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Hello all! This is my first post on this forum. I recently purchased a 20" Sanders Armory precision upper. I purchased it used with 100 rounds of Federal Fusion through the upper, and it's quite accurate (5/8" group at 100 yards). However when trying to extract live rounds I have to hold the charging handle while slamming the stock against the ground to get them out. Through a lot of experimentation, I've learned this only happens when the rounds are fed from a magazine. If a round jams, I will force it out, remove the magazine, and drop the round in the chamber. When I do that the round extracts with no issues. I've tried different magazines, different bolt carriers, and different ammunition. Im using this upper on an m&p15 lower. What i have noticed is when i have the 5.56 upper on and I put the 6.5 grendel magazine Into the rifle, the magazine seats easily. When the 6.5 upper is on the lower, I have to apply some force to get the magazine to seat. I'm hoping with all of this information the fine folks on this forum can help me solve my issue. Thank you all in advance for your help!
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First thoughts are out of spec ammo or short throated chamber? Have you tried taking the upper off, cleaning the chamber, and dropping a fresh (not previously chambered) round into the chamber? If you then orient the upper so the muzzle points up, the round should drop out without having to smack the upper on the bench/floor or use a pushrod.
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Yes I have tried dropping a fresh round in. The round slides right out without any hesitation. The two types of ammo I've tried are federal fusion and hornady black. They both fit in the chamber without issue. Only when I try to feed them through a magazine do the issues start
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Out of spec upper reciver. The 556 barreled upper and grendel mag seats fine.
Grendel upper the grendel mag is hard to seat.
You have a out of spec upper. It's dragging the bcg badly and making it somehow not fully seat and properly lock up. And your fighting the bolt lugs and barrel extention lugs too break free of each other and extract.
Pick you up a stripped upper of your choice and strip all the parts from the grendel upper and rebuild it with the new one.
Should fix the problem. Are call the place you bought it from and see if they will replace it.
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Is there any way for me to determine definitively that the upper reciever is out of spec? I'd hate to have to send the upper back and have Sanders Armory tell me everything is fine
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WickedInexperienced Wrote:Is there any way for me to determine definitively that the upper reciever is out of spec? I'd hate to have to send the upper back and have Sanders Armory tell me everything is fine
You already did that when you tryed the grendel mag with the 556 upper.
You could probably pull the bolt and try it in the bcg that is in your 556 upper and repeat the first test you did and see if it happens the same.
The surefire way would be to strip both uppers and rebuild the grendel on the upper that has the 556 barrel in it now. And install the 556 stuff in the upper that had the grendel barrel and then repeat the test you already did.
This is just me talking but if it was mine I would just order a stripped upper from a online dealer and rebuild the grendel upper with the new stripped upper.
I hate sending stuff back if there is a problem, I tend to just fix it myself, most times it's cheaper and quicker.
But to recap.
Grendel mag into grendel upper, mag very hard to seat and bad feeding and rifle jams up and you have to get physical with it to remove round.
Grendel mag into 556 upper, mag inserts easliy.
If it was mine that would be enough for me to pull a cheap matrix stripped upper out the safe and rebuild it.
Try swapping the bcg's and rerun the test you did with the mag and both uppers and see if the problem repeats itself.
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I had similar issues that were solved by polishing the sharp edges of the extractor. I did not experience the magazine issue however.
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I'm back with an update. Sanders Armory took awesome care of me, and told me the reason I was having clambering issues was the previous owner of the upper replaced the bolt head with another brand. They replaced the bolt head, and said they dry cycled 2 magazines without it locking up. However when I received the upper, I'm still having the same issues. But in looking closely at the differences between my 5.56 upper and the 6.5, the magazine ears are being pressed into the shoulder in the upper receiver opposite the ejection port. That's why I'm having to force the magazines to seat. However the magazines do not have this issue in the 5.56 upper. So I'm getting the feeling either my upper or lower receivers are out of spec. Is there any way to tell which is giving me trouble?
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WickedInexperienced Wrote:I'm back with an update. Sanders Armory took awesome care of me, and told me the reason I was having clambering issues was the previous owner of the upper replaced the bolt head with another brand. They replaced the bolt head, and said they dry cycled 2 magazines without it locking up. However when I received the upper, I'm still having the same issues. But in looking closely at the differences between my 5.56 upper and the 6.5, the magazine ears are being pressed into the shoulder in the upper receiver opposite the ejection port. That's why I'm having to force the magazines to seat. However the magazines do not have this issue in the 5.56 upper. So I'm getting the feeling either my upper or lower receivers are out of spec. Is there any way to tell which is giving me trouble?
I've had that happen before (mags require force to seat), with another brand. Assuming it's doing this with the bolt locked back, your upper is out of spec.
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Yes I'm having this issue even when the bolt is locked back. It's even marking the magazine ears where it's contacting the shoulder inside the upper.
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WickedInexperienced Wrote:Yes I'm having this issue even when the bolt is locked back. It's even marking the magazine ears where it's contacting the shoulder inside the upper.
Yep, they cut the shoulder in your upper too low.
I had a PSA do this (on an FN BBL'ed Upper), and sent it back. They jammed a magazine in there, called it good, and said it's fine, and sent it back. I said no, no it's not fine, I'm having to slam magazines into the gun, and it's doing that on 3 different lowers. So they took it back, jammed a magazine into it, took it off, said it's fine, and sent it back. I said no, no it's not, give me my money back, and take this thing back. To which they said OK. I still buy from PSA, but you have to watch them on this stuff.
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WickedInexperienced Wrote:I'm back with an update. Sanders Armory took awesome care of me, and told me the reason I was having clambering issues was the previous owner of the upper replaced the bolt head with another brand. They replaced the bolt head, and said they dry cycled 2 magazines without it locking up. However when I received the upper, I'm still having the same issues. But in looking closely at the differences between my 5.56 upper and the 6.5, the magazine ears are being pressed into the shoulder in the upper receiver opposite the ejection port. That's why I'm having to force the magazines to seat. However the magazines do not have this issue in the 5.56 upper. So I'm getting the feeling either my upper or lower receivers are out of spec. Is there any way to tell which is giving me trouble?
You already know you have a out of spec upper, now you know double twice it's out of spec.
If the mag works with a diffrent upper and not this one, then the grendel upper is out of spec.
Send it back for a replacment or refund or just buy a blem stripped upper offline and rebuild it with the new upper and then go enjoy your grendel rifle.
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