The Great Gun Question

[miketsp]

Since this is a gun thread.
I haven't hunted in many years (early 70s) but I used to use a Nemrod pneumatic gun which had the great advantage that you could set the working pressure anywhere between tiddler & shark, it was originally bought for shark fishing in the Canary Isles.
The rubber banded guns at that time were not very powerful.
Nowadays most of the discussions I see refer to banded guns.

Is there a reason for this?
What are the pros and cons nowadays?
Have the rubber bands improved?

 

[DA Aquamaster]

Band guns have the potential for more power and for longer shafts.

With a pneumatic, shaft lenght is limited by your reach. The lenght of the shaft plus the lenght of the gun has to still be within your reach to cock it. The total power of the gun is also limited by the arm strenght of the individual diver.

With a band gun, shaft lenght is still limited by your reach but you cock the bands with the shaft in the gun so it is just part of the shaft lenght that must be considered. This allows much longer shafts and guns. Plus the total power of the gun can be developed by 2,3 or more bands, so the total power can be 2,3 or more times the power required to cock a single band.

And yes, in general the quality of production band guns is much higher on average than it used to be and mid level and high end guns are built much more substantially than in the past.

One of the traditional considerations was that pneumatics lost power with depth as the relative differences in pressure decreased while band guns tended to lose power the longer they were cocked. This is still true today but with the excess power available with a large band gun, the loss is acceptable.

 

[SpearSlinger1]

Well, Saintsfan, there are four lengths you want to look at on a band gun. The length of the stock, the length of the shaft track, the length of the shaft and the length of band stretch. These, along with the relaxed length and diameter of the bands and number of bands, should be able to give you at least a ballpark idea of the power and effective range of the gun.

When folks refer to a 48" gun some are refering to the length of the shaft, but I don't like to do it this way because the same gun will work with shafts of different lengths. Myself and some others like to refer to a gun by the length of the stock, but this isn't very good either. Some manufacturers leave quite a bit of stock unused in the rear section of a gun, while others use as much of the stock as possible to cut the shaft track, Riffe, Wong, Yokooji, Internet Customs, etc., making for a much more powerful gun in the same length package.

Feeling confused? Me too. :06:

DA Aquamaster hit it right on the head for the differences between a pneumatic gun and a band gun.

 

[miketsp]

Thanks for the answers. Just a couple of comments.

With a pneumatic, shaft length is limited by your reach. The length of the shaft plus the lenght of the gun has to still be within your reach to cock it.

With the model I had the pistol grip was mid gun so this was not really a limitation. To cock it you crossed your feet and put the pistol grip in the "V". With your hands over your head you could pull the long shaft efficiently.

The total power of the gun is also limited by the arm strength of the individual diver.

Fully agree - took a bit of working out to be able to cock at nearly full pressure. I never managed to load mine at full rated pressure.

One of the traditional considerations was that pneumatics lost power with depth as the relative differences in pressure decreased while band guns tended to lose power the longer they were cocked. This is still true today but with the excess power available with a large band gun, the loss is acceptable.

Well I never used mine below 20m (3ATA) & given that I generally used it charged somewhere between 20 - 30 ATM that didn't really affect me. I know some people go a lot deeper.

I also thought that the other advantage of the pneumatic gun is that the force applied to the spear is almost linear along the whole accelerating movement. The volume of the shaft tube is small compared to the total reservoir volume.

And as you say the big advantage is that you could be swimming for 2 or 3 hours with the gun cocked and it's always ready for use at a constant power.

 

[scubafool]

Man, am I ever so proud! A thread that I started has generated this much useful information! Seriously, everyone, many, many thanks for all of the help you have been to me so far. I never realized just how many different issues you could look at in something as supposedly simple as a speargun.

SS1, your last post, #13, is causing me to ask as many questions as it answered, so please bear with me. The following represents what I gathered from your post & what 10 minutes of thinking deduced from it.

Stock length- This basically tells us one thing, & that is how long the total gun is. Shorter guns are more maneuverable, while longer guns have the potential for more range & power.

Shaft track- Does this limit the shaft length that you are able to shoot from a gun? Doesn't this also limit band stretch length?

Shaft length- OK, now things start to get crazy in my coconut that I use for a brain. Longer shafts should equal heavier shafts should equal lower speed but more kinetic energy which should equal better penetration within it's effective range. Shorter shafts should equal lighter shafts should eqaul higher speeds which should equal longer range & better accuracy. And let's not even get into shaft diameter at this point. Whew!!

Bandstretch- Isn't this the biggie in determining the power of a gun? If you stretch a band out farther, it should have more stored energy, correct? While a 3 band gun with a shorter stretch might have more power than a 2 band gun with a longer stretch if you were to add a 3rd band to the gun with a longer stretch, I would think that you would end up with more power than the shorter gun. Then, of course, we could get into band lengths & thinckness, but the coconut is a-hurtin' already.

Thanks for everything!

 

[FredT]

Long shaft is accuracy related.
When the shot HAS to kill immediatly any gun is accurate to the length of the shaft. the error circle at that point will double between one length and 1.5 lengths. At 2 lengths you'd better be able to fight the fish 'cause killing it is starting to be luck, while a 3 shaft length shot is almost a "hail mary" attempt.

Power and penetration is shaft length related too, but accuracy is the driving force.

FT

 

[SpearSlinger1]

Phew! That's a lot of info. Okay, I'll give it a shot.

Stock length- This basically tells us one thing, & that is how long the total gun is. Shorter guns are more maneuverable, while longer guns have the potential for more range & power.

Right, but this is keeping in mind that just by the nature of the beast a rear handle gun is not going to be as maneuverable as a mid-handle. Now, there are mid-handles and then there are mid-handles and they're not the same thing. What I consider to be a true mid-handle uses as much of the stock as possible for the shaft track. These guns will have the grip and trigger located up the stock somewhere and some kind of push rod arrangement connected to the trigger that activates the release assembly in the rear of the stock. Some manufacturers locate the trigger and release assembly together up the stock and call it a mid-handle, but all that is, for all practical purposes, is a short rear handle with an extra long extension on the butt.

Shaft track- Does this limit the shaft length that you are able to shoot from a gun? Doesn't this also limit band stretch length?

Yes and yes. A longer shaft track will allow the use of a longer shaft without having too much overhang of shaft in front of the muzzle of the gun. It will also might allow for longer bands, but for sure more band stretch than a gun of the same overall length with a shorter shaft track.

Shaft length- OK, now things start to get crazy in my coconut that I use for a brain. Longer shafts should equal heavier shafts should equal lower speed but more kinetic energy which should equal better penetration within it's effective range. Shorter shafts should equal lighter shafts should eqaul higher speeds which should equal longer range & better accuracy. And let's not even get into shaft diameter at this point. Whew!!

Right, but only if the power of the bands is the same for both shaft lengths. I think there's more benefit to be gained from powering up a longer shaft than a shorter one. Be careful if you decide to power up a gun over what it came with stock. Too much band power applied will cause some trigger designs to become stiffer, or harder, to release, some will not release at all and some will simply come from together with an unexpected release of the shaft. I also think a longer shaft is inherently more accurate. This goes back to what FredT said about accuracy and shaft length, but I think some of that depends on how well tuned, or not, a particular gun is.

Bandstretch- Isn't this the biggie in determining the power of a gun? If you stretch a band out farther, it should have more stored energy, correct? While a 3 band gun with a shorter stretch might have more power than a 2 band gun with a longer stretch if you were to add a 3rd band to the gun with a longer stretch, I would think that you would end up with more power than the shorter gun. Then, of course, we could get into band lengths & thinckness, but the coconut is a-hurtin' already.

It can be if the bands being compared are the same diameter and material. The further a band is stretched, up to a point, the more energy it will have on release, but keep in mind that with a speargun it's not stretch and release. You'll be putting the band under tension and holding it in that state until you're ready to release the shaft. The further a band is stretched the faster it will lose elasticity resulting in a gun that loses power over time. Eventually, after you've used your gun a while, you'll want new bands. The next time you go in the water you'll notice, "WOW, what a difference." All band guns do this, it's just that with bands that are stretched further you'll be replacing them more often and after you buy a few you'll start thinking the guys that make something this simple must all be driving Ferrari's and Lambourgini's. After that you'll probably do what I did and learn to tie your own. Especially after you've realized that the one gun you have that is perfect for this really doesn't do that very well, but this other gun will, and that other gun for this other thing, etc.

P.S.-If you take the bands off your gun between trips and store them in the refrigerator crisper they'll last longer.

 

[pescador775]

Scubafool,
Forget the pneumatic gun. Its parts are machined to close tolerances and can be affected by salt and sand.

There are entirely different sight pictures and maneuvering techniques between rear grip and mid grip guns. Also, there is a big difference in the shooting techniques for a short mid grip and long mid grip. If I were you I would decide on a particular type of gun and stick with it. Switching between a mid grip and rear grip could produce some missed shots at the outset. I should say that the outset, that first shot, will probably be your best opportunity for the day but that varies with locale.

Look, you've been getting a lot of advice, much of it technical. There have also been a couple of good, practical comments. Here is your first advice from me. Do not buy an expensive Riffe gun, even if it is the "low" priced line, the competitor. These guns are for insiders only. The open muzzle is slow to load; the line follows a complicated pattern and the shaft may slip off before the load is complete; and the line release cannot be used with steel cable because it scars the wood which can lead to damage around the wood parts joining the line release. The line guide is iffy on some older models and the line will slip off before you're finished loading. The spear tips are quirky, expensive and have odd ball thread sizes.

There are two types of hunting, bottom and blue water, tanking and freediving. The choice of guns is related to this. Generally, a bottom gun should be a 'beater', a sturdy metal type that can be flooded or weighted to lie on the bottom when the shaft is released. For blue water, the wood gun offers advantages. However, this becomes a matter of complex factors and I can't go into it here. Basically, a teak gun has a high inertia and accuracy and is preferred for guns over 48" total stock length. Short wood guns should be mahogany. Otherwise, a short gun with reel won't float which causes real problems for the spearo. The shaft should not be larger than 5/16 except for monster guns. It should not project more than six inches beyond the barrel. Very long shafts flex during flight which causes problems with powerful guns and they are slower and difficult to handle. It presents maneuverability problems with short guns.

The Biller is a good all around gun. It's wood construction and good shooting accuracy make for confidence. The semi closed muzzle is outstanding for utility and accurate sighting. The various parts are plenty strong for most spearfishing and the gun can be picked up on E Bay for little money. Look for the type with enclosed grip because these models are made from stronger components than the old Australian type.

Check out the JBL for bottom fishing.

I am not aware of any reasonably priced and practical mid grip gun. The Riffe is an expensive, trick type gun intended for people like me who shoot 100-400 lb fish. I own several. I own several Billers also and prefer them for most hunting.

The old US Divers Sea Hunter was an adequate mid grip type for bottom hunting but had delicate plastic parts and a 3/8 shaft, much too slow. However, if you could find one cheap you should know that a 5/16 spring steel shaft will work in this gun. It must be hand made. Starting with a Biller shaft a person who is good with a file can modify it to fit the Sea Hunter. The sear grooves are crucial however. The angles have to be just right. If you decide to try a mid grip this might be an option.

It is a tradition among spearos to build or modify their equipment. If you get into spearfishing seriously, this will become part of the mystique and you will enter the tribe of underwater hunters mentally as well as physically.

 

[pescador775]

Scubafool,
Let me give you a guide for measuring the potential traction (power) of a gun and how it relates to length. This is the method used by pros. Measure the distance from the rear of the muzzle slot to the farthermost shaft groove (nearest to the butt).
24" small gun
36" medium gun
48" big gun
54" very big gun

The ultimate power will depend on the number, size and length of the rubber bands so that a mid power gun can be used in a low power situation (rocks) by unloading one or two bands.

Although a mid grip gun is preferred for maneuverability it is also harder to cock so it may be that the gun will have to be equipped with relatively long rubbers depending on the diver's strength. The rear grip with extended stock is harder to maneuver but offers more leverage allowing heavier rubbers, all else being equal.

Spear tips are very important. The type that you should be using is made of hardened steel with two wings. The tip should be detachable and held by a short length of cable. The tip should be the conical, hardened type, not the type with tricut or facets. The spearhead should feature a sliding ring on the haft. This is slipped over the wings allowing quick release from the fish. If you use a slip type it should have two flukes, not one. A single fluke will cause the shaft to dive. Some Biller heads are made like that, with single fluke. Use JBL detachable head if possible. Stay away from Riffe, they don't use the ring on their detachable heads, not any I've seen anyway.

Rubber bungees. called 'shock cords' are useless on big guns as they tend to recoil and wrap up the muzzle. They work OK on small guns. Their only purpose is to make it easier to string the gun by providing a bit of stretch when looping the line over the release.

Apply a drop of blue loctite to the shaft threads before screwing on the head.

 

[JustinW]

my LDS let me borrow a JBL 38 special NW. A nice little reefgun. I took it out on an ab dive and thought i would try to shoot a fish if i could find out. I speared my first fish opn saturday, it was pretty cool, i think i would enjoy it more on scuba though