it,s for strength when you cast out m8.
rule is 10lb of line for every oz of lead used.
shock leader is used so you can compress the rod in the cast and the line don,t snap.
i:e 5 .0Z lead requires 50lb shock leader.
without leader if you give the rod a good wack the 18lb will snap.
hope this helps
An up and down your rod + 10 turns on your reel (28ft approx) of Greased Weasel tied with a 4 turn grinner with a blob of super glue on the short tag end of the Weasel is an excellent shock leader. The blob of super glue on the end stops the tag end from hitting the rod rings.
A way of avoiding a tag end is to burn the end of the Greased Weasel with a lighter forming a blob, then tie a 4 turn grinner on the Greased Weasel with the main line, using the blob to stop it from coming off. This is the neatest way of tying a main line to a shockleader.
Although I mainly charter fish I always have a shockleader between my braid and end tackle. This is tied using the heated end method and I have never had any trouble with it. I landed my Conger using this method.
Tapered shockleaders are gimmicky and expensive, they are just another way of filling someones pockets.
Youv'e got me by the short and curlies here having to explain in writing, but here goes. (if you dont understand PM your phone number and I'll explain.
First and foremost you must use Greased Weasel shockleader, it wont work as well on others.
Using a lighter or match, close to but not on the end of the "shock", heat it up until a little mushroom appears. Remove heat. Then using your mainline, tie a four turn DOUBLE GRINNER onto the shockleader. By using a double grinner it leaves the tag end of the mainline parrallel with the shockleader. Moisten the knot on the mainline and pull it up tight to the mushroom on the shockleader. Trim the tag end and put a little blob of super glue on both sides of the knot , this seals it and leaves nice round ends to the knot that does'nt snag the rings. It is the neatest way of joining a mainline to a shockleader.
Wow, I hope I got that right and that you understand, if you have a problem let me know. I am sure that your local tackle dealer will show you how.
No doubt someone one will come back and tell us that it is useless, but I can assure you that I have been using this method for a number of years now and never has the mainline and shockleader come apart .