Odd day shooting

[woodenword]

Odd day shooting on Tuesday. 2 uppers were malfunctioning and this is what I found.
Also, are there any differences between a 5.56 extractor an a 7.62x39 extractor? Measuring I didn’t see any difference.

7.62x39 11.5 upper broken bolt

5.56 10.5 upper broken extractor pin

Don‘t know where the third piece went

 

[amphibian]

Link to my webpage: https://c3junkie.com/?page_id=185
I've broken plenty of 7.62x39 bolts over the years:

However, I haven't broken any in a long time as I think 1. I don't shoot as much 2. More competition these days has produced higher quality bolts 3. I tune my gas down and add mass to the carriers to increase the bolt lock time.
Regarding the extractors, in most cases yes they are different. I've heard there are some manufacturers that made bolts that take standard 5.56 extractors but I haven't seen them personally.
PSA has an enhanced extractor made by Toolcraft that is usually out of stock but is in stock right now.
https://palmettostatearmory.com/ks-47-tc-e-extractor.html

Regarding your broken extractor pin in your 5.56, maybe that upper is overgassed too.

 

[SecondAmend]

IIRC, the amount of metal available to accommodate 7.62x39 ammo in a bolt assembly that was designed for .223 Rem/5.56x45 ammo was considered on the low side of desirability. When I had a 7.62x39 AR upper the bolt never failed, but I did have a "hot load" steel cased round that crushed the buffer against the back of the buffer tube. After that, I only shot American made, brass cased ammo.

MHO, YMMV, etc. Be well.

 

[sweersa]

IIRC, the amount of metal available to accommodate 7.62x39 ammo in a bolt assembly that was designed for .223 Rem/5.56x45 ammo was considered on the low side of desirability.

I'm an AK guy at heart, and that would be my first thought. I stick with 5.56x45 in my ARs and 7.62x39 in my AKs.