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crossbow5

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I had same problem with an AR-15, but would not lock the bolt back. Discovered that one of the bolts that attaches the gas key to BCG had broken and gas was leaking. It took a while to figure it out, but I found a video on YouTube where another guy had the same problem. I had tried other magazines and still would not operate like it should. I replaced with another BCG and problem solved. I later got the broken bolt removed and replaced and the original BCG works great. Edited: "would not operate like it should"
 
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You still don't mention your gas system type. Also, if your gas block is pinned it's relatively easy to remove the handguard, pop the pin, and move the gasblock so you can inspect for centering and check size. If it's centered correctly you should have a carbon ring completely around the port. To check the size of the port pull out a set of small drill bits and check size by inserting drill bit shanks in the port. Another thing to check is that the gaps in the bolt gas rings aren't lined up. If they're lined up they're not sealing.

EDIT: Found in your pics of labels that the barrel looks to be rifle gas. Port size should be around 0.0960".
 
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Thank you!
Entire build is Aero Precision
There is no cross contamination of M4 to M5
Gas block is aligned and air passes freely
No gas key as I do not believe it is adjustable style
I’m thinking I purchased a Aero P carbine length buffer tube When what I needed was a rifle length buffer assembly. To much tension fir BCG to cycle back with carbine spring...
thoughts?
Going through the exact same thing. I'd swear your re-writing my post. I'm waiting on a break from some rain and wind to find out if ^^^ was my exact issue. Good luck. Irritating isn't it?
 

po18guy

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It racks fine, heavy but fine.
Buffer I assume is standard. When ordering I did not see option for HD version.
did not try multiple mags should have...
Do not want to pull upper apart to check gas tube placement till I talk to Aero Precision...
Racks heavy, you say. Too much spring? If so, the bolt is not traveling back enough to catch the second round.
 
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Copy that... Thank you for your help! Back to range this weekend. I have a call into Aero Precision as upper was built by them reluctant to tear into gas block and such without them involved.
I'm suspicious of me using a carbine buffer assembly vs a rifle buffer...
I built my .308 M5 with the Aero carbine buffer tube. They sell rifles configured like that.
 

Goodknight

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You still don't mention your gas system type. Also, if your gas block is pinned it's relatively easy to remove the handguard, pop the pin, and move the gasblock so you can inspect for centering and check size. If it's centered correctly you should have a carbon ring completely around the port. To check the size of the port pull out a set of small drill bits and check size by inserting drill bit shanks in the port. Another thing to check is that the gaps in the bolt gas rings aren't lined up. If they're lined up they're not sealing.

EDIT: Found in your pics of labels that the barrel looks to be rifle gas. Port size should be around 0.0960".
Thank you
 

Goodknight

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Going through the exact same thing. I'd swear your re-writing my post. I'm waiting on a break from some rain and wind to find out if ^^^ was my exact issue. Good luck. Irritating isn't it?

Absaflippinglutely!!!!!
Left a message this morning at Aero Precision tech support waiting for a call. Maybe tomorrow.
left another message at my gun smith no call. Maybe tomorrow... I will pass on anything I learn Cannonman!
 

223to45

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I run a 308 with ValtorA5 tube, 308 rifle spring, and a 8oz AR15 buffer, runs smooth as butter..

I might have missed it if you said it., but are you able to pull the bolt back far enough to use the bolt catch to lock the bolt open??
 

Goodknight

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I run a 308 with ValtorA5 tube, 308 rifle spring, and a 8oz AR15 buffer, runs smooth as butter..

I might have missed it if you said it., but are you able to pull the bolt back far enough to use the bolt catch to lock the bolt open??
Yes I can pull lock bolt open.
thank you for your comments!
 
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Thx, BTW my build also was all Aero P. No one near me to mentor. All I've ever learned was through reading and trying. The guys here? I wish I could even pay to be an assistant. I've met some fun guys who work in the field. Bill, at BSF has years as a military armorer. He's been great. I think I'm going to try a 6 ARC as my next build. Also on an AR platform. There was a magazine write up that showed an AR Ruger in 6 ARC. It was hitting 5" groups at 1K yds. I'm not a huge fan a Ruger other than good bang for $$$. I'm in a point of wanting to spend a bit for the diminishing return. But when ya get hit with what you and I are both going through you begin to wonder. I also chatted with a few gun manufactures and silencer manufactures at the last NRA. I don't think we're anywhere near alone with having problems that just stymie the builders. Or check out any custom car show and see a parallel problems. The best guys in the industry and they can't get the car to start. I believe we are both going to get these to run. And I really enjoy all the help the guys here are so willing to give. Gives you a sense of friendship backing up your efforts. Hope to show a tiny ragged single hole and a big smile on my face on day soon.
 

Goodknight

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Last night I pulled gas block assembly back and confirmed that barrel port was clear, gas block is standard AP non adjustable. Air blows through freely... Disappointed that barrel did not have dimples where gas block screws would "align" gas block at center. Seems like guess work to get GB and barrel port aligned.
Hand cycled action approximately 200 times grumbling the entire time about doing a seemingly unorthodox process on supposedly a "plug and play" program!!!!
Yes you can hear my frustration!!!
For what it is worth:
Bolt hold open when mag in place
Bolt does lock open on bolt latch...
Left message at Aero Precision yesterday morning hopefully will hear from them today.
Back to range Friday will bring several different magazines and plenty of lube for BCG.
 

Goodknight

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I run a 308 with ValtorA5 tube, 308 rifle spring, and a 8oz AR15 buffer, runs smooth as butter..

I might have missed it if you said it., but are you able to pull the bolt back far enough to use the bolt catch to lock the bolt open??
How did you come up with this buffer tube configuration? Trial and error?
 
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NO.

The A5/A10 tube is 3/4" longer allowing for rifle spring use, and a standard AR15 buffer, instead of the super short harder to find options for 308 buffer.

Is a well known combo.

Just wanted to smooth out the recoil, since it will be suppressed.
Solid advice.
The Armalite AR10 carbine receiver extension, which used to be called "intermediate length", is the same inside depth (7 5/8" - 7 3/4") as a Vltor A5. The compete Armalite package (RE, buffer and spring) is compatible with the DPMS pattern rifles, and is usually sold at the Armalite website for a decent price, but I have no idea about current price and availability.
Standard carbine RE's have a depth of 7", which require the use of a short buffer (2.5") when used in the 308 platform. Aero's carbine 308 buffers weigh 3.8 oz (for various reasons). Many builders use a buffer weight of around 5.5 oz. The heavier weight helps with "bolt bounce" and slows the action down, which I believe is the source of your problem. I've used Kaw Valley Precision 308 buffers (5.6 oz) in the past. Slash's Heavy Buffers is another source and has a lot of info at their site and will help you if needed. There are some downsides to using a heavy buffer, specifically a higher rate of broken bolt catches (especially early Aero's), so pay attention to the distance between the bolt face and the bolt catch at max pull of the CH.
Another way to tune the rifle is by changing the action spring. Check out David Tubb's website, he has a lot of info and a lot of people swear by the Tubb's Flatwire Spring. Sprinco also is a reputable source.
One last thing is concerning the gas system. My personal experience with the Aero 18" using rifle length gas is they port it out at 0.089". If you remove the gas block again, it would be helpful if you measure your gas port, typically done with pin gauges but numbered drill bits work .I believe that the 0.089" gas port is about right. I do run adjustable gas blocks on a couple builds, but my intent is not to unless running suppressed and unsuppressed on the same rifle There are a number of other ways to tune the gas system other than AGB's.
 
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Solid advice.
The Armalite AR10 carbine receiver extension, which used to be called "intermediate length", is the same inside depth (7 5/8" - 7 3/4") as a Vltor A5. The compete Armalite package (RE, buffer and spring) is compatible with the DPMS pattern rifles, and is usually sold at the Armalite website for a decent price, but I have no idea about current price and availability.
Standard carbine RE's have a depth of 7", which require the use of a short buffer (2.5") when used in the 308 platform. Aero's carbine 308 buffers weigh 3.8 oz (for various reasons). Many builders use a buffer weight of around 5.5 oz. The heavier weight helps with "bolt bounce" and slows the action down, which I believe is the source of your problem. I've used Kaw Valley Precision 308 buffers (5.6 oz) in the past. Slash's Heavy Buffers is another source and has a lot of info at their site and will help you if needed. There are some downsides to using a heavy buffer, specifically a higher rate of broken bolt catches (especially early Aero's), so pay attention to the distance between the bolt face and the bolt catch at max pull of the CH.
Another way to tune the rifle is by changing the action spring. Check out David Tubb's website, he has a lot of info and a lot of people swear by the Tubb's Flatwire Spring. Sprinco also is a reputable source.
One last thing is concerning the gas system. My personal experience with the Aero 18" using rifle length gas is they port it out at 0.089". If you remove the gas block again, it would be helpful if you measure your gas port, typically done with pin gauges but numbered drill bits work .I believe that the 0.089" gas port is about right. I do run adjustable gas blocks on a couple builds, but my intent is not to unless running suppressed and unsuppressed on the same rifle There are a number of other ways to tune the gas system other than AGB's.
I just about think I'd died and gone to heaven it I found out you were my neighbor. Your advise is thoughtful, chock full of content and you can just feel the wisdom of your words which tells me this is because you have lived, experienced and taught this stuff for quite some time. I wish I could tell you how grateful I am to have your time in attending my problems. I'm learning not only my problem but how to become enriched in so many related items. I just love the building and learning. No one here to teach. But that's been the story of my life. If one man did it, I believe I can. In my little pond, I'm the guy folks go to for help. But there's so much more. Casting, how to mount a scope and zero it two to three shots. How to hold and shoot. Etc. Then there's time like this where I just need a little bit more. I've had other responses that often will not only make no sense but be condescending. Anyway, thanks for being here. When I do get this, and I will, I will happily relay to the owner were credit is due. The new spring and weight arrived yesterday. The range is an hour and My Wife will want to practice with something. So when the weather gets a bit nicer I'll get a report in. Thanks buddy!
 

Goodknight

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Solid advice.
The Armalite AR10 carbine receiver extension, which used to be called "intermediate length", is the same inside depth (7 5/8" - 7 3/4") as a Vltor A5. The compete Armalite package (RE, buffer and spring) is compatible with the DPMS pattern rifles, and is usually sold at the Armalite website for a decent price, but I have no idea about current price and availability.
Standard carbine RE's have a depth of 7", which require the use of a short buffer (2.5") when used in the 308 platform. Aero's carbine 308 buffers weigh 3.8 oz (for various reasons). Many builders use a buffer weight of around 5.5 oz. The heavier weight helps with "bolt bounce" and slows the action down, which I believe is the source of your problem. I've used Kaw Valley Precision 308 buffers (5.6 oz) in the past. Slash's Heavy Buffers is another source and has a lot of info at their site and will help you if needed. There are some downsides to using a heavy buffer, specifically a higher rate of broken bolt catches (especially early Aero's), so pay attention to the distance between the bolt face and the bolt catch at max pull of the CH.
Another way to tune the rifle is by changing the action spring. Check out David Tubb's website, he has a lot of info and a lot of people swear by the Tubb's Flatwire Spring. Sprinco also is a reputable source.
One last thing is concerning the gas system. My personal experience with the Aero 18" using rifle length gas is they port it out at 0.089". If you remove the gas block again, it would be helpful if you measure your gas port, typically done with pin gauges but numbered drill bits work .I believe that the 0.089" gas port is about right. I do run adjustable gas blocks on a couple builds, but my intent is not to unless running suppressed and unsuppressed on the same rifle There are a number of other ways to tune the gas system other than AGB's.
Again, solid advice!! You give me knowledge and resources. I'll keep you posted on my progress. Good excuse to buy a set of pin gauges or quality set of numbered drill bits. Thank you!
 
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Again, solid advice!! You give me knowledge and resources. I'll keep you posted on my progress. Good excuse to buy a set of pin gauges or quality set of numbered drill bits. Thank you!

If you're going to buy a tool, buy the right tool for the job and get a pin gage set, drill bits may get you in the neighborhood but you're talking about hundredth and thousandths of an inch it is a pretty tight neighborhood.
 
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