This is not meant to be another how do you trim your jacket thread but rather your observations on the effect of trimming has on a jacket when point forming.
I build my jackets out of 22lr jackets as do many here on the forum. Although I have built 55gn and heavier projectiles, I got into it to build 40 gn FBRN projectiles and these were and still are my main fodder.
These short stumpy projectiles required me to trim my jacket to .460" and as I did not have a pinch trim die I built a end mill set up in a drill press to trim the jackets square and to length.
This works a treat and takes about 5 seconds, but I thought it slow and laborious but made a very fine jacket.
I never had a folded tip with the 1E PF die or with the 6cal PF die that I now have with any jacket that was trimmed with the end mill. I did build 52 and heavier projectiles with success but tended to get a few folded tips with jackets that had not been trimmed but just derimmed. I then ventured into 17 cal and drew my jackets down and trimmed with the same set up again no folded tips and very accurate projectiles.
I then invested in a .224, ET-2 pinch trim die from D Corbin as I thought it would speed up the process. This has proved not the case as you still have to knock some of the waste jacket off by whatever means suits you and the cut edge is nowhere as neat as a machined one. I also believe that the pinch trimmed edges from this die have a lots flaws in them. As with every thing, I made a trial run of 100, 40gn FBOT, 1E projectiles and over 80 % of them had folded tips and had to be discarded as seconds. I have made thousands of these and so I am happy with my process, so I was very disappointed with this result. I am a firm believer that folded tips have a lot to do with flaws in the case mouth and not necessarily from poor annealing practices or poor dies.
I have also picked up a 17 cal draw / trim die. This works differently and trims the waste off beautifully and have not had any folded tips but I have not tested them over 4K yet, while the machined trimmed jackets have been tested, without failure.
Do any other swagers who trim jackets to suit their needs have this problem or have any thoughts on a better way.
I know BT Sniper is thinking of building a trimmer of some description and hopefully may chime in with his thoughts.
Billsshed