View Full Version : New build won’t group
I took a new build out today to zero. It is a Sionics 14.8 pinned and welded upper. I put a used eotech exps3 on it. I went to zero it at 36 yards and it was printing 4-5 inch groups more like patterns. I figured the optic might be loose. I checked it and tightened it slightly. It didn’t help, I had another rifle out with me so I took the H2 off that rifle put the eotech on and it grouped fine. So I tried the H2 on the new rifle and same 4 inch groups. It varied both in windage and elevation. I am going to contact Sionics tomorrow and I am sure they will help me. I have talked with them before never had an issue but have heard they’re top notch with customer service. I am just curious if anyone on this forum more knowledgeable than me could shed light on what would cause this. I thought maybe an over torqued barrel nut? Looking forward to any thoughts shared.
joedirt199
04-01-24, 07:05
Who did the pin and weld? Could have over torqued the muzzle device if it is one that has to be clocked for to a certain orientation. Check for any impacts on the muzzle device.
I thought maybe an over torqued barrel nut?
I doubt that. I've pulled some Colt nuts off that were installed by Hulk Hogan. Sounds like something Barrel/Ammo related.
4-5" groups at 36 yards? That strikes me as impossible if there is any rifling at all in that barrel.
Also, you use the word build and then reference Sionics upper. Which is it?
I doubt that. I've pulled some Colt nuts off that were installed by Hulk Hogan. Sounds like something Barrel/Ammo related.
Agree. Unless the barrel nut is loose I don't believe that barrel nut torque has any effect on accuracy.
In this case I'd check for a loose barrel nut. If it's not that, then I'd suspect the pin and weld muzzle device install and the barrel itself.
What twist barrel, and what bullet weight? Any sign of the bullet keyholing in target or are the holes perfectly round? Sounds like a barrel that doesn't have a crown, or bullet not matching the barrel twist.
It’s a Sionics complete upper they did the p&w. I was using green tip and shot the same ammo through my Bcm upper, it did okay. I didn’t think maybe the muzzle device but it makes sense. I never had seen a rifle so all over the place that close.
lonestardiver
04-01-24, 13:04
The twist of the barrel may not be fast enough for that longer bullet.
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How well did it group with irons?
4” at 36 yards is well beyond a barrel not liking a particular bullet.
My bet is on the optic or mount.
Barrel is 1-7 and I don’t have irons on it yet. I put two optics on it one was an H2 I’ve had for a couple years now and the eotech did fine on my other rifle
Agree. Unless the barrel nut is loose I don't believe that barrel nut torque has any effect on accuracy.
A loose barrel nut would give you those results. There are people who believe it is harmful to ultimate accuracy for the barrel nut to be overly tight, but that’s not what we are dealing with here.
I've never had anything from Sionics fail to shoot well, to the point I wish I had stacked their LW mid-length barrels deep when they used to go on sale. Please let us know what ends up being the culprit.
Yeah my buddies 16in upper is a laser beam. Everything else I have bought from them has been very high quality. I am sure they will make it right. I am just kind of curious/perplexed.
fedupflyer
04-01-24, 20:27
So many questions for so many variables.
I assume the barrel is free floated.
Is the gas block a clamp-on, screw-on, or pinned?
How much clearance does the gas block have when you put pressure on the barrel or handguard?
Are you running a slim line type handguard?
Yeah it’s free floated. The gas block is screw on. The handguard is sionics mlok. I checked the gas block when I got home today I didn’t see anywhere where it was in contact with the rail. I talked to sionics today and will be sending it in for them to look at. They actually pick up the phone there which is unheard of these days. I am looking forward to seeing what they find. When I looked it over tonight nothing stood out to me. The way it was shooting made me think the mount was loose on the EOTECH. But as I said before it wasn’t and it did fine on my other rifle. This is a weird one. I never have failed to zero a rifle. The guys at sionics seem solid so I guess after they get it I will know if I missed something easy or obvious or if there really is something wrong with it.
titsonritz
04-02-24, 00:08
I've never had anything from Sionics fail to shoot well, to the point I wish I had stacked their LW mid-length barrels deep when they used to go on sale. Please let us know what ends up being the culprit.
SIONICS is top notch, I bought an extra 16” LW and MW Mid-length back in the day just sitting in inventory. Josh and crew have always taken care of me and been responsible to email and phone calls, deal with confidence.
Was there any evidence of bullet strike on the inside of the muzzle device?
Was there any evidence of bullet strike on the inside of the muzzle device?
No. I looked for that last night I didn’t see anything. I pushed on the barrel side to side it didn’t seem to flex any more than my Bcm did in comparison. The Bcm is an elw don’t know if the Bcm would flex more never looked at that before. Outside of the accuracy stuff I really like the upper. The rail seems solid and straight it is gassed properly the recoil impulse is smooth ejection was consistent. Brass piled nice and neat at about 3:30. I don’t want it to seem like I am complaining about sionics at all they have been a pleasure to deal with both about this and I had some questions in the past. I have built a few lowers with their lpk with the enhanced mil spec triggers & I bought an np3 bcg a while back. All have been top notch parts and they have been nothing but helpful. If it does end up that something is wrong with this upper I won’t hesitate to buy from them again. I work in manufacturing and know shit happens sometimes.
I was thinking about it last night while I was looking the upper over and if it is defective my money is on the muzzle device being somehow involved. Just makes the most sense to me. But I’m not an expert
I'm really curious as to what caused this, so report back when you hear from them.
Did you verify the bore was actually rifled? I know of at least one instance where a smooth bore barrel made it into the hands of a consumer, I don't recall the brand off the top of my head but it wasn't Sionics.
I'm really curious as to what caused this, so report back when you hear from them.
Did you verify the bore was actually rifled? I know of at least one instance where a smooth bore barrel made it into the hands of a consumer, I don't recall the brand off the top of my head but it wasn't Sionics.
I'm thinking that was Ballistic Advantage, but it just as easily could have been Faxon.
titsonritz
04-02-24, 13:55
I'm really curious as to what caused this, so report back when you hear from them.
Did you verify the bore was actually rifled? I know of at least one instance where a smooth bore barrel made it into the hands of a consumer, I don't recall the brand off the top of my head but it wasn't Sionics.
22 caliber shotgun
I'm really curious as to what caused this, so report back when you hear from them.
Did you verify the bore was actually rifled? I know of at least one instance where a smooth bore barrel made it into the hands of a consumer, I don't recall the brand off the top of my head but it wasn't Sionics.
It was a Fierce rifle. There was a thread on Rokslide.com forum titled "Fierce firearms disaster". It seems the customer purchased a Fierce rifle, and kept getting high pressure signs with horrible accuracy. He returned it to Fierce who sent it back to him saying "we shot it and all is well". He shot it again with similar results, and ended up discovering the barrel had no rifling in the bore. It seems Fierce missed it on the initial test fire, and again on the subsequent firing when the customer returned it.
He ended up taking to his gunsmith who miked the barrel and discovered that the barrel had only been pilot drilled, and had no rifling.
Yeah it’s rifled I actually did look while I was in the woods shooting lol
Check the barrel extension. I had one that came loose. The alignment pin limits the movement, so I needed to very closely to see. The barrel shot lousy because of that.
It was caused by my incorrect way of removing a tight muzzle device. I should have clamped the barrel shank for that, not the upper receiver. True that the extension should have been torqued so tight to the barrel that it wouldn't have happened, but it did. The barrel manufacturer was nice enough to send me a new barrel.
-TL
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fedupflyer
04-02-24, 19:01
Starting to sound like it may be a bur somewhere in the barrel. If it is, I would guess right around the gas port.
How many rounds do you have down the tube and was any sort break-in done?
I fired a little more than thirty rounds. There was no break in. I was just looking at it again while I was boxing it up to ship. I looked to make sure the barrel was chromed and didn’t see any abnormalities but I don’t own a bore scope so couldn’t really tell for sure. I am going to ship it tomorrow after work. So hopefully I will have some answers in a little time. I figure if they say it’s fine I will get a set of magpul flip up irons and see what happens. I guess that will be the best place to start.
Strikefirst
04-03-24, 18:57
Every company makes an occasional dud. Looking forward to the results. Good luck.
Yeah last year I had a Bcm bcg that sheared the fasteners for the gas key it wasn’t locking back on empty magazines they replaced it and I have had no problems with that upper since. It is extremely accurate and just works great. It can happen even with quality stuff
A loose barrel nut would give you those results.
That is the first thing I thought of as well.
Heavyweight
04-22-24, 10:36
Bump…..curious if you found out the cause. I had the exact issue once upon a time. It was my Eotech. Wouldn’t hold zero. New out of the box.
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I am in the process of everything with sionics….don’t want to give an update till it is over and I know everything for sure
Fair enough, I too am interested, glad this one got bumped.
Gunpartpicker
04-23-24, 22:36
Hopefully it was just a lemon and they get a new barrel back to you soon.
So here’s what ended up happening…. They took the upper out and shot it last week. The guy forgot his bipod and shot it at 36 yards using an eotech.He used three different ammunition types the groups ranged from 2-3 inches it appeared. The smallest being black hills match grade 77gr. He said he thought it was okay because he was just using a mag as a monopod. I asked that he shoot it again with a bipod. Groups were smaller than I got but still not good. He shot it yesterday at 100 with a bipod, rear bag, and 1-10 on it using the match grade black hills. He got about a 2 1/4 inch group. Once again not good in my opinion although it seemed to be getting better each time it was shot. He agreed it wasn’t great and they are going to put a new barrel on it. Today is their Friday. He said I should have it back in a week/week and a half because it has to be pinned and welded. I am happy with the outcome. They are going to group it before they send it back so they are making things good and standing behind their product.
The customer complaint was poor accuracy, so they initially tested it with an unmagnified optic at short range? That's ridiculous. I'm glad they consider 2.25 MOA to be not good enough, but it sure doesn't explain why their results are so much better than yours.
I've got a couple Sionics' ARs, but their 11.5" barrels has caused me to not shoot them for groups at 100 yards yet.
They wanted to see if they had the same results as me. Because I had only fired it at 36. I never zeroed the gun, because I never felt it grouped well enough to adjust off of. Although I was surprised he thought 2 inches at 36 yards with match grade ammo was okay, ultimately they are making it right and I will continue to be a customer.
This tells me there was something wrong with your setup.
Good that they are replacing the barrel......BUT there is a Grand Canyon of difference between 4-5" groups at only 35 yards and their 2" groups at 100. Which is actually very acceptable for a fighting rifle.
Possibly…. I am fairly experienced and never had those issues before and have zeroed a ton of rifles. Both my own in and out of the military and friends new to shooting especially after the summer of love quite a few co workers bought rifles with no experience. I am not an expert though and I would say I screwed up somewhere but that same day set up the same way put that EOTECH on my Bcm rifle and things were fine. Like I said I am happy with what they are doing for me not bashing sionics at all. Once I get it in hand I will take it out and go from there. I started the thread because I was curious what others thought. I may have been at fault. I originally thought that the optic must have been loose and checked it seemed solid but tightened it a little anyway. Tried my aimpoint I’ve had few years and know is good with the same results. Then put that back on the Bcm and was fine. It was pretty weird. But I may have over looked something stupid that would explain things.
So I got my upper back a couple days ago. I took it out yesterday and it zeroed just fine. With the same EOTECH on it. It is really accurate and gassed perfectly in my opinion. I believe something was wonky with the original barrel. I am happy with the way it turned out. This may be my new favorite rifle.
Very nice! I'm glad they resolved your issue.
Outstanding news. Thanks for providing the follow-up report.
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