Need Help Identifying a Mystery Fly Line

A couple of years ago I bought a number of fly lines on closeout for $1.47 each thinking they would be ideal for practice casting in the back yard. The lines were out of the box but on the spool and when I pulled the line off the spool I discovered that all the floating lines were a Fenwick product (and cast quite nicely for that matter) but the sinking line had no identifying label at all.

My Question: Not having access to a scale that measures in grains, if I were to rig up a simple balance scale with the first 30’ of the sinking line on one side and the first 30’ (less taper) of a WF or DT floating line on the other side would it come close to balancing when I finally tried the right weight floating line? I have floating lines from 2-10wt to try?

I think a penny weighs about 48 grains. 30’ of 6 wt line weighs 160 grains or about 3 1/3 pennies. See below for weight of 30 foot lengths.
AFTMA # Weight
(Grains) Tolerance
4 120 114-126
5 140 134-146
6 160 152-168
7 185 177-193
8 210 202-218
9 240 230-250
10 280 270-290
11 330 318-342
12 380 368-392

BH; As you can see from the chart Bobinmich posted, there is quite a large tolerance for each weight. So if you know a Duck shooter who loads their own shot cartridges. Ask him or her to weigh the line for you.
Hope you have fun and solve your wee problem. Jax

BH,

The method you are suggesting will get you close enough.

After that, it’s a simple matter to try a rod at/above/below and see how it casts.

Maybe even a ‘reason’ for a trip to the lake/river?

Once you are close, it’s really not all that critical.

Good Luck!

Buddy