is this a pressure sign? and what makes flyers happen?

[bluebayou]

LOL 
If in doubt, I guess that the prudent thing is that it IS a pressure sign.
If you can see them there is a mark at about 6:00 on the two cases on the left and middle.  The one on the right case is about 4-5:00.

I loaded 27.0 grains of H4895 in the 7.62x39 with a 150 grain Hornady SP.  They look normal on the face of the case, but have the strange primer marks.  The ones in the picture were loaded to 27.5 grains and have some kind of ejector/bolt face mark on the case.  I was firing the new SKS. 

Handloading for a semiauto is pain in the butt.  I didn't think about having to find the brass.  I fired 20 shots and recovered only 12 pieces of brass.  I was trying to hunt for them whenever someone called "downrange".  It was raining......target holder broke in the truckbed on the way out.....what a mess.

My second question would be what makes flyers happen?  The SKS trigger is the weak link in my opinion.  I have a hard time with it.  All groups, 123 VMAX, 150 SP, Wolf MC, Golden Tiger, everything had 2 together and 1 high, or 4 together and 1 high. 

[beemanbeme]

There are several ways to determine pressure.  Often, if you only have one sign, with the absence of the others, the cause is something else.  The cases you're holding don't look like they've been motored too hard. The writing on the case head is still deep and plain and if that is a ejector mark it still doesn't look like the case head has been extruded into it.  While you have a ring around the firing pin dent, the primer itself is still nicely rounded.  I think what you have is a too big hole in the bolt face.
 

[Wingman26]

If you look at those primers that is a very mild load, the rounded appearance is a dead give away, the marks you are looking at are common on semi autos, it's related to the design of the ejection system, not high pressure.

This photo is of an extreme over pressure load, but this shows what a flattened primer really looks like, if they ever look like this....STOP!



Flyers happen, there are a million reasons why, most of the reasons are connected to the shooter, but the absolutely horrible trigger on an SKS doesn't lend itself to accuracy, for that matter, it's a mistake to use accuracy and SKS in the same sentence.  One writer talking about Russian rifles like the SKS and the AK series, said that they aren't measured in minute of angle, more like minute of football field!