open muzzle vs. closed muzzle

[soljah]

okay, so first of all. what is the difference between an open and closed muzzle? why is there such a price difference? and what do they do to accuracy and power? and what is bulk rubber stuff? is it just buying rubber in bulk? like by the foot. and if so, how do you put it on your gun? sorry about all of the questions. i am kind of new to the speargun thing. thanks!

[spaghetti]

Open muzzle just gives you a cleaner aiming line, cause you have a visual perception of the shaft in all its length with no interruption. For this reason, some people say that open muzzles give guns a higher accuracy. Is it true? bah...Me I think it's just a fashion thing: newest guns are almost all with open muzzle, and this is why they are more expensive (new models have higher prices than "outfashioned" ones).
Me I've always used closed muzzles and feel no problem with accuracy. On the contrary, closed muzzle guns are faster and easier to load: unlike open muzzles, they dont' require to wrap up the shaft with the line.
--bulk rubber: you buy rubbers and cut them in the required size, instead of buying them ready made. It's a thing you can do to create your own custom circular bands, making a do-it-yourself wishbone with knots of dyneema or kevlar line. This way you save some bucks...

[strangelove]

I agree with everything that spaghetti but I would add that open muzzle will give you more power.

[Dan Man]

How is a closed muzzle going to give you more power

[strangelove]

The Open Muzzle gives you more power then the closed muzzle, in fact I was playing around in a poll with my friend. My with with my teak-sea azimuth 100 rigged with a single 19 mm (circular band) him with his Omer Master America 115 with the original omer band. Both using the same shaft, my gun had a longer shot then his.

[poacher]

Open muzzle -more power? maybe a little if spear is hitting closed muzzle due to some bending may have a little friction? testeing 2 different guns with different rubbers is not an accurate comparison of muzzle styles you would need exactly the same gun with only the muzzle different to be conclusive and then try over a number of shots and swap rubbers one rubber may have more elasticity than another from same manufacturere due to age,manufacturing variation and many other variables. closed muzzle faster to load ? I find open easier to get spear into mech without having to thread it through the small ring at end of muzzle just drop it on to barrel and push back last 50mm or 2" single wrap of line is almost automatic without concious effort after some practice your hand swings line around pin and end of gun then slide back to hook on line release in one fluid movement unless its tangled which happens also with closed muzzle, I have both but prefer open muzzle -only problem is in dumping surf it may come loose and line come off . this is not very common except in breaking surf.
Peter

[Dan Man]

I agree that is a very dodgy test...thats like me saying my riffe bluewater has more power than my rob allen because it has an open muzzle

[jon penrith]

I have open & closed muzzled guns.I think the test result is down to the fact that the master america has a standard euro rubber that pulls in line with the shaft.A circular one can also be added.The Azimuth uses circular rubbers only so you obviously have the extra rubber that comes around the front of the muzzle.Quality of the rubbers as well as thickness & thickness of shaft plus shooting line type all come into it.
I find that the open muzzle design has an annoying habit of the line coming off in surf or when its in the boat resulting in tangles.I also find it quicker to reload with the closed.This is a definite bonus when you are dropping on a shoal of fish & hope to string a few more before they move on.I dont find this so much a problem in the med where I tend to take fewer shots & have longer(generally )between dives due to deep diving.
Where open mules score over closed is when using shark fin loading tabs on spears instead of notched as there is nothing for the tabs to catch on.

[Dobs]

There is a huge difference between closed and open muzzle as regards recoil. Closed muzzles with screw-in bands tend to go up in the moment of firing causing inaccurate shots. Eventually the mind gets used to it and fixes the errors of the gun, but according to physics open muzzle should be more accurate.
I agree on the extra power part too. It is due to the extra piece of rubber passing through the hole.
Here is some info on the recoil and on closed vs. open muzzles
http://www.dapiran.it/dapiran/tecnic...tm#TERZA_PARTE

Sorry if you don't speak Italian, but the article has some very good graphics, so you can get the idea. There are loads of other sources also in Italian, but I think Dapiran is good enough expert, so I choose to trust him

[strangelove]

Sorry I should have sent both guns to Nasa to have the test done, spearfishing is such a precise science ! But my intent was to say the circular band adds power not the open muzzle, the master America has an Open Muzzle but with a split band. What was surprising to me was the amount of power that you gain by using a circular band. I also agree with the open muzzle being a pain on the boat.

[spaghetti]

Circular bands probably give more power than screw-in euro bands, but in many models they require a rail to be accurate, and the rail gives a bit of drag so that power diminishes...so what?
However, open muzzles do not necessarily use circular bands: the new Omer XXV shoots with open muzzle and couple of screw-in bands, same as Seatec gabbiano open and others to mention, while the sporasub instinct has a semi-open muzzle. They're "cleaner" to aim, but power is a different issue AFAIK.
---Curiosity: here in Italy the kind of muzzle with two or more holes for circular bands is called "australian". Is it really an invention of the aussies as you guys know?

[cadiver]

I'd like to chime in here too and ask a follow up (albeit maybe a stupid) question: is an enclosed track gun concidered an open mussel or closed mussel gun? Also what are the benefits for an enclosed track gun. I'm new to this whole spearfishing thing too and I really enjoy the threads I've read here. Thanks to all of you that have been sharing you knowledge for us rookies.

[strangelove]

cadiver

You find enclosed normally in wooden guns, the function is the hold the shaft in track while the rubber is in action to try improve precision. I've only see enclosed tracks on Wooden gun or the riffe metal tech, those have open muzzle and circular bands. I picture have a 1000 words.

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[jon penrith]

What are Omer thinking of with the xxv? If your gonna have an open muzzle for better sighting why use rubbers that pull in line instead of circulars??
Interestingly Fabrizio of Totem sub guns did some tests & found that rubbers which are split/screw in still caused the spear to wobble as the spaer passes out of the trigger mech & over the guide in the middle before passing out of the muzzle.With circular bands & a rail the rubbers keep the spear on the rail & this doesnt happen.
As for the rail slowing the spear down,Rob Allen says that the spear travells on a film of water which acts as a lubricant.Either way i cant see it has a massive effect.

[strangelove]

Jon

I have to agree with you, I love the excalibur 3000 but xxv I am not so sure.