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AR10 not cycling


X5SigChris

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This may be premature but it’s really bugging me. I have an AR10 I built and finally got to zero it today. It did not go as planned. It won’t cycle at all. Bellow is a list of parts for reference:

 

aero upper receiver

rainer arms ultra match 20” barrel 

SiCo muzzle brake

aero bolt

raptor CH

salient arms adj gas block (forgot the Allen wrench to adjust)

 

Lower is an Aero pre-built lower 

 

ammo today was freedom munitions 168Gr hornady A-max (I know. Not the best. Don’t kill me) 

 

was running a Omega 36m can. 
 

so while shooting, it fired fine. However, there was zero movement of the bolt. I thought I didn’t seat the mag well but still no luck. Trying to manipulate the CH was work. Felt like a bulged case was stuck but all the cases look good minus two small parallel scratches on the neck. Every case has it. Sometimes it was easy to rack the CH. sometimes I had to beat the rifle. 
 

I was hoping it was a gas issue but that doesn’t seem to be the case. Any direction would be greatly appreciated before I start really digging into it. Thank you. 

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Is that freedom ammo their reloads? If it is they probably didn't small base die it. That combined with some ar10 barrels are to tight to begin with causes them to get stuck. You could dychem the rounds or just use a sharpie to see where they are binding. It could also be your head spacing but that's rare these days, wouldn't hurt to check or have it checked. 

 

What makes you think it's not a gas problem for the cycling? That's pretty much always the problem. How did you line up the gas port? Do you have a bores cope to check it? Open that gas block all the way up. 

 

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So initially I thought it was a gas issue. But I’m leaning away from it now. I chambered a round and had the same issues of the bolt sticking. No firing. Just chambering and clearing.  
 

it’s new freedom ammo. I have some other brands, just not with me. 

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2 minutes ago, RJH said:

I'd try not freedom munitions ammo first 

You’re not wrong there. Honestly, I placed a large order with different ammo and this was my first bad experience. I’ve shot north of 5k freedom rounds but mostly just plinking. This year, getting back into USPSA, I had numerous failures. So I’m not to far off of adding this to that list. Haven’t bought from them since that last order and moved onto another brand. 
 

I have some snap caps that will be in Tuesday that may be able to help me isolate the issue. 

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I'd start with gas block alignment then headspace. Also, does an unfired round eject easily.

 

Edit: just refreshed and saw more info in the posts after the OP. Sounds like you're headed in the right direction.

Edited by TonytheTiger
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49 minutes ago, TonytheTiger said:

 

I'd start with gas block alignment then headspace. Also, does an unfired round eject easily.

 

If by easy, you mean having to use two hands on a good round and banging it against my tailgate on others… sure. 😂

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18 minutes ago, X5SigChris said:

So. If it were a headspace issue. Simple solution would be to shim the barrel one way or another depending on how it gauges correct. Now I’m second guessing myself 

No. That's not how AR barrels work. Assuming the bolt is in spec about all you can do is hand turn a chamber reamer to your desired headspace. I've done it on a couple tight chambered AR15 barrels that needed to be able to eat any and all ammo. Definitely rule out gas and ammo issues before this though.

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@TonytheTigeri thought about what I said about shimming it the other night. I’m not sure why I said that haha. I was frustrated I had a really expensive, terrible bolt action gas gun lol. 
 

the gauges haven’t arrived yet but the snap caps did. I know it’s not the same by any means but I had to see if it cycled. It does. Load the mag, send the bolt home, rack the CH, ejects cap. Works fine. Seems that the ejector spring may be a touch stiff as sending the bolt home about a 1/4 of the way forward will load the next round but not attach to the rim of the case. Either way, possibly another issue at another time. 
 

makes me question that my chamber profile may simply not like the hornady a-max bullet. Maybe that isn’t the case at all. But for information, here’s a list of some measurements from the rounds used to the cap. 
 

freedom munitions:

rim diameter 0.465

neck diameter 0.340

OAL 2.790

 

snap cap:

rim diameter 0.465

neck diameter 0.335

OAL 2.493

 

maybe this can help in solving the issue until more tools arrive. 

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If the bullet is running into the rifling you'll see evidence of it on the bullet. The Amax is a pretty secant ogive so you typically don't have trouble hitting lands unless loaded really long. More likely is that the shoulder isn't bumped back far enough. You'll have to compare shoulder locations. You could also black marker the whole case and see if it shows where the stickiness is happening.

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I haven’t marketed them yet. I need to. However I am talking with the barrel manufacturer as well. Of course, he’s trying to rule out every other part minus the barrel. And he may very well be right. I have plunk tested three other brands and one falls out freely. The other two need a bit of a love smack on the receiver. 
 

I don’t see any signs of the round hitting the lands on any of the test rounds I’ve been trying. 

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