The only thing I would use a Pistol-Length Gas System with 6.5 Grendel would be subsonic loads shooting 140-160gr bullets.
Supersonic loads are hitting a Pistol Gas port location with insane amounts of pressure, that has to go somewhere.
The torsional loads being placed on the extractor are beyond the design window of the AR15 if you have a ~30gr case volume at 45,000-50,000psi chamber pressure pushing long, high SD projectiles through a tight 6.5mm bore.
When the case is obturated, not only are the case walls firmly attached to the chamber walls, but the case head is firmly seated against the bolt face, and extractor shelf with pressure.
As the gas flows into the Stoner expansion chamber inside the carrier/bolt combination and forces the carrier rearward before the case is able to rebound off the chamber walls, the bolt starts rotating in this condition of everything pressured up against the bolt and extractor.
The extractor is being asked to do a job it was never meant to do, with torsional loads (rotational axis) being placed on it, in addition to excessive longitudinal loads as it tries to rip the obturated case from the chamber.
This is worse than a large-ported 18" MLGS because of the Pistol gas port location.
Supersonic loads are hitting a Pistol Gas port location with insane amounts of pressure, that has to go somewhere.
The torsional loads being placed on the extractor are beyond the design window of the AR15 if you have a ~30gr case volume at 45,000-50,000psi chamber pressure pushing long, high SD projectiles through a tight 6.5mm bore.
When the case is obturated, not only are the case walls firmly attached to the chamber walls, but the case head is firmly seated against the bolt face, and extractor shelf with pressure.
As the gas flows into the Stoner expansion chamber inside the carrier/bolt combination and forces the carrier rearward before the case is able to rebound off the chamber walls, the bolt starts rotating in this condition of everything pressured up against the bolt and extractor.
The extractor is being asked to do a job it was never meant to do, with torsional loads (rotational axis) being placed on it, in addition to excessive longitudinal loads as it tries to rip the obturated case from the chamber.
This is worse than a large-ported 18" MLGS because of the Pistol gas port location.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com