Same here. Got 3 of my most often offending magazines loaded with SADU (Romanian 62gr), IMI 55gr, & AE LC 55gr. Also tossing in the 10rd D&H (Sig) mag with PMC XP193. All bagged and ready.Originally Posted by georgeib
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Same here. Got 3 of my most often offending magazines loaded with SADU (Romanian 62gr), IMI 55gr, & AE LC 55gr. Also tossing in the 10rd D&H (Sig) mag with PMC XP193. All bagged and ready.
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I got a chance to run 137 rounds of ammo thru the repaired P516 that was sent back to me on Aug. 29th. All fired ammo was on suppressed setting with my Sig SRD516 suppressor screwed on. Outlined below are the results:
The rifle was fired from a bench rest.
Palmetto Armory metal 30rd magazine / IMI 55gr M193 FMJ BT:
2nd round had a failure to feed. Bolt carrier stopped ~5/8" from closing & against the jammed round. The bolt extractor was not locked to the round so I easily pulled it back without the round attached but round is stuck in the chamber and bent. The round requires pushing out from the front with a cleaning rod. Or I can bring the carrier back all the way using the charging handle and release so that the bolt slams against and locks the cartridge. I can then extract the round with great difficulty by pulling hard on the charging handle.
See pix. Notice the bent and scratched unspent round.
A few minutes later using (original Sig D&H 10 rd) I had a failure to feed when simply dropping the bolt release to chamber the fresh round. Using the same IMI 55gr. ammo. The round came from the right side of the Sig magazine. Again, notice the bent and scratched unspent round that I had to push out of the chamber from suppressor end. There is no way this gun should be this sensitive to ammo brand. See pix.
I decided to try a different ammo and magazine. This time using PCM 55gr XM193 FMJ BT and a PMag GenM2. It only took 3 rounds to get a failure to feed. Notice the big scratch.
Tried the IMI one more time from a PMag. Jammed in just a few rounds. This is getting old....
Changed ammo --- Frontier 75gr BTHP from a PMag and jammed in just a few rounds fired. Again from the right side of the magazine.
Again, the video can be viewed at
Fired a full magazine of 62gr XM855 and a full mag of American Eagle 55gr XM193 without any fails. How can this gun be this sensitive to type or brand of ammo? Five jams in 137 rounds fired is nearly a 4% fail rate. Totally unacceptable. I have to trust this gun!
As a side note, it makes no difference when using the Sig upper if it is suppressed or not. The fails happen both ways and on different gas settings.
As a test, I swapped the upper to a 11.5" DI and fired two full magazines using the magazine and ammo with the highest propensity of failure to feed. (Palmetto State Armory 30 round metal with the IMI 55gr M193 FMJ BT and PMC 55gr XT193 FMJBT from a PMag 30rd mag). That ammo and magazine combination had zero issues when fired thru the different upper assembly.
As another test I took my son's stamped lower SBR and while he supervised as per the ATF regulations, used my Sig upper and had similar fails with various ammo and magazine combinations.
I'll be sending this gun back to Sig for the 3rd time. I really think I should get either a new barrel or upper from Sig. I offered to send them a selection of ammo and magazines but have not heard back yet. Their communications are rather slow and sometimes non-existent.
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Did you try swapping to another bolt carrier group all-together? I saw where you've replaced the extractor. When you send it back to Sig, be adamant that you want them to check and make sure that the barrel extension is clocked correctly as well as headspacing and they need to use go/no-go gauges on it.
Last edited by Hexxus; 09-02-20 at 13:00.
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It's just really odd that all of the malfunctions are initiated from the right side of the magazines and correspondingly, the right feed ramp. My son thought of swapping the BCG a few weeks back but I've been unable to lay my hands on a piston BCG to try out. It might not be a terrible idea to have one laying around as a spare but a bit pricey.
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I noticed that too, and then I looked closer at this;
That's why I started questioning if the barrel extensions was clocked or in-spec. It looks like your feed ramps on the right side are misaligned slightly compared to the left, and it looks like you have a carrier impact on the lug channel from something being out of spec. Are you able to tell if the barrel nut is tight or loose? Can you get a picture of the face of your bolt?
Last edited by Hexxus; 09-02-20 at 13:18.
Member
https://i.imgur.com/rWNdScf.jpg Sig has had it for feed ramp service twice and they cannot get it to malfunction. And if it was just one ammo, I could work around that. Just too many different types and magazines to be doing this. Swapping uppers and lowers only points to the Sig upper as source of failure. The barrel nut is aligned with the piston rod (it goes thru a slot in the nut). I've seen the small marks on the lugs but the round begins going out of alignment well b4 the bolt gets to the lugs so it is the bent misaligned un-fired round that stops the bolt.
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Don’t know if this has been mentioned yet, but is there a burr at the end of the feedramp, where the bolt lug passes through? The rectangly bit. I’ve seen a few barrel extensions that kinda grab the round there.
RLTW
“What’s New” button, but without GD: https://www.m4carbine.net/search.php...new&exclude=60 , courtesy of ST911.
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
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No. In my original pix, there was a spot that was catching some brass and gouging a big scratch on any round that got jammed and bent. After the most recent polish/repair by Sig, it's doing it to a lessor degree now. The bolt moves easily to the lugs and slips in and locks with a snug feel. No dragging or momentum change.
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Roger. You wouldn’t feel what I’m talking about via empty bolt. The bolt doesn’t snag. But, you would see scratches on the projectile itself, which I don’t see on this picture. So, I dunno.
RLTW
“What’s New” button, but without GD: https://www.m4carbine.net/search.php...new&exclude=60 , courtesy of ST911.
Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.
Member
Mailed gun back to Sig today. Think they will replace barrel and BCG
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