I have never seen the conversion you are talking about.
But all our conversions with heavyer barrels have been with Lothar Walther Barrelblanks with the polygon profile.
My personal luger shoot within 1" at 25 meters with leadbullets, and it shoots of course better with jacketed bullets of good quality.
The balance of a heavy barrel is totally different, i also find it much easyer to hit the target.
My results got extremely much higher when i switshed out my custom 1911 for my custom luger.
Regards HÃ?Â¥kan
http://www.vapensmedjan.com