On the walls or the lip of the case?
Lip
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On the walls or the lip of the case?
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One fix if it is option 2 is just a stronger extractor spring but sounds undergassed. Bolt is likely not making full rearward cycle.
The feed ramps are likely a secondary issue and separate from the short stroke
The first time I ran my Radical Firearms upper and bolt, I had failures to extract during the first 20 rounds. After that, it started running perfectly.
I believe it had to do with the extractor and bolt breaking in. Now don't know if that's a possibility, but it's the only think I can of. Lube it up and keep at it. Of course verify everything is assembled correctly, but I believe you need to "break" it in.
I want to check out the gas port on the barrel and the gas port on the gas block. The gas block could be pushed too far back on to the barrel not allowing all of the gas to enter the gas tube thus providing not enough gas pressure. That is why I did not dimple the barrel when I tightened the gas block down. Just a little trial and error because these parts have never been used by us. I am proud of you for not throwing the rifle in the woods though.
Sorry to hear your AK-15 is giving you issues man...
I know you have put a lot of time, thought, and effort in your item. Hope it's a simple fix!