[m91dragoon]

I've shot this ammo before with no problems. This last time out, 5 out of 20 had bulgeing primers. The rest of the brass looks good and groups as well as the other rounds. The brass is new and not reloaded. What is causeing this?

 

[Cheap_shot]

The protruding primers are caused by low chamber pressures that are too low to seat the case head back against the bolt face. The amount of protrusion is the difference between the cartridge and chamber dimensions.

 

[CW]

So these were underloaded? Who makes this ammo?

 

[m91dragoon]

The brass is Yugo and imported by Graf. I bought the ammo from mrnambu on gunbroker. I don't know if he loaded it or not. I've been very happy with the ammo 6.5 jap and 7.7 jap. from him. Clean and accurate 1.25" at 100yds with the 6.5.

 

[Merle1948]

The protruding primers are caused by low chamber pressures that are too low to seat the case head back against the bolt face. The amount of protrusion is the difference between the cartridge and chamber dimensions.

Second that.

I have the same problem with Hornady factory ammo.
I'm sure it's a liability thing, and pressures are delibereately held low, such as with 8x57 ammo.
It's not a problem with handloads approaching Japanese service / factory ammo pressures.