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modifying the Biller 54

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New Member
Jul 19, 2004
I am starting a thread dealing with preparing and customizing the Biller 54 for more reliable shooting of mid range game fish including the white sea bass (inshore) and various offshore or reef game including king mackeral and pompano. I have a lot to say on this subject and intend to parse the elements and illustrations as I go along. I would be gratified if anyone should find this useful.


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Biller 54

The teak model of the Biller has the potential to be a fine gun for shooting game fish. However, there are several deficiencies to be overcome. Many of these have to do with the arrow which must be customized for true flight. In the picture above is shown three rubber bands with custom wishbones attached to a 'flight tab'. Originally, as designed by Potts/Prodanovich, these were made to fit 3/8 shafts. However, as I will discuss it is fairly easy to fashion facsimiles of the tab for a 5/16 blank shaft. The tab is made by slicing lengthwise a thick wall piece of 3/8 tubing, bending and filing to shape. The finished tab is welded to the hardened steel arrow and back filled with a small amount of solder.

The front of the tab must be true as it is impacted by the special slide ring (which will be discussed later). In other words it must be square with the shaft. The welds are done on each side but never in the front. The welds have absolutely no bad effect even if the shaft is already hardened. Well, rarely, if too much heat is applied, the shaft will bend. This can be easily straightened because of memory. Better to affix the tab to an annealed shaft, at least theoretically. In the end it doesn't matter. I suggest special ordering hardened Biller shafts with the sear groove in place but no crimp, no threads and NO sling grooves. The reason for ordering Biller steel is quality. You can depend on the hardest and most resiliant metal. If this is not practical, special orders can be made to 'Spearcrafters'. The shaft length must be standard length. I do not recommend very long shafts as these can adversely affect the speed and accuracy.

The tab will hold three wishbones. For some reason the photo looks like there are two bands attached but there are three, I promise.
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The wishbones (bridles) are made from 19X1, 3/32 stainless. The ends are lead balls. These are fashioned in the following manner. Cut a length of cable 6 1/2 inches. Bend the cable. Prepare a mould by drilling a 5/16 hole in a small block of alulminum. Fill the mould with radio solder, the kind with resin core. Dip the cable end in acid flux made for stainless steel. Dip and hold the cable end into the solder. Raise the torch so that it momentarily touches the cable which will cause the solder to creep up the cable giving good wetting of the cable. Remove heat. Remove cable the instant that the solder hardens. If you wait too long the lubricating effect of the resin will be lost. soak the wishbone in acetone to remove the resin coating sticking to the lead balls.

The flexible wishbone is necessary to place the force in line with the arrow as much as possible. The rubbers must not be splayed out as with the Biller wishbone and some Euro wishbones. This causes rubber vibrations and makes the gun more difficult to grip. Strings and stiff heavy wire are either too fragile or too bulky and subject to water resistance when in motion.
Muzzle and slidering

Pic of muzzle


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In order to allow passage of the flight tab the muzzle must be cut back slightly. Using a hacksaw, carefully cut off the crown. Using a rasp, adjust the muzzle opening as follows: The opening must be large enough to allow the tab to pass through and small enough to capture the slide ring. The Biller slide ring is junk. The slide ring in the pic is a JBL wound SPRING HARDENED steel type which absorbs shock and will last many years. Take the slide ring and gently grind a flat into the back end. Check to ensure that the modified slide ring fits flush against the shaft flight tab with no gaps.
Slip tip made by Wally Potts
using mods suggested by
Wes Andrew


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This particular tip was made by Wally. Originally, Wally made his twin fluke tips with the flukes at right angles to the string hole. They did not work very well. Wally made a fabulous single fluke tip but one had to adjust aim for the deflection of the arrow which occurs with all single fluke designs. This mod, made in collaboration with Wes, a Naval engineer, is arguably the best ever designed. I will be discussing this at length and also provide dimensional sketches.
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Before I do the other thing, a word about Biller spearheads, a strange menagerie indeed. One can separate the lineup into two categories, Biller made and those acquired from a second source. The second source heads are made of 304 stainless and encompass fixed double wing, detachable double wing, single wing and stem points. These are all too soft for use around rocks. Hardened tips are available but the shanks will bend rendering them useless. The stem point is a joke as it will react to the guns recoil and turn sideways before it reaches the fish. If you absolutely have to have a fixed point or detachable, get the JBL rock point with hardened shank.

Now, the Biller home mades. There is a hardened steel spinner which has two wings. The shank is set into a soft steel receiver.. After about 5- 10 hits on big fish the receiver will be so wopped out that the shank will wobble back and forth rendering it useless. The rest of the homemade lineup is a strange collection of single fluke slip tips and oddly conceived detachable Tahitian style heads.

However, on the plus side, the Biller Tahitian shaft is excellent, if modified properly. Eventually I will discuss Biller mods for spearfishing Florida and the Indies. This shaft will be featured.
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how about the dangers of loading this type of trigger with more rubber than it was designed to take????
oh yeah the slip tip was invented by the Eskimos...
better effort this time around though:)
What only two pages! Just kidding . I'm glad you decided to show us some of your modds.I have a couple of ? about your biller,How many bands do you think the trigger mech can hold safely and what size bands are you currently using?How does the trigger
pull feel?I am in the process of building a gun using sea hornet parts and I think the trigger mechs are somewhat similar.

keep it coming:) AJ
waverider, OK, I'll take a break and answer some questions. The Biller trigger is an improved version of the Sea Hornet 'drop sear' and is very strong. It will easily handle three 9/16 rubbers of 120 pounds each. The trigger pull does not vary with load. However, there is a friction point with the line release. If the shooting line is strung too tight the trigger will exhibit resistance.

The number of comments and questions concerning the Biller trigger/sear is puzzling. By comparison, the Riffe will hold up to 1000 pounds, the Biller about 500. I will be discussing the rubber loads and accuracy in due time but I am not at all concerned about the trigger and sear as such. The Biller is a superbly accurate piece but who would load it to 500 pounds? Well, Biller was getting the same questions. At one point he made some sear parts from hardened 17-4. I don't know if he still does. I doubt that the plastic in the grip and stock extension would hold up under really heavy loads. The plastic would bend or warp. The all wood Limited could be substituted but the whole idea of loading up an elegant little gun like the Biller is ill advised. The gun responds well to finesse on the part of the hunter, not brute strength.
A light weight and subtle weapon like the Biller speargun should not be straddled with a trailing line and float. During the 1983 trip to Guadalupe, Terry Mass employed a large home made gun and float line to land the world record blue fin. This is the specific purpose for which such rigs are intended, trophy hunting. There is an exception, that is in Hawaii where local divers are afraid of attacks by Tiger sharks. Consequently, they trail a life guard float with stringer attached. When they spear a fish they 'climb' the float line back to the surface. Some divers feel the need to trail a boogy board and flag. Some of these are quite elaborate with carry harness and other attachments. To each is own. The average diver can successfully land fish up to 100 pounds or more with just a reel. Most fish, when speared, will sound but tend to plane off when the reel is triggered and the fish no longer feels resistance. They then swim off at their normal cruising depth. The resistance of the divers body is considerable and will tire the fish quickly. Free divers using reels should wear a UDT CO2 vest. If the fish manages to dunk the diver the vest can be inflated to act as a counterforce. Otherwise, a CO2 float can be attached to the gun itself. Some of these arrangements use breakaway rigs in which the line and float deploy and follow the fish. It is up to the diver to decide what kind of hunt he is on. One doesn't shoot squirrels in an elk camp and vice versa. Generally, the Biller is used to land fish in the 5-50 pound range. This includes a wide variety including Pacific yellowtail and white sea bass in inshore areas. It also includes halibut, kelp bass and sheephead. On the east coast it includes stripers, sheepshead, drum, sea trout, tautog, spanish mackeral, king mackeral and bar jacks. Also amberjack, crevalle, grouper, pompano, etc. All of these can be landed by a freediver with a reel equipped Biller speargun.
Tomorrow, I will attach drawings of the sliptip. The spearhead shown in the above photo is an example of engineering art. Some jugheads will assume it is akin to a railroad spike. Not. The pointy end is made from a slug of chromalloy (armor piercing bullet). The slug is press fitted into the 17-4 hardened stainless body and shaped on a lathe. The bore of the spearhead is cone shaped using a special tapered drill or reamer The specific depth and angle of taper are carefully controlled. The line hole is shielded by a shoulder ground into the body. This shoulder protects the line from shearing off by bone fragments. The line is looped to reduce tearing effect on the fish. Also, there is a reversal ring which is trapped by a knot or ferrule. This means that the fish can be removed and strung quickly setting up the next shot. Riffe and Biller sliptips are one shot deals and not practical for the average hunter. Biller uses a ring but it is not trapped, and useless. Moreover, the 1/16 cable will tear flesh. The coated cable is better but does not cling to the shaft if it is looped. So, Riffe has designed his for one purpose, that is the ultimate streamlining without regard to practicality for any but trophy hunters who call it a day when they spear one or two fish, even if it takes a week to do so.

It is not necessary to use a chromalloy tip for your sliptip spearhead. Moreover, the drawings I present will show how it is possible to make a reliable spearhead with a straight bore. There is no need to drill a tapered bore. However, I do recommend that your spearhead be made from 17-4 steel which can be heat treated later.

Here are some sketches
of a sliptip with straight
bore. Note the small hole
drilled into the cavity. This
prevents suction which could
hold the spearhead fast
resulting in a lost fish.
There is one error I spotted.
The slit which is to be cut
into the billet is rotated out
of place. It should be 3/4 inch
deep and cut into a flat which
is 90 deg out from the line


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I have heard the opinion that sliptips should 'wobble' to ensure quick detachment. With this head only minimum wobble should be allowed, barely perceptible. It should, however, not bind on the shaft. Make sure it will detach smoothly without binding on a rough spot. The material used is 3/8 hex, 17-4 ph. The tether can be 1000# kevlar or even soft 1/8 nylon although the line hole may have to be enlarged. Wally used tuna line and crimps which I also do. It is important to select the right capture ring, large enough to hold the point and reverse through the fish, but small enough to be stopped by the knot or crimped ferrule in the loop. Make the tether long enough so that, when hunting, the excess line can be pulled under the gun rubbers thereby preventing the sliptip from falling off.

Edit: 8/12/04; The clearance between the sliptip and the shaft or adapter should be 0.002 - .003. If the shaft is 0.313 it should be ground or sanded to 0.310. Use your best judgement as to looseness, tilt and ease of removal.
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In pic #1 one might notice that the grip looks different from the factory style. I cut away the 'bazooka' style guard which looks butt ugly to me. I asked Fred why he confused the clean lines of the original gun. He said that the hand guard reinforces the structure which supports the line release. Whatever. However, I did leave a small bridge of plastic to help hold it together, if that is in fact what it does in the first place. Never had any problem so far, knock, knock.
Odds and ends:
I've noticed that a late model Biller in my care has a stronger spring which results in a harder trigger pull. It is smooth enough, though, and is about the same pull weight as the Riffe Island and all Riffe mid grip. I suspect it's a liability thing with Biller. Even firearms are now delivered with very strong springs, probably for that reason. As I said earlier, some Billers, especially the first production mods of the new grip/sear from about 1994-5, show friction between the trigger and the line release. Don't run the shooting line too tight and it won't be noticed (much). I've tried filing and sanding the lower arm of the trigger to reduce this friction but it is hit or miss. The smoother the finish the better. On the plus side, the new style, with the bazooka grip, are made of stronger and thicker stuff than the Australian Sea Hornet parts which Biller once sold. Also, the Biller barrels are about an 1/8 thicker. The lockup between wood and plastic is much stronger making it safer to load up longer guns like the 54.
Why the tab?

Someday, the question may come up as to the purpose or function of the flight tab. Basically, this is an anti recoil device. No, it is not a 'dead mule' such as used on shot guns. I am referring to muzzle lift which occurs on big guns. A gun equipped with maximum rubber, which has an effective range of 20 ft, requires no hold over at all if the arrow has the tab. The teak 54 Biller, when loaded with two 5/8 bands of 150 pounds each, does not need the flight tab. There is not significant drop out to 15 feet, the max range. However, I do recommend that this be added nonetheless, even if only for a more reliable ring stop and longer rubber stretch. When the teak gun is loaded with three 9/16 rubbers of 120 pounds each there is some minor barrel lift which may cause the 5/16 spear to veer slightly, about 1-2 inches of drop from its normal trajectory on a long shot. This effect is totally counteracted by the tab which steers the arrow into its correct flight path. The effect is immediate and was carefully measured by Prodanovich on his own guns. Jack spent many hours in his friend's swimming pool testing his theories and this tab concept is rock solid. While I'm on the subject, the other factor in gun stability is weight, something that physicists refer to as inertial mass. The teak gun is heavier, stiffer and has more inertia than mahogany. You get the picture. The teak gun will shoot straighter. As long as the hardened stainless 5/16 arrow has the tab there is absolutely no need for any 'rail' , weights, stabilizers or other add ons.
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