Geissele Stressproof Bolt Assembly With Extractor

Geissele Stressproof Bolt Assembly with Extractor The Geissele Stressproof Bolt is made from Carpenter 158, however this is not your typical material spec'd by the US Government. Since Geissele wanted to take it to the next level, their engineers worked directly with the Carpenter Steel metallurgists in Reading PA, to produce a special heat of material known as Carpenter 158+. This material is cleaner with less impurities, ultimately making it stronger and more consistent. We did not stop there, we decided to forge the bolt. Using the same process used to produce upper and lower receivers, a forged bolt manipulates the grain structure of the metal and yields a bolt capable of 5 Mfg: Geissele Automatics