JP upper + Factory Ammo= overpressure?

The marks you'd be looking for if it's jamming would be all the way around the bullet, one mark for every land of the rifling. They will start where the bullet almost reaches full diameter. I think the 2 scratches you see are probably from feeding.

Also if it's jammed very much extraction of a live round will be somewhat to very difficult.
 
Originally Posted By: Suppressed in SDI appreciate the information. I know very little about bullet seating and the like. Thus my reliance on factory ammo. The more I read about this the more I think that my bullets are jammed into the lands. When I charge a live round and then remove it, on close inspection there are 2 very light curving scratches on the lead. I assume this is from the lands. Would this ammo be salvageable if I seated the bullets deeper? Or should I ream the throat a little?

As 204 said... the marks you see are NOT from the bullet jamming - whatever problems you have they are not going away with a simple fix - there is something really wrong.


 
A little update. Found some federal fusion 120g and have shot 50 or so without problems. They have a much different shape than the Sierra gamekings, the ogive is further back on the bullet. Upon better inspection a round that has been chambered has a scratch/scuff mark about at the ogive that goes most of the way around the bullet. My gunsmith seems to think it's from being jammed into the lands. I'll post some pics but I'm not sure my camera is able to show the minute detail needed.
 
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A17BB9DC-1C10-486F-8D82-34479B09E9AB.jpg

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The first pic is the Sierra Gameking. It's kinda hard to see the scuffs. The next two are federal fusion. I think it's the same bullet and I believe I chambered that round twice. So what do you think?
 
Take a candle and soot a few different types of bullets and chamber them. You will know right away if the bullet is touching the lands. You will see individual marks around the bullet. The pics you posted look like its from the feeding process as they are stripped from the mag.
 
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