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<blockquote data-quote="DasSieben" data-source="post: 2660456" data-attributes="member: 29823">I bought 2 identical SOTA arms 7.62x39 uppers.&nbsp; I bought them to shoot surplus steel cased ammo.&nbsp; 1st upper had issues jamming below the feeding ramp.&nbsp; I ground out the feeding ramp and have had no other issues with it.&nbsp; 2nd upper didn&#039;t look like it was machined as well...had to drimel a dimple for dust cover to close and gas block was crooked. I went ahead and ground out the feeding ramps, and haven&#039;t had any jamming issues but first time out it short stroked every single round.&nbsp; Here&#039;s what I looked at:-First I switched out a buffer spring and tube for lighter ones that I had on hand.&nbsp; It actually seemed to make a little difference...maybe only 70% failure instead of 100%.-I swapped out BCG with my functioning upper.&nbsp; Didn&#039;t change anything.-Removed gas block again...everything seems to aligned correctly now.I&#039;m not sure where to go from here, except maybe start cutting coils off buffer spring.&nbsp; Or call manufacture.&nbsp; In order to keep everything the same and figure out the issue, I&#039;m using the same ammo and the same lower with both uppers.&nbsp; It&#039;s an Aero lower with a Spikes parts kit.&nbsp; Does anybody have any ideas?&nbsp; Thanks in advance!</blockquote>

[QUOTE="DasSieben, post: 2660456, member: 29823"] I bought 2 identical SOTA arms 7.62x39 uppers. I bought them to shoot surplus steel cased ammo. 1st upper had issues jamming below the feeding ramp. I ground out the feeding ramp and have had no other issues with it. 2nd upper didn't look like it was machined as well...had to drimel a dimple for dust cover to close and gas block was crooked. I went ahead and ground out the feeding ramps, and haven't had any jamming issues but first time out it short stroked every single round. Here's what I looked at: -First I switched out a buffer spring and tube for lighter ones that I had on hand. It actually seemed to make a little difference...maybe only 70% failure instead of 100%. -I swapped out BCG with my functioning upper. Didn't change anything. -Removed gas block again...everything seems to aligned correctly now. I'm not sure where to go from here, except maybe start cutting coils off buffer spring. Or call manufacture. In order to keep everything the same and figure out the issue, I'm using the same ammo and the same lower with both uppers. It's an Aero lower with a Spikes parts kit. Does anybody have any ideas? Thanks in advance! [/QUOTE]

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