65 Receiver Set with Polymer mags from PF (HOPEFULLY)

[LRRPF52]

Which group of entrepreneurs is working through this? Have they experienced any KB's or bolt / extension failures? I'm aware of some new wildcatting going on, with some very aggressive expectations. I've not heard of any setbacks, though.

Word I'm getting through back channels right now is unusual brass diameter stretching just above the web, which is exactly what you would expect. Chambers are egging out, as guys have been encouraged to throttle them to 60ksi no problem. It will all be buried, but I don't expect Kabooms, just case head separations when midway through the chamber, the diameter increases, and the extraction cycle does what it does under pressure. I doubt the extensions or bolts will fail. Chamber walls...that's the weakness. Run the hoop stress on a .136" chamber wall in the AR15 diameter tenon even at 55ksi and see what happens.

http://lassengunsmithing.com/html/CylinderStress.htm

Use the thick wall cylinder function on the right.
Inside diameter = inside of the chamber. Check the diagram for the chamber prints and enter that data.
Wall thickness = minimum od of the thread relief - ID /2
Chamber pressure = the working pressure you are using
Then hit calculate.
There's a reason the .458 SOCOM and .50 Beowulf have operating pressures in the mid-30ksi range, and it isn't because of the bolt.