Oops... Guess that explains the FTE's

[Dietz]

All AR bolts will break in the same fashion after enough rounds are fired. It's either going to puke a lug out or it's going to break in half at the cam pin area.


FA bolts don't exist.

FA carriers do exist, and bolt longevity varies according to manufacturing and component quality and engineering... and use.

 

[RickR1100]

I'm wondering if there is excessive gas going to the action... causing higher bolt velocities... and putting unwanted additional stress on the extractor function?

The gas port may be too large for that length of barrel... too much gas, higher bolt carrier velocity, causing stresses that are beyond design specs.

What buffer was being used? As we know, some are much heavier than others, beneficial in FA's.

What about the barrel? Specifically the chamber: was it truly milspec... or a civie "match grade" chamber that is possibly too tight for reliable and smooth extraction when it gets really hot? Remember, a chamber that gets hot, "tightens" onto the case. A tight match grade chamber will grip too hard if it gets very hot, better for a military chamber.

 

[Dietz]

I'm wondering if there is excessive gas going to the action... causing higher bolt velocities... and putting unwanted additional stress on the extractor function?

The gas port may be too large for that length of barrel... too much gas, higher bolt carrier velocity, causing stresses that are beyond design specs.

What buffer was being used? As we know, some are much heavier than others, beneficial in FA's.

What about the barrel? Specifically the chamber: was it truly milspec... or a civie "match grade" chamber that is possibly too tight for reliable and smooth extraction when it gets really hot? Remember, a chamber that gets hot, "tightens" onto the case. A tight match grade chamber will grip too hard if it gets very hot, better for a military chamber.

50k for a bolt that was run hard is pretty damn fine if you ask me.

The gas port will get larger and larger and gas pressure will get higher and higher when you get into the tens of thousands of rounds, especially under rapid fire. The only thing that can prevent this is an adjustable gas block, but even then by 50k the barrel must be shot out and the bolt could/should have given up a long time ago.

AR bolts could last a heck of alot longer if it wasn't for the unnecessary destructive testing every bolt must go through in order to meet the old TDP spec. It's one of the reasons KAC doesn't high pressure test their bolts. It basically cuts the bolt's lifetime in half, and the reject ratio has been a steady 0% for a good long while so they figured out why the #### should we do this anyway? It doesn't make any sense after they pass all the other non-destructive testings.