were and their spears were not as universal compared with the French Arbalete shafts. In the USA most guns used shafts with square cut tails until improved euroguns arrived in recent decades as formerly the guns were considered too weak being principally designed for reef work and smaller fish.

[Spear One]

Pete, we are for fortunate to have our own speargun historian! Thanks for sharing your knowledge with us!

[popgun pete]

Note that while they look vaguely similar the Beuchat is a single-piece trigger while the Cavalero Champion gun is a two-piece pull down sear lever trigger. The Champion gun was more widely copied than the Beuchat gun was because of that better trigger. Beuchat then made a two-piece trigger gun that used a star wheel sear lever which also required using an angled tooth for its spear tail notch.

[popgun pete]

When plastic grip handles replaced cast alloy gun handles the star sear lever also made it into those guns. The leverage advantage of a star wheel trigger is zero, no better than a single-piece trigger, but it had more teeth to spread any tooth wear over.

[popgun pete]

Originally Posted by Spear One

Pete, we are for fortunate to have our own speargun historian! Thanks for sharing your knowledge with us!

I thought that I should write it down before I forget as I am not going to be here forever and many things today we just take for granted, but they have a historical basis for being the way that they are.

[popgun pete]

There were a few spearfishermen in the USA who decided to follow the pull down sear lever used by the Europeans, the most notable being the Sampson gun. Another was the 1955 gun invented by Thorburn whose idea was to shoot directly from the reel with the shooting line and reel line being one and the same. His gun is interesting as it is integrated into a single tube body with bulkheads sealing some sections off as buoyancy elements, but you can see pulling the trigger will move the spear slightly backwards against the band pull. That and shooting from a reel is not a good idea as the reel spinning will add a lot of drag to the shot.

[popgun pete]

The advantage of the square cut sear tooth and matching spear tail notch is the load bearing area is much greater if the opposing faces press flatly against each other, but in practice they may not if the sear lever is tilted too far forward with the mechanism latched. Although we do not have the capacity to tune this a lot will depend on how accurately the levers were made and how horizontal the mechanism or its cassette sit inside the gun, or if the rear grip handle tilts on the gun barrel. Those keen enough could file the faces and hope most of their spear tail notches were cut square to the shaft axis.

[popgun pete]

In Australia very early spearguns were variations on the hinge gun which uses a friction trigger, much like the tilting washer on a modern caulking gun. This means the gun has no spear tail notch and can be cocked for the shot at any insertion length, many such guns were spear tail drivers using a mid-handle with next to no gun stock and a tail cap pusher on the spear.

These guns were replaced with single-piece trigger weapons like everywhere else, and that meant square tail cut spears, same as the USA.

[popgun pete]

The next evolution was the two-piece cam lock trigger which had the advantage of using existing square cut tail spears, the most famous being the Undersee trigger mechanism invented by Denny Wells. Another was that used in the Lyle Davis gun, this being a formative period for all modern band spearguns. The sear lever now rotated separately in a sear box with a roof and floor so that the spear tail was wiped off the rolling sear lever tooth and the spear was allowed to fly from the gun.

[popgun pete]

Australian Wally Gibbins with assistance from John Lawson crafted a reverse trigger mechanism that used the principles enabled in the Denny Wells trigger mechanism, but had a completely closed sear box, not just a partial floor.

The importance of the sear box roof and floor is the former stops the spear tail jumping the sear lever tooth and the latter wipes the shaft tail off the descending sear lever tooth as it rolls forwards. The significance of this floor will be revealed later.

[popgun pete]

In Europe not to be outdone speargun makers decided to also use a two-piece cam lock trigger mechanism and a variation on it where the sear lever tooth was pushed aside for the gun to be latched. The latter was a novel idea, but not foolproof. These guns all retained the angled sear tooth and the wide rectangular mouth sear box. The wide mouth let the tail end shaft stops slide in and the flat sear box roof allowed the spear tail to ride up on the angled sear lever tooth. Without a sear box roof these spears can jump the tooth. The upward pressure loading can also wear the roof out, but will take a long time to do so. The flat top tail ends on the spears prevented the shaft rolling in the sear box.

[popgun pete]

At some time the Europeans realised that the shaft tail stop lugs should no longer enter the sear box, but instead be relocated to in front of the shaft wishbone notches, that way the shaft would avoid being snapped off with a big fish fighting the shooting line levering on the wishbone notches. This was soon the practice everywhere on all shaft types. Tradition left the rectangular sear box mouth in place, the gap either side of the shaft tail could now allow a line loop tied to the extreme shaft tail. Snapping shaft tails off soon eliminated this practise, unless the prey was small.

[popgun pete]

The Sea Hornet and its Biller counterpart had been the only reverse trigger mechanisms in widespread use when many manufacturers decided to also use this arrangement, but to flatten it they nearly always changed it from cam lock to frame lock. That meant the cocked to shoot gun could not revolve the sear lever because they jammed the front edge of the trigger against a cross bar in the housing frame. This works OK, but then they made a big mistake. To improve speargun mechanism gearing they moved the main pivot pins further apart and that allowed a very long sear lever. However they abandoned the sear box floor that allows the spear tail to be wiped off the shaft tail. You can guess what happens next, the shaft tail does not always pop cleanly off the sear tooth and can cause the spear to jump out of the gun. Accuracy of shooting can now go out the window.

One manufacturer used the reverse trigger mechanism as it was originally intended in the Ultimate speargun, ultimate by name rather than excellence. The guns weigh a ton!

[popgun pete]

While spear rolling in the sear box is not a problem if you use hard wire wishbones, the square cut spear tail manufacturers employed a number of anti-roll features on their shafts. The Voit/JBL guns use flats either side of the spear tail, Riffe and others use a flat on top of the shaft tail and Biller/Sea Hornet and Ocean Rhino use a short vertical slot in the extreme spear tail. When you see these features you can nearly always identify a shaft through using this “fingerprint”.

[popgun pete]

Folded metal sear boxes used in timber stock guns often have a short run of the shaft to the spear guide track built into the gun body, so the shaft tail can still be wiped off the descending sear lever tooth. However if the shaft has a long run to a shaft guide track, or none at all, then the shaft tail can pop off the tooth. On the Sea Hornet and Biller guns the shaft tail rides in a long tunnel compared with other guns, so there is both a roof and a floor even if the gun has no shaft guide track. The shaft tail slot sits on either side of the sear lever backing projection with the gun cocked to shoot. Ocean Rhino guns even though they now use a standard trigger mechanism have long sear box tunnels and a guide track, the best of all worlds.