AR Sponsor
Posted: 11/29/2025 4:44:28 PM EDT
[Last Edit: zimm17][Edited]
|
I took my new Aero M5 build to the range today. Both with no muzzle device and with a Area 419 break on it, it didn't cycle far enough to pick up a new round. I had to manually cycle the bolt after each shot. I threw on a suppressor and it ran 100%. UPS just dropped off the Superlative Arms adjustable gas block that I thought I would need. I haven't installed it yet. But I was thinking it should be cycling with a standard gas block. I'm running an AR10 308 buffer and Wilson buffer spring with a standard AR15 commercial buffer tube. Wilson says it's 5% stiffer than Mil-spec- maybe that's the issue? https://www.midwayusa.com/product/1025169693 I'm running a standard Stoner 308 buffer: https://www.midwayusa.com/product/1018146083 I'm reading some conflicting into that AR10 and AR15 carbine buffers are different. Other articles say the AR15 tube works with the shorter buffer I have. Or maybe it just needs more than 40 rounds? That's what I shot through it today. |
Joined:
May 2022
Posts:
196
EE: 100% (121)
USA
|
Originally Posted By Jake1989: This is just typical aero qc. Another user was complaining that one of his two builds was kicking like a 12 gauge with the only difference being one had a criterion and another one had a ballistic advantage/aero barrel. What's the fix? If it's working suppressed, is it just under gassed? I'm reading about folks with Aero M5's needing to upsize the gas port hole. If that's the answer, I can do that and then put the adjustable gas block on in case the bigger hole is too big? |
Joined:
May 2022
Posts:
197
EE: 100% (121)
USA
| That sounds right, you could drill the hole bigger and adjust it with the AGB, but there is a chance you could end up overdoing it and having an offspec gas port if you are note experienced. If it were me I would either return it and get a more reputable brand or have it RMA'd. Getting a barrel to work as intended should be the responsibility of the company not the consumer. |
|
Yeah good call. I'll try the new adj gas block and get some more rounds down range. I'm reading about lots of folks who "fixed" their M5's by drilling the hole out to .089 (stock) or even up to .096. I won't drill until I test some other stuff. Since it's working just fine with the suppressor on it, I think it must be under gassed right now. RIght? |
|
I'm shocked by all the wrong answers. The problem is that the buffer you are using is too light. The "standard" 308 buffer weight is much heavier than your "H" carbine equivalent. Most people (myself included) use an H3. What's happening is that your too-light buffer / BCG system is unlocking too early, and the majority of the gas is then venting to the atmosphere. By adding the suppressor, you're increasing the amount of time the pressure is acting on the system and compensating for the too short dwell time. I've had this same exact phenomenon happen on lightweight BCG builds in both 5.56 and 300 BLK. Use a heavier buffer. If you keep doing what you're doing, you'll see that the edges of your bolt start to wear unevenly (on the side that rubs the extension during unlocking). It's very similar to an "over gassed" setup that also unlocks too early. |
|
Originally Posted By Deimo5: I'm shocked by all the wrong answers. The problem is that the buffer you are using is too light. The "standard" 308 buffer weight is much heavier than your "H" carbine equivalent. Most people (myself included) use an H3. . I'm running the standard 308 buffer weight. See the link above. I'm not using an AR15 buffer weight- those I read are too long to use with AR carbine tube I'm running. |
|
Originally Posted By zimm17: I'm running the standard 308 buffer weight. See the link above. I'm not using an AR15 buffer weight- those I read are too long to use with AR carbine tube I'm running. Your link says your buffer is 3.5oz, which is less than a standard carbine H, which is 3.8oz. A rifle buffer is 5.2oz, so a lot of people use something like a carbine H3 which is 5.4oz |
|
Why not just switch your buffer when you decide no suppressor? .308’s act differently than their smaller brother. If it’s cycling ‘with’ the suppressor, I’d move on. Well, in my case anyway. It’s because of muzzle devices on my end. Dedicate it to suppressed only. Done. It works. If you do not want this, then you do seek agb. I have zero experience with BA barrels. I only know Criterion and Noveske barrels in .308 and 6.5 cm. But, what I’ve noticed, dedicated suppressed or not is least headache with these guns. If you want to flip vs versa, agb all day. Add: I used a rifle speed on my last .308 build. I like it. Mounted on a Noveske barrel I like space with hot surface  
|
|
I get it. I thought "H3" meant AR15 buffer. I didn't realize you can get an AR10 H3 buffer. That sucks I just spent $32 on this one. Maybe I should start there. Edit- from the last comment about switching buffers. Interesting. I'll try a heavy buffer and see it if works with the break. I know the current set up works with the suppressor. Edit 2 - Just ordered a KAW 5.6oz H5 AR10 tugsten buffer. I'll give that a go. If that works, it would be easier to just swap buffers if shooting suppressed or not vs mucking with an ADJ gas block. |
|
Originally Posted By zimm17: I get it. I thought "H3" meant AR15 buffer. I didn't realize you can get an AR10 H3 buffer. That sucks I just spent $32 on this one. Maybe I should start there. Edit- from the last comment about switching buffers. Interesting. I'll try a heavy buffer and see it if works with the break. I know the current set up works with the suppressor. Edit 2 - Just ordered a KAW 5.6oz H5 AR10 tugsten buffer. I'll give that a go. If that works, it would be easier to just swap buffers if shooting suppressed or not vs mucking with an ADJ gas block. Yes it would. But if you get that superlative, just use it. Done. I put one of those on one of my other .308’s. If I choose again superlative vs rifle speed, rifle speed all day. Add: only for .30 caliber These things on 5.56, I look back. Nope. The M4A1 will run suppressed or not, without a agb. It doesn’t care, no adjustments needed. .308 is not same though. |
|
I was going to get the rifle speed, but I read they don't quite fit under the Aero handguard without some dremel tooling. I got the superlative today. I was thinking the AR10 would be slamming hard with the suppressor so I'd want to gas it down. But as is, it ran perfect and the brass was in a nice little area at 3:30. Here's my 13 year old trying it out: 
|
|
Originally Posted By zimm17: I was going to get the rifle speed, but I read they don't quite fit under the Aero handguard without some dremel tooling. I got the superlative today. I was thinking the AR10 would be slamming hard with the suppressor so I'd want to gas it down. But as is, it ran perfect and the brass was in a nice little area at 3:30. Here's my 13 year old trying it out: https://i.imgur.com/EBESbLz.jpeg Be happy! Dedicate it suppressed. Done. Do your own build and you already have the agb! |
|
Originally Posted By zimm17: I get it. I thought "H3" meant AR15 buffer. I didn't realize you can get an AR10 H3 buffer. That sucks I just spent $32 on this one. Maybe I should start there. Edit- from the last comment about switching buffers. Interesting. I'll try a heavy buffer and see it if works with the break. I know the current set up works with the suppressor. Edit 2 - Just ordered a KAW 5.6oz H5 AR10 tugsten buffer. I'll give that a go. If that works, it would be easier to just swap buffers if shooting suppressed or not vs mucking with an ADJ gas block. Yep. LFAR’s are different animals for sure |
|
Originally Posted By Deimo5: I'm shocked by all the wrong answers. The problem is that the buffer you are using is too light. The "standard" 308 buffer weight is much heavier than your "H" carbine equivalent. Most people (myself included) use an H3. What's happening is that your too-light buffer / BCG system is unlocking too early, and the majority of the gas is then venting to the atmosphere. By adding the suppressor, you're increasing the amount of time the pressure is acting on the system and compensating for the too short dwell time. I've had this same exact phenomenon happen on lightweight BCG builds in both 5.56 and 300 BLK. Use a heavier buffer. If you keep doing what you're doing, you'll see that the edges of your bolt start to wear unevenly (on the side that rubs the extension during unlocking). It's very similar to an "over gassed" setup that also unlocks too early. A buffer weight change isn’t going to make that drastic of a change. It’s gas volume, not buffer weight that’s his issue, I can almost guarantee it. |
|
Originally Posted By TobyLazur: A buffer weight change isn’t going to make that drastic of a change. It’s gas volume, not buffer weight that’s his issue, I can almost guarantee it. I agree. Every time one of these threads pop up folks toss in all kinds of stuff that might or might nit help, some recommendations are just down right wrong and/or stupid. As someone who has assembled over a dozen AR10 type rifles (.308, 7mm-08, .243, .338 Federal, and .358 Win) with minimal issues, ALL my rifles function as intended both suppressed and unsuppressed, I have the following thoughts: First off, nothing wrong with the Aero M5 as a base platform. When I built my rifles I stuck to the basics concerning manufacture and core parts (upper, lower, BCG, FCG, buffers, and springs. I've never used any of the other fancy BCG's, buffers, or springs or mixed parts concerning the core rifle. In fact, I ran my own training company for 14 years and the rifles (AR15's) that generally had issues were ones with fancy BCG's, triggers, and springs. Second, gas is limited as we all know by the barrel's gas port size, every gas block out there (that I've ever seen) is oversized which gives some MINOR room for error when aligning. That's not to dismiss the importance of getting it properly aligned, it's to point out adding an adjustable gas block will do nothing to increase gas volume. If it were my rifle, I'd double check the GB alignment, double check the BCG gas key, and use a standard weight .308 buffer and spring. All of this provides a basic basis from which to trouble shoot. If after all this, and you're using quality ammo with 150gr plus projectile, then odds are extremely high the barrel's gas port is either undersized or has a burr/obstruction ever so slightly that firing hasn't removed. Since you have the ADJ GB, if the next step IMO is to open the barrel's gas port, you can certainly do so quite easily. Get an assortment of drill bits and use one that just will go in the hole, use this to clean out the hole and re-fire the rifle. If no joy, increase the drill bit size as minimal as you can (buy/source a bit discernibly larger) and repeat the process. I've opened gas ports intentionally to 0.100" right off the bat for use with an adj GB as well as the ability to control gas volume when using bullets at both ends of the weight range for the specific cartridge, especially important for .308 and .243 as bullet weights for those have a wide range and greatly effect function. I've ordered barrels that offered the same gas port size option for the reasons already stated. Get a wooden dowel rod from Wal-Mart (arts-crafts section) to insert into the barrel to avoid over drilling. Tape a witness mark on the drill bit as a visual guide for drill depth. It's easy, can be done with a hand drill, and the existing hole acts really well as a guide because you're not removing much material. Good luck, I'm sure you will get it up and running. |
|
Thanks. I cleaned it today and pulled the gas block. Looks fine to me. I did order a set of numbered drill bits so I can measure the diameter of the port and possibly upsize. Right now it's between a 5/64 and 3/32 drill bit- that's all I have on hand. If I do end up drilling the port- I have a drill press with a travel stop, so I can keep it from going too far. Wood dowel is a good safeguard too. I did order a H3 heavy buffer just to see if that makes a difference. I'll also get a GI spec spring as maybe the wilson at 5% stiffer might be just a hair too stiff. It's got to be close as is- it ejects great, but doesn't pick up the next round unless the suppressor is on. I'm holding off on the adj gas block until more testing is done. |
|
Originally Posted By zimm17: Thanks. I cleaned it today and pulled the gas block. Looks fine to me. I did order a set of numbered drill bits so I can measure the diameter of the port and possibly upsize. Right now it's between a 5/64 and 3/32 drill bit- that's all I have on hand. If I do end up drilling the port- I have a drill press with a travel stop, so I can keep it from going too far. Wood dowel is a good safeguard too. I did order a H3 heavy buffer just to see if that makes a difference. I'll also get a GI spec spring as maybe the wilson at 5% stiffer might be just a hair too stiff. It's got to be close as is- it ejects great, but doesn't pick up the next round unless the suppressor is on. I'm holding off on the adj gas block until more testing is done. What barrel? Length/Gas system? Ammo? |
|
Originally Posted By zimm17: Stock Aero M5 upper. 18" barrel with rifle length gas system. AAC .308 ball ammo. https://i.imgur.com/iWARRdd.jpeg Looks like your gas port is at least .078" if a 5/64 fits which IMO is on the small size. 3/32 will give you .094" which I am sure will work. I can tell you from first hand experience ammo A and ammo B can be the same bullet weight and velocity but won't act the same due to powder burn rate. I've loaded great ammo but the powder used doesn't play well so it's a wash. I'm not sold on ACC ammo... I'd hit the local fun shop or Wal-Mart and grab a box of 150-165gr bullets just to see if a different round produces results. Won't hurt to rule out ammo as a possible cause. |
Joined:
Sep 2022
Posts:
166
EE: 0% (0)
TX, USA
|
This has been an issue with BA/Aero M5 barrels for years at this point. I solved it by going with a lighter buffer weight. Alternatively, you can get a gunsmith to drill out the gas port and put an adjustable gas block on it. For the long-term solution, I sold off my Aero M5 to start a fund for buying something like a DD, Seekins, or possibly Larue AR-10 instead. |
|
I wanted to circle back on this and the issue is fixed. I drilled out the gas port to .089 and hit the range today. It ran perfect bare muzzle, with brake, and suppressed. I notice as I switched from brake to surpressor, the brass went from being thrown a 3 to 5 o'clock, which I assume is a symptom of more gas in the system. I bought an adjustable gas block, but I don't know if it's even worth putting on at this point. I don't plan to shoot this AR10 very much and I'd rather not fiddle with an adjustable gizmo if it works as is. |
|
As stated above, typical Aero QC. I put one together a couple years ago. The first upper I received would not accept any charging handle I owned. They replaced it. The replacement wouldn’t lock back on empty, and cases ejected 1-2 feet. I don’t remember the specs, but I measured the gas port at .019 smaller than it should have been. I just hand turned the correct bit through there. It runs great now, both suppressed and unsuppressed. ETA: Mine has a rifle gas 18” barrel with a rifle buffer. |
AR Sponsor