Ejection Routes Inconsistent

[georgeib]

That's the general idea... However, that would constitute creating an unlicensed SBR, as the Springfield lower isn't registered with the ATF... I would suggest that you find a pistol lower to experiment with.

[jpmuscle]

That's the general idea... However, that would constitute creating an unlicensed SBR, as the Springfield lower isn't registered with the ATF... I would suggest that you find a pistol lower to experiment with.

We’re truly our own worst enemies time and time again . Do you feel better about yourself when you go to bed at night?

Op, do what you gotta to reduce down and eliminate potential points of issue.


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[georgeib]

We’re truly our own worst enemies time and time again . Do you feel better about yourself when you go to bed at night?

Op, do what you gotta to reduce down and eliminate potential points of issue.


Sent from my iPhone using Tapatalk

SMH... Do you really want the guy walking out onto a public range with an unregistered SBR, with no idea what he's inadvertently done?? I certainly don't! If the OP chooses to do so, let him do it as discreetly as possible, and without having discussed it on a public forum.

[tehpwnag3]

Does the action cycle smoothly by hand, with and without ammo?

How many rounds through the gun? If thousands, you might want to replace the extractor and ejector springs.

Measure the free length of your action spring against minimum spec.

What brand of magazine do you use? Do these problems occur with all of them? Do you number your mags?

When was the last time you scrubbed your chamber with a good solvent? Mop patch comes out clean?

Clean out all of the grease. Use a little bit of CLP or a cheap motor oil to eliminate the possibility that the action is gummed up with thick, carbon-laden grease. Keep your action spring clean with just a thin application of oil. Check out Quib's pictorial of lube points and amounts.

[tehpwnag3]

I see that you mentioned only 500 rounds through it. Check and try the things I've mentioned above. However, your 10" piston gun may be finicky at best, or a lemon at worst.

It's your money, but $17 for a tiny bottle of magic unicorn jizz makes me want to puke. I'm thinking fondly of my $7 quart of Mobil 1 10w30 that lasted me well over 15 years in multiple platforms, and in various environmental conditions, including several 1k round classes.

[masterdrago]

George, thanks for the reminder about the other lower & SBR "issues" :+} Would only be used a short time like that and not on any public range.... and to tehpwnag3, the action seems very smooth without ammo... but using American Eagle brand XM193 55gr out of a Tapco plastic magazine, hand cycling would jam every 5-10 rounds. I pulled back, the round ejected. I let the spring drive the bolt back to battery, taking the new round with it to chamber. Several times in 30, the bolt did not close all the way. I had to drop the mag and hit the forward assist to force the bolt to lock and grab the round. See pix of two bent. https://imgur.com/pLB4sBY

The spring measures to spec. Maybe 500 rounds. It was sent back to Sig and they ground the feed ramps a bit. I've not tested with the steel Palmetto State Armory mags nor the Isreali boat-tail M193 ammo. Mostly use PMag M2 & M3. I'm going to clean the bore today. Just got the bore brush w/dewey rod. Ordered from AMZN and kept getting the .308 bore brush. Will let you know.

[tehpwnag3]

Stick with Pmags or known-quality USGI. Tapco parts and accessories are not confidence inspiring in my experience.

I'm at a bit of a loss at what Sig needed to do. Grinding on feed ramps post-production, when you are having feeding issues, is not good. I really hope you get your SBR running right.

[masterdrago]

I just cleaned the bore and ran two mags each of XM855 and XM193 though it fairly fast. Had a failure to close the bolt in each mag but not at any particular level of the 30 round mag. Bolt was within 1/4" of home but roundwas not against the bolt face. Had to drop mag and pull back charging handle to get to battery. Adjustable block set on suppressed setting. The XM855 62gr exited close to 3:00. The XM193 at closer to 1:30. I need this gun to be reliable.... https://imgur.com/iQdTjHx Do I get with Sig again? I've made some changes so they might not warranty - SSA trigger, POF adj stock, Sig suppressor. I can undue all of that but painfull. It's engraved due to Form 1 Trust. I would like to figure this out so I learn more about my AR behavior. Really appreciate the help and suggestions.

[tehpwnag3]

I see a Dewey brass cleaning rod but no chamber brush... It is unlikely that a dirty chamber is causing issues, but we're trying to eliminate possibilities.

Between the bolt and barrel extension (or barrel) something isn't right. When you had failures today, did the cartridges get bent and dinged up again? Can you post a clear and close picture of the feed ramp area? I would like to see the upper receiver/barrel extension interface.

Remove the bolt carrier group. Manually move the bolt back and forth. Any sticking points? Disassemble the BCG and give it a good cleaning and lube, if you haven't already.

If you're not comfortable with what you are seeing and feeling, you'll want to reach out to Sig and tell them what is happening and what you've tried. At the very least, take it to a knowledgeable armorer for a once over, if you can.

[masterdrago]

I see a Dewey brass cleaning rod but no chamber brush... It is unlikely that a dirty chamber is causing issues, but we're trying to eliminate possibilities.

Between the bolt and barrel extension (or barrel) something isn't right. When you had failures today, did the cartridges get bent and dinged up again? Can you post a clear and close picture of the feed ramp area? I would like to see the upper receiver/barrel extension interface.

Remove the bolt carrier group. Manually move the bolt back and forth. Any sticking points? Disassemble the BCG and give it a good cleaning and lube, if you haven't already.

If you're not comfortable with what you are seeing and feeling, you'll want to reach out to Sig and tell them what is happening and what you've tried. At the very least, take it to a knowledgeable armorer for a once over, if you can.

Definitely used the chamber brush, but I will follow the suggestion and clean it again along with a thorough clean and lube of the BCG after checking it for smooth movement which seemed good every time I've had it out and or disassembled. I did not ever eject the round that may have caused the fail-to-lock. I just pulled back on the charging handle, saw that a new round was in the chamber, and let fly. When I did that, the bolt went to battery and I fired the rest of the mag. Should have checked the spent casing but did not. Feed ramp pix ... https://imgur.com/PSvhUay https://imgur.com/zv0PvQL

I'll do a bolt clean and lube tomorrow and test again.