I had this key ring that had a set of Allen wrenches on it, held in springs that fit around their long ends. The end coil of the springs were bent at 90 degrees from the rest and threaded on the key ring. One of those springs ( They were tension springs that had no space between coils.) was just a little too big to fit in a long .22 caliber plastic drop tube, that fits my Harrell measure. I grabbed both ends of the spring with pliers and pulled it till it was about as stretched as I could manage, and then trimmed up the ends, so that they would not hang up or when inserting it in the tube, or catch powder too much. At that point I discovered that the OD of the stretched spring was smaller than that of the tube, so I put a slight bend in the center of the spring, to cause interference that would keep it in place. After I put it in the tube, I positioned it far enough down so that if powder hung up in the tube above it, that I could see it. When you use one, it allows you to get the same advantages of a long tube with a very slow, or intermittent drop, with less trouble, BUT after the powder is mostly in the case, you need to tap the tube sharply, a couple of times to dislodge any kernels that have hung up on the spring, lest your next charge be a hot one. You can't get as much in with a long drop tube, as with a long tube, combined with a very slow drop or a long tube with one of these modifications.