One of my favorite flat bands are ordinary Alliance #107 rubber bands, available from most office supply stores in the US, though I buy mine from Amazon.com. They are cheap, require no tricky cutting and last a long time. Are they good enough for you? Good question, so I decided to do some tests to help you decide.
For comparison, I used two identical frames, my own design La Cholita in half inch plywood. One frame was banded with #107s and the other with .050 food grade latex from RubberSheetRoll.com cut the same width as the #107s. Both bandsets were fitted with Performance Catapult's (Jim Harris) pouches. I tied them on with thin strips of TB Gold in an OTT configuration and 8 inches between the pouch-tie point and the frame.
The first step was to fire 25 break-in rounds with each slingshot. I used .375 (9.4 mm) lead balls, and got a bit of hand-slap with both, indicating there is more energy available. Then I measured my draw-length at 34 inches, and using a digital fish scale measured the pull strength at 14.08 pounds for the #107s and 11.44 pounds for the latex.
Next I set up my speed test equipment, consisting of a metal chair with a wooden stick affixed to the back and a clothespin to hold a 5x8 inch index card located exactly 10 feet away from my catch box fabric. Then I placed my Acer Netbook on the chair and using Audacity, I recorded the sounds of a dozen or so shots from each slingshot hitting first the 5x8 card and then the cloth backstop 10 feet away. Then I transferred the files to my big computer and read the files to measure the elapsed time between the two strikes. I entered that information into a spreadsheet and calculated the speed in fps for each shot and finally got an average speed and energy. Here are the results.
Average for 10 shots = 173.87 fps, 5.03 lbs/ft energy
Average for 10 shots = 183.95 fps, 5.60 lbs/ft energy
So far, no surprises. I expected the latex to be faster, but was pleasantly surprised to find the #107s to be as fast as they are.
Next, I will shoot both slingshots until the bandsets wear out or break. Past experience tells me to expect about 300 shots from the latex and more from the #107s. Every shot is recorded, so for the first time I will have an accurate count.
Whichever breaks first will be replaced with a set of Tex's Field bands, and I will do the same speed, energy, and longevity tests on them, for comparison purposes. Note: Everyone already knows that Tex's bands are as good as it gets, so there really is no need for me to reinvent the wheel.
14 August, 2011 - The left side latex band broke at the pouch after 390 shots.
15 August, 2011 - 490 shots total on #107 bands. Very light scuffing at fork. No tears.
16 August, 2011 - 600 shots total on #107 bands. No tears.
17 August, 2011 - Velocity test - 178.7 fps 5.3 lb/ft energy
19 August, 2011 - Band broke at 696 shots