HELP! Aero M5 not running

[kingofthepoors]

Thanks again for all the help. I think the problem might be a dumb one. I thought it would be bad to shoot my rifle with the gas all the way or adjusted like that. I’m going to try that and the oiling of the bolt. I feel like that’s what it was honestly. I just had the gas way too low. The guy saying 1.5 turns for both his rifles made me think something was wrong for me having to have it all the way backed out. Is it ok to have the adjustment screw out or do I just barely have it in and use the set screw? Don’t want to lose any small parts or damage the gun. Sorry for my ignorance. First time DPMSer here

 

[bfoosh006]

Thanks again for all the help. I think the problem might be a dumb one. I thought it would be bad to shoot my rifle with the gas all the way or adjusted like that. I’m going to try that and the oiling of the bolt. I feel like that’s what it was honestly. I just had the gas way too low. The guy saying 1.5 turns for both his rifles made me think something was wrong for me having to have it all the way backed out. Is it ok to have the adjustment screw out or do I just barely have it in and use the set screw? Don’t want to lose any small parts or damage the gun. Sorry for my ignorance. First time DPMSer here

Dude... we all learned somehow and somewhere.

Point is , we are here to help you enjoy your firearm.

Not grind you into the dirt, and stalking you ... like elsewhere.

As for the JP gas block, follow the directions in the manual for a starting point, and watch the video


I am not a fan of screw adjustable GB's ... I much prefer click adjustable GB's.... why ? Quote "Don’t want to lose any small parts"

As for damaging your gun, remember a Adj GB cannot make gas flow anymore then your gas port allows.

If you have anymore questions, come back and ask.

Glad to hear you're gonna go burn money through that barrel... ( ammo that is.. )

Lets us know how it shoots.

 

[Mike_in_FL]

Your 1st step should be to adjust the gas to fire one round and lock back on an empty magazine. Give it a hair more for reliable function and THEN see if it will pick up new rounds from the mag.

Yes, you can lose the set screw on a JP AGB, ask me how I know or why I buy only SA now. That being said, there's a drawing of the AGB on JP's website with the correct pitch should you lose yours so you can buy a new one at the hardware store. Guess what happens if the screw does fall out? You have a one shot rifle just like now.

I don't know who 1 1/2 turns out guy is but you should've asked if he had a mid-length or rifle length gas system. A middy is always pushing more gas into the system so less on his adjustment would make sense. Also, realize that whenever you change ammo you're going to have to readjust your gas setting.

If you have the heavy profile BA barrel, then I have the same. It's the softest shooting .308 gasser I've put together and still just using an A2 FH.

 

[kingofthepoors]

Dude... we all learned somehow and somewhere.

Point is , we are here to help you enjoy your firearm.

Not grind you into the dirt, and stalking you ... like elsewhere.

As for the JP gas block, follow the directions in the manual for a starting point, and watch the video


I am not a fan of screw adjustable GB's ... I much prefer click adjustable GB's.... why ? Quote "Don’t want to lose any small parts"

As for damaging your gun, remember a Adj GB cannot make gas flow anymore then your gas port allows.

If you have anymore questions, come back and ask.

Glad to hear you're gonna go burn money through that barrel... ( ammo that is.. )

Lets us know how it shoots.

Yeah I was banned from another unnamed forum...
I’m excited because I think that was the problem as stupid as that is.

 

[kingofthepoors]

This is the post he made on a post I made on Reddit in reference to the fiasco that my post on ar10 forum became.

 

[loveha]

Like mentioned, having your gas block open all the way is not going to hurt a thing. The last rifle I built I didn't bother with an adj. block as it is a point of failure. It runs great suppressed and unsupressed with my buffer and spring choice.

Some barrel makers over size their gas ports for "reliability reasons" because they don't know the buffer/spring/ammo that will be used.
Some don't, and are made with more appropriate port sizes. So having to open the gas block all the way could also be a sign your gas port isn't oversized.
Having an over gassed gun will only beat you up, and maybe the rubber bumper on the buffer.

Oil works, but a thin grease lasts longer.
If you go with grease here is an article on where to grease. (They also sell several, and all I use.)

How to Lube an AR for Maximum Reliability

There's no voodoo here - when lubricating an AR or any gun, this is your universal rule: Learn to examine your guns in terms of "friction surfaces" - when this becomes habit, guns reveal nearly all of their operational and reliability secrets, and it tells you exactly where to lube, even on...

www.cherrybalmz.com

 

[bfoosh006]

This is the post he made on a post I made on Reddit in reference to the fiasco that my post on ar10 forum became.

Ehhh... some people. Life is to short to try and change some people.

Let us know how it shoots

 

[Caterpillardoc]

Is your rifle running now? If not, what ammo are you using? Have you tried more than one load?


I would try loads in the 147-168 grain range. You may find your rifle runs well with some, not so good with others.

 

[wigwamitus]

I got an M5 (all stock parts from AP) about 6 weeks ago ... 20 inch barrel ... rifle length gas tube ... no AGB ... didn't think I'd need one ... I put a carbine buffer tube, spring etc. on mine ... I got the AP M5 "carbine" rear end ... included tube, spring and buffer. It worked fine for 175gr FGMM both suppressed and unsuppressed ... but did not work for LC M80 '18 either with or without suppressor. I replaced the spring with a "light" spring ... and then everything worked fine. YMMV.

I do have the "nitride" BCG on there ... so even though the buffer assembly was "made" for this rifle ... the combo of the heavier BCG and the "light load" M80 LC '18 ammo (??) must have tripped across the under-gassed line ... the lighter spring fixed it.

 

[Caterpillardoc]

I got an M5 (all stock parts from AP) about 6 weeks ago ... 20 inch barrel ... rifle length gas tube ... no AGB ... didn't think I'd need one ... I put a carbine buffer tube, spring etc. on mine ... I got the AP M5 "carbine" rear end ... included tube, spring and buffer. It worked fine for 175gr FGMM both suppressed and unsuppressed ... but did not work for LC M80 '18 either with or without suppressor. I replaced the spring with a "light" spring ... and then everything worked fine. YMMV.

I do have the "nitride" BCG on there ... so even though the buffer assembly was "made" for this rifle ... the combo of the heavier BCG and the "light load" M80 LC '18 ammo (??) must have tripped across the under-gassed line ... the lighter spring fixed it.

I’ve found AR 308’s not as “Leggo” friendly as the AR15 platform. I have 2 Aero AR308’s, an 18” .308 and a 22” 6.5 Creedmoor.

I had to work getting to .308 running with a mixed bag of parts. Once I gave up and used all Aero parts it’s running fine.

For the 6.5 Creedmoor I originally used a bolt carrier group with the standard firing pin and had trouble with pierced primers. I learned later you have to use a high pressure bolt and it has run great since swapping it out.

Both rifles are very accurate with target bullets.

 

[kingofthepoors]

Guys it ran!!!!!!!!! It was as I expected, the gas was just way too low. I’m super excited right now. I took my formerly anti gun parents to the range today to break in the new pistol I got for them. I brought along my aero just to function check it and it ran. I fired four or five rounds and it ran! Now to zero it in in the next day or two and I’ll post the the group. Again thank you to everyone who tried to help with this mystery. It turns out I was just a dumbass and had the gas way too low and the old non adjustable gas block was misaligned. Got an adjustable and a bore scope and were in business.

 

[357Max]

Thanks for posting the follow up. Glad to hear it runs well now!

 

[kingofthepoors]

So I went back to zero the rifle today. Good news and bad news. The good news is the rifle cycles now and is accurate. The bad news is it only cycles when I stand and shoot. It will eject a round on the bench but never picks up a new one. This is a heavy ass bench rifle so this is no bueno. Anyone know what that could be? I’ve never heard of this happening.

 

[loveha]

When you got it to cycle, did you just go ahead and open the gas up all the way? Or is there still room to adjust the gas block?

 

[kingofthepoors]

I got it opened up maybe 3/4 or 4/5 the way. I’m just wary of losing the screw. Seems like kind of a dumb system. I might just open up the gas port on the barrel slightly so I don’t have to have it opened up all the way. When it shot earlier today I was standing as it was on the 25 yard “pistol” range. When I came back later I was sitting at the bench at the 100 yard range. It would eject but not pick up a round. So I opened it up twice. It wouldn’t cycle correctly still so I figured I’d try standing up ass that was the only time it’s cycled ever. To my surprise it would cycle every time standing and only eject at the bench. The range officer was stumped too.

 

[corey4]

Opening the gas block all the way won't allow more gas flow that what your gas port is drilled.

Were you giving enough resistance to the recoil on the bench? Kinda like limp wristing a pistol? Is that even possible on an AR?

 

[kingofthepoors]

I’m saying I want to drill out the gas port a little so I don’t have to have the gas block opened up so much. I’m worried about losing the screw. And as far as limp wristing on the bench I’ve never had that problem with any of my other rifles so I’m not sure. It seems like I was more locked in on the bench and my body have much more when standing.

 

[kingofthepoors]

Will a H2 buffer work with my set up? I have a rifle gas system and a rifle stock not a carbine. I figured the H2 buffer is for carbine tube/stocks? Someone else had mentioned I get the H2 but when I asked this question they never responded

 

[kingofthepoors]

I dont have a scale but the websites specs list my buffer weights at 5.3oz and 11.2oz for the unit.

That’s actually heavier than an H2 correct? It says H2 weight is like 4.7ish?

 

[357Max]

No! Do not use an H2 carbine buffer in your rifle buffer system. Your BCG will crash into the lower if you try it.
I think sometimes people confuse rifle gas with rifle buffer and interchange them.

Did you ever measure the gas port size in the barrel?

 

[kingofthepoors]

No! Do not use an H2 carbine buffer in your rifle buffer system. Your BCG will crash into the lower if you try it.
I think sometimes people confuse rifle gas with rifle buffer and interchange them.

Did you ever measure the gas port size in the barrel?

Thanks brother. This is what I thought. Saved me a few dollars. I haven’t measured the gas port size as I was hoping to not have to. I got everything lined up perfect and torqued/loctite. I will probably do that soon though just to check off the list. At the very least maybe reach out to ballistic advantage and ask them as they were really fast and very helpful with my previous question to them. I’m thinking if I just open it up a tad then I wouldn’t have to have my block opened up so much. The real thing that is strange to me is how the gun runs standing up but only short strokes at the bench.

 

[Powder_Burns]

Just remember its a lot easier to remove metal than to replace it. Opening the gas port should be a last resort.

 

[loveha]

Only thing I could think of is if there is to much play between the receivers you could be somehow binding the BCG when you are pushing on it at the bench. Find that idea unlikely though.

 

[357Max]

The fact that it runs one way and not the other just tells me it's on the edge of working properly.

The 5.3oz buffer you have is the std for AR 308, however BA may have drilled the port on the small side for all the guys running 7.75 length 308 buffer tubes and using H2 (4.6oz 3.25" buffers).

Before you get any further down the rabbit whole.........Crank that Adj JP wide open & try it. See pic below for reference of how far out the set screw is when it's wide open. I'm not a fan of this JP adj gas block (big bulky & typically adjustment is behind rail), but I have one on a 300bo pictured.
Edit: As you can see I had to mill the damn rail just to get it adjusted full open.
I am a big fan of the SLR adj gas blocks & will continue using them.

If the above doesn't work.
I think you may be on the right track to drill the port if it's on the small side i.e. under .089
AR 308's really should have a buffer weight pretty close to or greater then what you've got already so I would not recommend a lighter one.

 

[kingofthepoors]

Yeah I’m hoping to fix the rifles problems without having to permanently modify it. And the recievers are both aero are kind of tight honestly so I’m not sure if that could be the issue. The screw that tightens the upper and lower that’s under the rear takedown pin is low where it’s not really doing anything. Should I tinker with that?

 

[loveha]

If the receivers are already snug, it's not important. Won't hurt though, and probably won't fix anything. Those tension pins are just a luxury IMO.

 

[fdkay]

So I went back to zero the rifle today. Good news and bad news. The good news is the rifle cycles now and is accurate. The bad news is it only cycles when I stand and shoot. It will eject a round on the bench but never picks up a new one. This is a heavy ass bench rifle so this is no bueno. Anyone know what that could be? I’ve never heard of this happening.

Don't rest the rifle on the magazine.

 

[1500varmint]

" *The ammo I was using was Winchester Super X 180gr & Federal Power Shok 180 gr. "

Is it possible that the ammo is part of the issue?

Have you tried anything other than the 180gr loads?

(I'm JUST about to start an Aero AR-10 build, so the timing of this thread is perfect)

 

[smoothy8500]

Could be that bench resting, the rifle isn't tight in the shoulder like you would hold it off-hand/standing?

My recent Aero M5 build is pretty similar: Criterion 20" 308 barrel, A2 buttstock, and adj gas block. I have about 1.5 turns open on the gas screw (Odin works).

 

[padom]

The bench is not the problem. Open the gas block more, thats what its made for. Buy some different ammo to test in your AR properly. FGMM, Black Hills, M118LR, 147gr Ball, etc.... Not that 180gr 308 hunting ammo.....

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[Mike_in_FL]

So I went back to zero the rifle today. Good news and bad news. The good news is the rifle cycles now and is accurate. The bad news is it only cycles when I stand and shoot. It will eject a round on the bench but never picks up a new one. This is a heavy ass bench rifle so this is no bueno. Anyone know what that could be? I’ve never heard of this happening.

Dude. Put the rifle on the bench, one round in magazine, load into chamber, fire. Does it lock back on empty mag? THIS IS STEP ONE. Why do you keep trying to skip ahead?

If it doesn't lock back, give it more gas. When it locks back, give it a little more for reliability. Crawl before you start running marathons.

 

[shooter65]

Dude. Put the rifle on the bench, one round in magazine, load into chamber, fire. Does it lock back on empty mag? THIS IS STEP ONE. Why do you keep trying to skip ahead?

If it doesn't lock back, give it more gas. When it locks back, give it a little more for reliability. Crawl before you start running marathons.

This. Period.

 

[Caterpillardoc]

Finding what works would be less complicated if you fully open the gas block and find a load that operates in your rifle. Aero AR 308’s are designed to work with 165-168 grain bullets. Find something that works, then start dialing the gas block in. Mike in Fl is giving you good advise.

 

[8up]

Page 2 of open that gas block up.

 

[troupe]

Grease your buffer, spring and the inside of the tube. Also make sure the plunger is not dragging and your buffer tube is square with the rifle.

 

[kingofthepoors]

When I say it doesnt work on the bench Im not saying I rest the rifle on the mag. Im not sure where you got that idea? I have a bipod...

I cant really open it up much more without the adjustment screw falling out. I actually took your advice bro. Its really annoying messing with the gas setting as it sits perfectly behind the rail so that I have to remove the rail every time I adjust it. I think the trying other types of ammo might be it. I have only tried 180gr so far as it was the cheapest of what I have. I have 3 different Australian Outback loads and recently got a bunch of the steel case 308 for shits and gigs. I might buy another gas block to avoid modding the port. It needs to be a clamp on as they dimpled my barrel terribly off. Were close boys! The real question that I dont think anyone knows the answer to is why it only cycles when firing standing. When Im on the bench I feel like Im actually holding it tighter than standing. I do appreciate all the help and do take most suggestions. Ive got it opened up about as much as itll go and it seems like the port is just too small for this gas block and buffer set up. Im not sure how much more I can go out without losing the adjustment screw.

*edit* when I first got into guns I was an AK guy. They have always ran flawless. Ive literally never had any problems and that was running steel only. Then I got into ARs. They also always ran and have never given me any problems. I almost never clean or lube them either lol. I took a big leap to come to the bigger boy ARs and its just been one problem after another. I def appreciate the input and help. Dont give up on me yet!

 

[kingofthepoors]

Dude. Put the rifle on the bench, one round in magazine, load into chamber, fire. Does it lock back on empty mag? THIS IS STEP ONE. Why do you keep trying to skip ahead?

If it doesn't lock back, give it more gas. When it locks back, give it a little more for reliability. Crawl before you start running marathons.

My bad brah I thought I had already explained that in did in fact lock back. It was running perfectly while I was standing. Shot 4-5 rounds and cycled and locked back. For some reason it wasnt liking being on the bench. Im going to try the lighter grain ammo and will get back. It just seemed strange to me it would run one way and not the other.
As far as taking it to a smith does anyone know any good places around Tampa? Mike Im looking at you. The place I took it to that butchered my dimples and torque the barrel nut way too loose is out of the question. I asked a friend where he takes his stuff and when I called the dude said he was booked up for three months.

 

[Not a Clue]

I've never seen that actual gas block, but is there no lock for that adjustment screw? On all my adjustables with screws, there is a locking screw and an adjustment screw. On my M5 setup, it's a set screw and another set screw in the same hole for adjustment. You adjust it and run the screw up to the other one to lock it in. Other's have a screw from the side. If that screw is the only adjustment and there's no lock, that's a failure waiting to happen.

I'm sure you've looked at it enough to know, but there's not another screw in that hole, is it? (because that's how mine is setup)

 

[Mike_in_FL]

My bad brah I thought I had already explained that in did in fact lock back. It was running perfectly while I was standing. Shot 4-5 rounds and cycled and locked back. For some reason it wasnt liking being on the bench. Im going to try the lighter grain ammo and will get back. It just seemed strange to me it would run one way and not the other.
As far as taking it to a smith does anyone know any good places around Tampa? Mike Im looking at you. The place I took it to that butchered my dimples and torque the barrel nut way too loose is out of the question. I asked a friend where he takes his stuff and when I called the dude said he was booked up for three months.

I probably have everything you need at my house to fix it if you're this close to Pinellas. Something you can try quickly if you can get to a range is pull out your buffer and knock out the roll pin and remove a weight. Possibly the gas port is too small but I wouldn't be jumping to any conclusions and drilling on things. You need to decide at least what ammo you're actually going to always want to shoot and then it could be setup to run that 100%.

I can't recommend any smiths as I do everything myself. I do have a .750 dimpling jig as well.

 

[kingofthepoors]

I reached out to BA and they said that my barrel has a .089 gas port.
I’m in South Tampa/Downtown. I go out to Clearwater beach a few times a month so that might work out.

 

[Bolo]

QQ... by chance, is the handguard touching the GB when the bipod is loaded up? With a wonky GB, that could explain a lot...

 

[357Max]

FWIW - I think Mike is dead on with the recommendation to remove a weight from the buffer, but I wouldn't leave it as empty space....put something in there.

Per your picture I can see you've got that block wide open now. .089 gas port (if it is) with rifle length gas in a 20" barrel would be enough for a 5.3oz buffer.
I would check gas rings if you haven't already.

Just took my DPMS 308 to the range after complete rebuild and had a similar issue to yours. Had my original buffer system set up for mid gas 18" barrel with XH 8.5 oz buffer, with the new 18" rifle gas and SLR block wide open it was on the edge just like yours.
Pulled 2 of the 3 heavy (mallory metal) weights out and machined an aluminum replacement. It's now a 6 oz buffer and I swapped in a JP o.d. ground spring. We'll see how it runs on Sat.

 

[kingofthepoors]

So I haven’t taken it to the range lately. Honestly it’s too painful lol. Anyway I ordered an A2 buffer spring it and came today. They are the same length but the new one has more coils. I’m hoping that will be the fix. It’s much easier to pull the bolt back now. It says on the package compatible with most AR-15 calibers. Will this not work for my big boy AR-15? Also I noticed some marks on my buffer is that normal? Since this new spring makes the bolt pull back easier I think I’ll try adjusting the gas again.

 

[357Max]

I wouldn't put an AR 15 spring in there if it was mine. The spring you seek is here. http://heavybuffers.com/springs.html
This one. It is the Armalite spring & has a very good reputation for reliable function in large frames. If it won't run with that then something else is wrong.

The marks on your buffer are caused by an out of spec (if there is one) lower. You could contact Aero & show them that picture, but I wouldn't bother.
There is a fix and it's pretty cheap.
The buffer retainer detent is machined to far back. The buffer should be sticking out beyond the face of the receiver a little, like .030 when resting on the detent. When you close the rifle & look carefully as they come together, the back of bolt carrier should contact buffer just before closed and push it in (again about .030). What that does is to push the buffer away from the detent pin a little. The only time the buffer should contact the pin is when you break it open via take down pin. Yours is smacking the pin while running. Probably also causing a little bolt bounce.
This will fix you up for $18.00 shipped. https://gallowayprecision.com/offset-buffer-retainer-for-AR-15-rifles
There is a full explanation on there sight.