Rainier Arms should be out with their non FA upper in about 4-6 weeks. I am guessing it might save you around 2oz. You could also remove the FA internal parts and use the delrin plug which is available to save a little.
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Its better to have something and not need it than to need something and not have it..
On the other hand, I use mine all the time, to make sure the round seats after a press check.