Full disclosure, this post is not about necking down for the purpose of seating smaller bullets. It is a DIY mod (hack) for a powder funnel.
DO NOT ATTEMPT THIS FOR RELOADING AMMUNITION!
This is a long story about solving a trivial problem by making due with whatever I had on hand. And… Maybe a little bit of a rant from the reloading bench.
The problem. Powder funnel neck not correct size for cartridge, and when jamming case neck up into the Lee’s powder chute, loss of up to .3gr occurs.
During a recent session of reloading some 223, I was having a devil of a time dialing in precise powder charges. It seemed the scale and measure were having a competition to see which would make me go bonkers first. The scale was drifting and the powder measure was bridging powder on the case neck rim.
Without a funnel to ensure ALL the powder went into the case, I turned to zeroing the scale on each case, jam case mouth up in the powder measure, drop charge, weigh case. Then, +.02 over, dump like 8 minuscule granules of powder, reweigh, no change, dump a few more granules, and then viola! -1 from target weight 
I’d throw a charge, weigh it and it comes up light, okay, trickle a few more granules… drop drop drop no change drop BAM +.03. (sigh) remove half of the trickled amount, BAM, -.02…01…0…-1. ARGH!
I solved the scale drifting problem by switching from AC adapter to four fresh new batteries. Apparently the wire nest and cheap AC adapter under my desk was part of the problem.
Press the easy button? No, not yet.
Between spilled powder and a drifting scale, getting a precise measure was exhausting. I only get hyper precise when working up a new load. This time around I was loading 40 cases for 4 different charges.
The Lee Auto Bench Drum usually works great with spherical or flattened spherical when dropping into the pan, but jamming the 223 case mouth up into the discharge chute was not working. Every throw had some spillage. Anywhere from .01 to .03 off and usually light, that is, unless the scale decided it was heavier.
Now, to tackle the spillage issue.
Even though the Lee “Universal” 22-44 Cal funnel is marked 22, do NOT expect to be able to use it for 223 Rem. The case neck just pokes through, right up to the shoulder. It worked great for my 308 and 30-06 loads, but useless for 223.
I was about to pull the trigger on a Lyman funnel kit when I had a spark of genius. Just make my own (duh). Without a machine shop, I had to get creative. Not that I’d know my way around a machine shop.
The bright idea was to neck a cartridge down to a little under the inside diameter of a resized case. Then cut off the case head and flare it out until the OD was a hair under the funnel’s ID.
It works like a charm now, but mistakes were made. They will remain largely undocumented. 
I chucked a case, rear end first, and inserted a drill bit for a mandrel. I tried regular pliers and a wrench first, didn’t do much except chew up the neck. So I dug through my rarely used tools toolbox and VIOLA, there she is. A non grippy hand tool tool with an arbor and die made just for this day.
I learned this method is known as rotary swaging. The electricians pliers could not be better suited. It cradled and captured the neck without it jumping out of the notch. It took several passes but it worked like a charm.
Now, to cut the case head off. Well, all I’m going to say is this. It is not my fault the Frankford Arsenal universal case trimmer looks a LOT like a lathe chuck. Some of you may recognized the advanced cutting tool I used.
Now for a precision flange with another precision tool.
Wrapped some masking tape around the case body until it fit snugly in the Lee funnel, then trimmed off a bit for a flush fit. Deburred with 800 grit sandpaper.
Now the funnel adapter fits like a glove, no more spillage.
Well, that’s the end of the story… Ehh, maybe not the END end, I need to raise my powder measure mount height because I cant get the funnel and a case under it. For now, I am happy dropping powder in the pan, weighing and dumping into the case with negligible to no powder loss.