Ejection Routes Inconsistent

[masterdrago]

I'm seeing very inconsistent ejection routes when firing a full mag of ammo. This happens mostly using either 55gr AE XM193, 62gr AE XM855, or other low cost ammo. I sometimes get failure to seat a round (bolt not closing all the way) and will get FTF then. If I push the forward assist, it will close and then successfully fire. I've had off and on issues with this same problem since getting the Sig P516 10" which I've replaced the brace with a adjustable stock (Form 1). Sent it back to Sig early on and they ground the feed ramps which vastly improved the cycling. B4 that, new rounds out of the mag might jam going up the ramps. They would literally be bent and dented. Ammo that gives no issues is the Hornady 75gr TAP SBR which ejects at 4:00. I've tried different lubes but mostly have been using the TW25B and once even lubed the bolt lugs with a generous helping of grease (got 80% failure to lock). It's suppressed if that matters and am using on the suppressed setting but the ejection pattern is just all over the place. Has anyone tried using the Black Rifle Balm from Cherrybalmz? Can anyone give me some suggestions on this issue?

[26 Inf]

You talking about lube causes me to ask if you are lubing the gas piston or the valve itself. Generally this is a no-no for piston systems as some lubes will cause the systems to carbon up quickly.

[masterdrago]

No lube or any work on the piston or the adjustable gas block. In my most recent cleaning and re-lubing, I was careful to only lube using the instructions at https://www.cherrybalmz.com/post/how...um-reliability. Prior to that I was using a diagram at https://www.ar15.com/forums/ar-15/-/7-548967/ which had me greasing the bolt lugs and gas rings & firing pin which cherrybalms says not to do. So for a novice AR guy, it just gets confusing. And with no experience with an AR except the 500 or so rounds through this Sig 516 10" + suppressor, I'm mystified as to the variation in spread location of ejected ammo. Also an occasional round getting chambered b4 a spent round completely clears the box so you have a spent casing facing in between the bolt and chamber. My son said it was something he had never seen and he shoots often.

[georgeib]

Are you having these same issues unsuppressed too?

[masterdrago]

Are you having these same issues unsuppressed too?

It's been a long time since I've run it un-supressed but yes, intermittent jams and a few failure to close the bolt all the way. I was planning on taking it to the range on Friday but may have to delay that. I'll work through the 3 possible ways (non supressed, supressed, and gas block setting change) with the same ammo in a bit. Will try to document better.

[georgeib]

I would try a new and/or heavier action spring, and an H2 buffer. Also, I like to lightly grease my action springs and the inside of the receiver extension, as far as I can reach in. Really smooths out the action.

I also lightly grease the bolt carrier rails, and the outside of the charging handle. Manually cycle it until you feel it smoothing out.

[Dr. Bullseye]

Isn't this worth considering?

"This happens mostly using either 55gr AE XM193, 62gr AE XM855, or other low cost ammo"

Maybe the loads with this ammo are not consistent. Wouldn't this cause both cycling and ejection inconsistenties? You say it gets better with better ammo.

[masterdrago]

Isn't this worth considering?

"This happens mostly using either 55gr AE XM193, 62gr AE XM855, or other low cost ammo"

Maybe the loads with this ammo are not consistent. Wouldn't this cause both cycling and ejection inconsistenties? You say it gets better with better ammo.

Yes, to some extent. I've had very little if any issues using Hornady 75gr TAP SBR ammo and the ejection location is about 6+ feet out at the 4:00 position. I've been using the much lower cost ammo to just practice operation and get myself better accustomed to handling the new-to-me AR. The gas gun I have (Springfield Armory Saint Edge) seems to handle any ammo launched with ejection patterns holding firm from 2:00ish to 4:00ish depending on make and model of ammo. I still plan on taking the Sig out for more detailed documentation of each ammo issue. Maybe do it at home @50yds. My son brought over some SADU stuff which I had never heard of and the Sig did extremely poorly with it. I've gathered from reading both the M4 forums and a few others that 10" piston platforms are persnickety. I'm just wanting to make the best of it and get it working better for practice. More or better lube or like georgeib said, maybe switch out the buffer for a few $$. Spring measures the right length and is lubed well.

[georgeib]

I'm wondering if something in the piston system may be very slightly misaligned, and is causing just enough of an issue sometimes. Or, if issue is timing.

Try swapping the upper to you Saint lower and see if it fixes the problem. Or a "pistol" lower of some sort...

[masterdrago]

I'm wondering if something in the piston system may be very slightly misaligned, and is causing just enough of an issue sometimes. Or, if issue is timing.

Try swapping the upper to you Saint lower and see if it fixes the problem. Or a "pistol" lower of some sort...

So I'm pretty green at this ... so take the Sig upper including BCG and drop it into the Springfield lower with its trigger group and rifle receiver extension, action spring and buffer assembly? And see how they play together?