Short 19mm rubber on a 70cm gun

[Mark77]

Hi everyone,
I have an old Sea Hornet (Australian brand) rubber powered gun. It is only 70cm. The guns came standard with a screw in bridle and a thin (12mm?) rubber. The gun was given to me and it is in very good condition. The metal components seem to be of a surprisingly high quality and all are spotless. These guns came standard with a rather heavy 8mm stainless shaft. This is the biggest issue with the gun from what I can see as the standard rubber is not powerful enough to propel the spear with enough power.

I had some old bulk rubber (19mm) and decided to make up some rubbers for it with the rigid U shaped bridle with brass balls on the ends which is similar to the standard bridle design. The rubbers I made were 26.5cm lond not including the bridle. I have tried 3 times now but each time I try to load the gun, the rubber breaks half way along where it goes through the hole under the muzzle. Not sure if it my rubber or if this is a common problem with trying to make short rubbers out of thicker rubber tubing. The tension required to load the gun tells me that it will be quite powerful - not sure about accuracy though....
I have lengthened the shooting line accordingly.

The spear shaft does have 2 notches and the hole under the muzzle is elongated so that 2 rubbers could be used. Perhaps 2 x 16mm would be better....

Any advice on getting more power out of such a short gun in order to drive the heavy shaft at a decent speed??

Cheers,
Mark

 

[Pinniped72]

Your rubber is probably degraded, check the rubber hole in the muzzle for any sharp edges just in case. 19mm rubber is strong rubber and if it is not getting cut or nicked in the hole it wouldn't snap through loading if it wasn't degraded. Using short 19mm rubbers is not a problem but as you have found out, require effort to load. Two 16mm rubbers would be easier to load and an 8mm shaft should be able to handle it. One thing for sure, ditch the solid metal bridle/wishbone especially with the 19mm rubber, they can cause serious damage to your hands when they fail. Solid wishbones aren't generally used with rubber over 16mm and even then switch to dyneema, you will never go back. I have a 60cm Omer that I reduced from 110cm, it has a short 18mm rubber with dyneema wishbone and a 7mm spear, Love it. I did have two 14.5mm rubbers on it but for short guns I prefer the simplicity of a single stronger band. I am very delayed with this response so you have probably sorted it out already, anyway good luck with it!

 

[Apneaddict]

Alternatively, you can see if you can retrofit a roller muzzle onto the barrel, as a 70cm gun with a heavy shaft would be begging for more band pull and a roller can accelerate the shaft all the way to the muzzle, as opposed to maybe only 1/2 of the length with a traditional rubber configuration.


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