There's a few different methods used and it would also depend if you want to use a keel at all. My puddler I lean towards only using pad weights. With that way I use rubber bands to test different pad weights on the bird in a tub of water. With keels, hollow out the keel with a forster bit or mortice machine and either drop in lead pieces or use lead bird shot. This is one video on the tube that shows a keel weighting method. -
https://youtu.be/SSYWmrii2tM It can also get fairly intricate if your making a show bird, but it's not so with a gunner, no-show bird.
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