User Panel
User Panel
User Panel
USA
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Posted: 6/2/2024 11:33:50 AM EDT
Criterion barrel
Toolcraft BCG Just assembled this upper and notice some potential contact points on the barrel extension. I have assembled several AR 15s and haven’t noticed this issue in any of them, but this is my first large frame build. Any advice is appreciated.   
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Posted: 6/2/2024 5:55:47 PM EDT
[#1]
Was it like that prior to installation, or after cycling the action several times?
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Posted: 6/2/2024 5:56:09 PM EDT
[#2]
What does the front of the bolt look like?
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USA
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Posted: 6/2/2024 9:59:54 PM EDT
[#3]
Quote HistoryOriginally Posted By borderpatrol: What does the front of the bolt look like? Here are some pictures of the bolt. Doesn’t look to have much wear in the same places to me. Unfortunately I don’t have any pictures of the barrel extension before assembly.  
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Posted: 6/3/2024 6:38:09 AM EDT
[#4]
I would send the pictures to Criterion, to see what they think.
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USA
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Posted: 6/3/2024 9:20:31 AM EDT
[#5]
Quote HistoryOriginally Posted By borderpatrol: I would send the pictures to Criterion, to see what they think. Good call, I will do that. |
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Posted: 6/3/2024 9:34:56 AM EDT
[#6]
Hard to tell exactly, but do the ramp cuts line up perfectly with the upper or are they slightly skewed clockwise?
Might be an issue with the alignment pin notch in the upper, I've seen it before. |
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Posted: 6/4/2024 3:50:29 PM EDT
[Last Edit: TonyRumore]
[#7]
What kind of tool were you using to hold the receiver, when you torqued the barrel nut?
Tony |
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USA
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Posted: 6/4/2024 10:29:06 PM EDT
[#8]
Quote HistoryOriginally Posted By TonyRumore: What kind of tool were you using to hold the receiver, when you torqued the barrel nut? Tony I used a Midwest Industries action rod. I did notice that the lugs on the action rod were pretty sharp so I am wondering if I bubba’d it when I was sliding it on. |
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Posted: 6/5/2024 8:27:33 AM EDT
[Last Edit: TonyRumore]
[#9]
Check and see if the barrel may have rotated in the receiver when you torqued it down.
You might try just pulling back on the nut a bit and see if the barrel will rotated back a bit. If that receiver is 6061, and you hold it with a reaction rod, it's pretty easy to drag the barrel over off top dead center when tightening. The MI unit does have a flange to help prevent it, but it doesn't fit all that securely in the charging handle slot. Tony |
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LA, USA
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Posted: 6/10/2024 4:06:34 PM EDT
[#10]
If I have things right in my head, I would imagine that could happen if the bolt started rotating too early, but I can't imagine what would cause that to happen, especially with all new quality parts. Maybe you could get that happen if you assembled the BCG without the firing pin in place and tried to slam the bolt home.
Still, I would think that if it was caused by a misalignment of parts, there would be corresponding marks of some sort on the bolt. My guess would be that it happened during install. Please post when you figure it out. Looks like a learning moment. |
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USA
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Posted: 6/10/2024 4:56:47 PM EDT
[#11]
Alright think I have it figured out.
I believe it’s not the bolt that gouged it, but me slipping when sliding it onto the action rod. The lugs on the action rod are fairly sharp so I fell confident that it’s user error on my part. I need to find time to go shoot it. I’m hoping that the gouges will not effect function. |
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GA, USA
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Posted: 6/10/2024 4:57:15 PM EDT
[#12]
Quote HistoryOriginally Posted By TonyRumore: Check and see if the barrel may have rotated in the receiver when you torqued it down. You might try just pulling back on the nut a bit and see if the barrel will rotated back a bit. If that receiver is 6061, and you hold it with a reaction rod, it's pretty easy to drag the barrel over off top dead center when tightening. The MI unit does have a flange to help prevent it, but it doesn't fit all that securely in the charging handle slot. Tony Agree with this, in addition the teeth on the spline on the MIURR are to narrow thus a sloppy fit in the barrel ext along with the fin in the charging handle slot. This tool aint bad but not near as good as all the hype. There is a better tool. |
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USA
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Posted: 6/10/2024 5:30:25 PM EDT
[#13]
Quote HistoryOriginally Posted By OTDR: Agree with this, in addition the teeth on the spline on the MIURR are to narrow thus a sloppy fit in the barrel ext along with the fin in the charging handle slot. This tool aint bad but not near as good as all the hype. There is a better tool. What tool would you recommend? |
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GA, USA
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Posted: 6/10/2024 8:50:13 PM EDT
[#14]
Quote HistoryOriginally Posted By Maddy21: What tool would you recommend? 2 Unique barreling spud. Its more expensive than MI URR but can also be used for USGI barrel nut alignment. The teeth on the spline are wider than on the MI URR and thus no barrel ext slop. The fin can be shimmed as shown in this pic with metal tape like HVAC techs use. On 3 uppers I just checked, BMC UPPER did not need to shim the fin, a used S&W upper and a new Colt upper does. Its kind of hit and miss on the fin but it needs to be able to fit the smaller spec uppers. 
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USA
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Posted: 6/12/2024 12:10:47 PM EDT
[#15]
Looks good, thanks for sharing
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