pneumatic vs band guns

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flspy

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Location
Boca Raton, Florida, United States
# of dives
100 - 199
I live in South Florida where the preference for band over pneumatic guns is probably 100 to 1.

When I first started diving back in the 1980's pneumatics were all the rage. Now they are relegated to a few communities of fanatical adherents.

With offerings from the likes of Mares and Cressi, clearly pneumatics are not produced by unknown off-brands.

Would love to know what pneumatic gun owners find so useful about them over band guns, and specific applications where they shine.

I know some people claim they are hard to load, and that the gun must be fired before returning to the surface- you can't just pull bands off.
 
Not a pneumatic owner here, though I've used both. Granted I haven't used a pneumatic in about 10 years. First speargun I've ever shot was a pneumatic, Mares Cyrano. It was my buddy's gun, and he swore by it over the band guns. I didn't particularly care for it. The method of loading seemed more dangerous, and there was an extra piece that could get lost, damaged which would effectively end the hunt. And as you said, only one way to unload it.

A few years later, his gun needed servicing as the pneumatic chamber was leaking. Not something he could do at home. He borrowed my band gun for a few trips, and may be close to converting.

Pneumatics also suffer from reduced power as you go deeper as the pneumatic chamber no longer has as much of a pressure change compared to the surrounding environment. As I understand, some gun makers may have come up with a way to mitigate this, but in the end it's physics. You may be able to do some things to minimize the loss of power, but you aren't going to solve for it completely.

There were not enough pros on the pneumatic side for me to justify when I bought my first gun. Really, I can only think of one. Less frequent maintenance. With a pneumatic I don't need to change bands every few months or more. However, since I can change bands on my Ocean Rhino in a matter of seconds, I don't see this as a really big mark in the pro column for the pneumatic.

Plenty of cons, though.
Depth is a factor.
With a band gun, it's easy to change power. I normally dive with two bands on the gun, but only load one. If more power is needed, I can load that second band. I can also vary the thickness and length of bands to adjust power.
IMO, it's easier to load bands than a pneumatic, plus I never need to put my hand over the business end of the gun. I can easily check that the shaft is locked in place before I begin loading. With a pneumatic, if I slip when loading, that shaft is likely firing.
Maintenance on a pneumatic gun is much more costly when needed. I can do a lot of the maintenance on my band guns myself.
Band guns are far less complicated, and much less proprietary. A band is a band, and a lot of shafts will work on a few different guns. There are a few release mechanisms out there that require a different shaft, though.
 
I can't disagree that pneumatics are (slightly) more complicated than band guns, but I also don't find them difficult to service. Most are built to the same design, if not actually in the same factory, from what I can tell. Once you've taken one apart, you can probably understand any other. In fact, I'd be surprised if a simple pneumatic has that many more parts than a band gun. It's about 95% about o-rings with pneumatic guns, occasionally a piston replacement (readily available online), though you can get scratches to the barrel surface (replacements are available for many, as well). Even at that, a slow leak requires repumping now and then, but doesn't always render the gun useless for the length of a dive. They come apart and go together pretty quickly. The few that I've had and used with any regularity haven't required service, or even pumping, over long periods.

I understand the theoretical concern about depth, but I have yet to notice a practical handicap, though I don't dive deep. Also, you can simply pump the gun to work best (up to the limit of your ability to load) at deeper depths, if that's what you need. I was surprised to learn that the working pressure of a pneumatic is 300psi or even greater. A change of 30 psi in external pressure doesn't seem a lot in that context, and I don't even know how that aspect of performance compares to the inertial resistance of accelerating the water and shaft out of the barrel, in the blink of an eye. It may be that 50 ft difference of depth is pretty minor in the overall physics calculation.

I find pneumatics of comparable length to have more power than band guns, when talking about shorter sizes, 18-27" barrels. It's also true you don't see many pneumatics longer than 100cm, and few even at that length. At some point, spanning the length of both gun and shaft to load becomes unworkable. I shoot mostly at short distances here, and often among and under rocks, where a long gun is unwieldy. I also find loading a pneumatic to be more controlled, and less painful. They are definitely faster to reload. Most pneumatics of any length have two power settings. With pneumatic shafts, there is some proprietary nature to the rear fitting that has to mate with the piston (and some overlap in fit among brands), and two main shaft diameters, but those rear fittings thread on, so the shafts themselves are pretty generic.

I've heard some say that pneumatics make more noise. Maybe that's true, but band guns are plenty noisy themselves. If you really need to reach out, though, I'd say a big band gun is the only choice.
 
Band powered guns offer a lot more tuneability. And, since I build my own guns, there is only one choice for me.
 
What's 'tuneability'? You can vary the power of a pneumatic infinitely within the bounds of the owners ability to load the gun. Do you mean something else?
 
I use a pneumatic over a band gun, having used both. One big difference is that out here on the NorCal coast is that the viz really cuts down on the length of the shot. On a close shot they are quite powerful and fast to reload once you get used to them. I could see a real problem with me reloading a pnumatic longer than the 2+ foot long gun I use. If I had better viz, I'd be looking at a band gun.


Bob
----------------
I may be old, but I'm not dead yet.
 
What's 'tuneability'? You can vary the power of a pneumatic infinitely within the bounds of the owners ability to load the gun. Do you mean something else?

I guess I'm not that familiar with pneumatic guns. Curious, how do you tune a gas-gun for more or less power? And, can you do it underwater?
 
You vary the final pressure when pumping it up. It's possible, but probably nobody does it, to release pressure underwater. The main adjustment is a two-position lever for full or partial pressure. It closes off a portion of the pressure reservoir so that as the piston moves down the barrel during the shot, the expanding internal volume has a bigger effect on lowering effective pressure behind the piston.

What do you do to tune the band guns? What is the objective?
 
I could use a sharp stick,a piece of volcanic glass,a Glock,a Purdey double or a pneumatic.

I choose to use a band gun as spearfishing is my primary livelihood.I'd use a pneumatic if I had too,I don't however.
 
You vary the final pressure when pumping it up. It's possible, but probably nobody does it, to release pressure underwater. The main adjustment is a two-position lever for full or partial pressure. It closes off a portion of the pressure reservoir so that as the piston moves down the barrel during the shot, the expanding internal volume has a bigger effect on lowering effective pressure behind the piston.

What do you do to tune the band guns? What is the objective?

I can vary the stretch length of the bands (of course this is done before getting in the water), but once in the water, I can choose how many bands I load on my spear shaft... short range hole-hunting (maybe one or two bands) or longer range open water hunting (four or five bands).
 
https://www.shearwater.com/products/perdix-ai/

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