I did notice that DAA now sells a spring add-on for their feeders where originally there was no spring.....I'm thinking they copied the 3D printed ones too. The RCBS rifle bullet feeders do not come with return springs, but I've never seen two bullets fed. What I have experienced with the RCBS ones is forgetting to use enough care moving them around as to not come apart and lose ball bearings on the floor! The spring prevents that.....so I 3d printed a spring mod for them too.....see picture below:
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The RCBS ones work 100% without doubles or misses too. I hadn't heard that DAA's can drop doubles before Kalder's post. Even with their spring kit? I'm still not sure how the new Lee's work with their springs....just too hard to see from the pictures so far.....maybe a video is coming? Will be fun to try one.....will have to be patient until January.
Im just using a rubber band to pull the DAA die down to put some additional pressure on it right now. Im working on building a 3d printed part similar to DAA and yours to combat the issue. It only happens with 9mm bullets though. Never had an issue with rifle.