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Stray Lead


Corey
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Can anyone help, at least point me in the right direction? Built my AR 10 .308 (first build so that could be the answer) and I can not figure out why, but I am unable to get any kind of decent grouping at 100yds, outdoors. First, I thought it was the glass but changed it out to a very reliable one and same thing. I have a Ghost Firearms 18” 308 Winchester HBAR barreled upper. Now my lower is one of those polymer ones from Tennessee Firearms. I went to a knowledgeable and trust worthy parts store and the guy who helped me seemed to know what he was talking about. I did bring the lower with me. I know you have to make sure you get parts that will work with that lower. He assured me all my parts were compatible with the polymer lower. I believed him and had no reason not to. I’m wondering whether it may be a part defect or more than likely builder error. I used a gun rest to limit as much human error I could and bought multiple brands of ammo in same grain but still no good grouping with either scope. Was going to borrow a buddy’s barrel to see if that’s the issue but just trying to figure it out and learn a few things along the way. Any help or advice would be much appreciated. Hopefully it worked but I was able to attach two picks showing parts I purchased. 

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Which different ammo were you using, what weight?  What’s the twist rate on the barrel?  Torqued to spec?

 

and lastly, define “decent grouping”. What were you getting for group sizes?  That may sound like a silly question, but some people consider “decent” to be different things. 

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I used Federal Premium Gold Medal Sierra Matchking in 165 gr, Federal Premium Non Typical 165gr, and Remington Core-Lokt 165gr  

Twist Rate is 1:10

As far as grouping, I marked up two targets to kind of show what I am talking about. Now I am not the best shooter but I group better than this with my other rifles no problem. Usually I can have three around a half dollar size together. When I was shooting it was a cool day and I was making sure the barrel wasn’t getting to hot between shots. I marked up with my finger so not exact representation but it is pretty close. Shooting at 100yds that day and not windy. 
 

I apologize but you will have to elaborate on torqued to spec. 

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3 hours ago, DNP said:

Which different ammo were you using, what weight?  What’s the twist rate on the barrel?  Torqued to spec?

 

and lastly, define “decent grouping”. What were you getting for group sizes?  That may sound like a silly question, but some people consider “decent” to be different things. 

That’s just a couple of groups I remember but if I am remembering correctly, there was maybe only one or two times at the most that my second shot was even in the same plane whether it was horizontal or vertical but still not within a good enough distant to consider it for a decent grouping. 

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I would agree that those are not decent groups for 100 yards. I had to ask, because some call not touching each other “not decent groups”. 
 

I don’t have a lot of input, but saw areas where there may be a few more questions. Hard to imagine a barrel not liking 165’s with a 1-10 twist. 
 

As for the torque, I would want to make sure the barrel is torqued to the required amount and mounted to the upper properly.  It appears to have come as an assembled unit, but it might be worth either A) disassembling and reassembling, or B) sending back to them. Might be worth a call to customer service to see what they say, but if all is assembled properly and you’re using decent ammo and feel confident it wasn’t the shooter - something is out of spec. Did you have anyone else shoot it?  Same results if so?  How does the lower feel when mounted up, fairly snug?  It really shouldn’t be part of the issue, but I’m no expert. Just thinking out loud so to speak and hoping to draw better answers from the experts. 

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Since it came assembled I will look into taking apart and verifying. May call first just to see what they say about it. No one else shot it well at least for hitting a target. There is some room where the upper and lower meet at the but of the gun. I was a little unsure about it and asked a couple of other AR owners who are friends and they didn’t think it was to big of an issue. I found a pic on the internet that resembles what and where I am talking about. I was thinking that may be an issue as well but have been told it doesn’t really hurt but they were no experts either. As far as snug, it does fit together pretty well but there may be a little play if I am remembering correctly. 
side not, my buddy is getting a different upper for his and he is going to let me use his other one to see if I am going to get the same results. 

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