A pretty sweet "G"

[RattleAkAk]

After market was all over the map for at least 10 years with dimensional variances on “Grendel” bolts.

Differences on the original and improved AA bolts relative to a standard 5.56 bolt are:

.136” recessed bolt face
2.810” OAL to set the firing pin back so you don’t have excess firing pin protrusion with Mil-Std firing pins
Extractor pocket depth is different
Extractor pin location is different to mitigate extractor binding inside the barrel extension
Extractor engineered specifically to work with 6.5 Grendel case head and rim dimensions with a strong lip
Tiny radiuses were optimized to increase bolt lug root strength.
Materials and processes were tightly controlled to ensure tough bolts.

In the after-market, we saw:
Cheap 8620 heat-treated improperly for some of the original low-costs parts companies (Model 1 Sales as an example)
.125” face depth
Thin-lipped extractors that failed quickly, lips ripped off
5.56-based extractor shelf dimensions
5.6-based extractor pin locations

Then we saw:
Correct .136” face depth
2.800” COL requiring specific shorter firing pin
Varying types of extractor shelf locations
Varying extractor pin locations
Varying materials and processes

Bill tried his best to get ahead of this by licensing actual Grendel bolts out to companies so that everything would stay standardized based on his years of testing and experience with the .50 Beowulf and initial 6.5 Grendel work, but too many in the industry assumed they could do it better, totally overlooking all the RDT&E he had done.

Same with chambers. He spent $11,500 on different reamer configurations trying to find a set-up that would shoot both 123gr Scenar and 90gr TNT accurately and almost gave up until testing the compound throat.

Aftermarket: “That guy doesn’t know what he’s doing. We can figger it out more better.”

It’s been interesting to watch.

The whole “Grendel II” chamber and bolts is a funny moniker to see all the time. No such animal exists, and yet “that’s the standard now”.

Thank you for sharing your knowledge!! With that said, and in the spirit of info sharing, not to ruffle feathers, do you agree with myrifle regarding Monster bolts being the very best out there currently?