Question about AR pistols

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MistWolf said:
Low shelf. That lower is actually their M4 lower.

Here is the link for their Stealth lower-
https://palmettostatearmory.com/psa-stealth-lower.html
Click to expand...

I checked that one out too. I’m seriously looking at the Aero M4E1 as well. It has some interesting features. I just can’t decide if I like the fact that the trigger guard is a part of the lower. Anyway, I’ve narrowed it down to 3. The PSA, the Aero M4E1 or the Aero Gen 2. The gen 2 has the features I’m most interested in and it doesn’t have the built in trigger guard, although it doesn’t have the low shelf.

I think I’m leaning toward one if the Aeros. I like the features and although the PSA has the low shelf, I don’t know that that’s important enough to base my decision on. I’d like to have the option, but really, even when shooting a full auto, the entertainment value wore off quickly and I usually just use the select fire position anyway.

I really appreciate the help.
 
The low shelf only matters if you want to try a Binary or Echo trigger (fires when pressed and again on release). They're a lot of fun, but expensive.
 
MistWolf said:
The AR Tony has put together is a 5.56 and there is no need to play around with buffer weights. What works is known- H, H2, A5H2 and Rifle, depending on which RE is used. Gas port diameters are also known. If the gas port is too large or too small, changing the buffer won't fix it. If a buffer lighter than H or heavier than A5H2/Rifle is needed to fix ejection angle, the AR has other problems.

If the AR is in spec- Colt or Sprinco M4 extractor spring, good ejector, proper gas port, proper action spring, proper buffer and in spec ammo is used, ejection angle becomes a moot point.

I suspect it's much the same for the 300, but I haven't tested ARs in that caliber.
Click to expand...
I built an AR 556 with a Daniel Defense barrel and BCG. DD barrels are classically overgassed via port size. Threw brass consistently at one o'clock, an H2 buffer solved the problem. Of all the rigs I have made in various calibers, finding the right buffer, and each rifle is different, has taken care of timing issues. Never needed an adjustable gas block, though I have built one with one, and it has detent adjustments.
 
Waiting in the wings is AR #9 which will be using the M4E1 upper/lower combo. I have RRA, PSA, lots of Anderson’s, and an Aero Gen 2. Looking over the M4E1 lower, I’ve not seen another forged that I like as much. At some point I’ll pick out a billet set that speaks to me despite the price tag, but at present the Aero is my “higher” end.

I slipped a standard MOE grip on and the trigger guard wasn’t my least favorite, overall it was more than useable. Unless you’re truly wed to a specific trigger guard or actually unhinge for gloved shooting I think the closed guard is adequate.

The threaded bolt catch pin is the real feature I’m excited to see. As I’ve played around with numerous styles and continue finding parts I deem better, swapping out old ones should be a piece of cake.


The “other” receiver set I waited all weekend for with the second of 2 M4E1 Enhanced uppers. I didn’t intend to buy 2 sets but the back order notifications left me a bit bent. At any rate I’ll be able to get another kid started building.
FB243D0A-ECAA-49B9-BACE-B10175ED2105.jpeg
 
KYregular said:
I built an AR 556 with a Daniel Defense barrel and BCG. DD barrels are classically overgassed via port size. Threw brass consistently at one o'clock, an H2 buffer solved the problem. Of all the rigs I have made in various calibers, finding the right buffer, and each rifle is different, has taken care of timing issues. Never needed an adjustable gas block, though I have built one with one, and it has detent adjustments.
Click to expand...
A heavier buffer may have changed ejection angle, but it didn't solve the problem of over gassing.

Forward ejection angle is usually caused by a weak extractor spring. In your case, the faster carrier speeds have exposed that the extractor spring is border line. It's working good now, but you're extractor spring will start giving you problems. In my experience, your heavier buffer is a bandaid for two problems- over gassing and an out of spec extractor spring.

The H2 is the right buffer. But even with the under weight carbine buffer, ejection shouldn't be 1 o'clock. I suggest you replace the spring with a Colt or Sprinco M4 spring (no donut).

This is why I maintain that using ejection angle to figure out how an AR is gassed is useless.
 
MistWolf said:
A heavier buffer may have changed ejection angle, but it didn't solve the problem of over gassing.

Forward ejection angle is usually caused by a weak extractor spring. In your case, the faster carrier speeds have exposed that the extractor spring is border line. It's working good now, but you're extractor spring will start giving you problems. In my experience, your heavier buffer is a bandaid for two problems- over gassing and an out of spec extractor spring.

The H2 is the right buffer. But even with the under weight carbine buffer, ejection shouldn't be 1 o'clock. I suggest you replace the spring with a Colt or Sprinco M4 spring (no donut).

This is why I maintain that using ejection angle to figure out how an AR is gassed is useless.
Click to expand...

To be honest, I do use ejection angle and as indicator of the gas situation. I keep my bolt in tip top shape. I don't know of any brand names of springs and small parts, but I do get what I think are quality small parts (springs, pins, extractors, ejectors, etc.) from Bravo Company. I was always under the impression that if all things were running as they should be, the ejection pattern could be used to "read" whether a rifle/pistol is over gassed.
 
TonyAngel said:
To be honest, I do use ejection angle and as indicator of the gas situation. I keep my bolt in tip top shape. I don't know of any brand names of springs and small parts, but I do get what I think are quality small parts (springs, pins, extractors, ejectors, etc.) from Bravo Company. I was always under the impression that if all things were running as they should be, the ejection pattern could be used to "read" whether a rifle/pistol is over gassed.
Click to expand...
Before either of us knew any better, a friend of mine and I tried to tune one of his ARs with an adjustable gas block using the ejection pie chart. It was quite frustrating. On top of that, I felt stupid when I said "Setting the gas on a FAL is much easier. Just keep closing the gas port (FALs work by venting excess gas) until it ejects and locks back!" before the light bulb went off in my head. Tune an AR using the lock back check, not the pie chart.

With an adjustable gas block on an AR, close off the gas until it ejects, but does not lock back. Then, open the gas block until it ejects and locks back. Now the gas is set at the minimum gas needed for full function regardless of buffer weight. (For added insurance, open the gas another quarter turn/one click. I've never needed to.)

If the AR doesn't have an adjustable gas block, the only way to tell if it's over gassed is either to pull the gas block and measure the gas port diameter, or through experience with how the recoil feels. If the recoil feels sharp (assuming the right buffer is installed i.e. H, H2 A5H2 or rifle along with an in spec spring) the AR is likely over gassed. However, if a carbine weight buffer is installed, recoil could be sharp even if properly gassed. If an AR has a carbine weight buffer and recoil feels sharp, it may not be over gassed. It may be under buffered. There is a difference.

As a Public Service Announcement, be aware that BCM released a bad batch of extractor springs. I recommend Colt springs because I have first hand experience with them. I recommend Sprinco springs because Will Larson of Semper Paratus recommends them and I trusted his experience and knowledge. (He passed away last summer.) I saw many BCM springs that needed to be replaced. I also saw many generic brand springs fail.

I don't know what angle my ARs eject at. Between them, I think they run from 2:30 to 4:30. I don't sweat it. I get the gas drive, buffer, spring and ammo right, use Colt extractor springs and always get 100% reliability.
 
MistWolf said:
Before either of us knew any better, a friend of mine and I tried to tune one of his ARs with an adjustable gas block using the ejection pie chart. It was quite frustrating. On top of that, I felt stupid when I said "Setting the gas on a FAL is much easier. Just keep closing the gas port (FALs work by venting excess gas) until it ejects and locks back!" before the light bulb went off in my head. Tune an AR using the lock back check, not the pie chart.

With an adjustable gas block on an AR, close off the gas until it ejects, but does not lock back. Then, open the gas block until it ejects and locks back. Now the gas is set at the minimum gas needed for full function regardless of buffer weight. (For added insurance, open the gas another quarter turn/one click. I've never needed to.)

If the AR doesn't have an adjustable gas block, the only way to tell if it's over gassed is either to pull the gas block and measure the gas port diameter, or through experience with how the recoil feels. If the recoil feels sharp (assuming the right buffer is installed i.e. H, H2 A5H2 or rifle along with an in spec spring) the AR is likely over gassed. However, if a carbine weight buffer is installed, recoil could be sharp even if properly gassed. If an AR has a carbine weight buffer and recoil feels sharp, it may not be over gassed. It may be under buffered. There is a difference.

As a Public Service Announcement, be aware that BCM released a bad batch of extractor springs. I recommend Colt springs because I have first hand experience with them. I recommend Sprinco springs because Will Larson of Semper Paratus recommends them and I trusted his experience and knowledge. (He passed away last summer.) I saw many BCM springs that needed to be replaced. I also saw many generic brand springs fail.

I don't know what angle my ARs eject at. Between them, I think they run from 2:30 to 4:30. I don't sweat it. I get the gas drive, buffer, spring and ammo right, use Colt extractor springs and always get 100% reliability.
Click to expand...

Oh, man. I did not know that about BCM's springs. Mine have been running right, or I think they have. I can't remember the last time I had a stoppage in either of my rifles and I now have coming around 1000 rounds through this pistol build. I did just swap out the carbon fiber lower for a Spike's that I had laying around. That thing with the safety emerged it's head again so I didn't play around with it. The carbon fiber lower is going into the .22 build when I get around to it.
 
When the ejector spring starts going, you'll see the ejection pattern start to move forward. Another indicator is bolt over base failure to feed and as it progresses, there will be stovepiping and spent cases caught in the action.
 
MistWolf said:
When the ejector spring starts going, you'll see the ejection pattern start to move forward. Another indicator is bolt over base failure to feed and as it progresses, there will be stovepiping and spent cases caught in the action.
Click to expand...

So, you like Springco? I need to order a few recoil springs anyway. I'll dump the springs I have from BCM and order more. I ordered a good stock of replacement stuff from BCM years ago. Any other parts I need to worry about? Gas rings?
 
Run your BCM springs but keep an eye on them. Replace them (just like any extractor spring) at the first sign of trouble.

Spares to keep your AR running-
- Extractor springs
- Hammer springs
- One complete bolt carrier group
- Action springs
- One complete trigger group
- Batteries as needed
- Two Magpul magazines

You'll want to expand your kit if start tinkering
 
MistWolf said:
A heavier buffer may have changed ejection angle, but it didn't solve the problem of over gassing.

Forward ejection angle is usually caused by a weak extractor spring. In your case, the faster carrier speeds have exposed that the extractor spring is border line. It's working good now, but you're extractor spring will start giving you problems. In my experience, your heavier buffer is a bandaid for two problems- over gassing and an out of spec extractor spring.

The H2 is the right buffer. But even with the under weight carbine buffer, ejection shouldn't be 1 o'clock. I suggest you replace the spring with a Colt or Sprinco M4 spring (no donut).

This is why I maintain that using ejection angle to figure out how an AR is gassed is useless.
Click to expand...
Then just about every factory gun had that weak spring. Most manufacturers gun are overgassed so they will run anything. Daniel Defense is know for this. This is a new build and the extractor is strong.
 
TonyAngel said:
To be honest, I do use ejection angle and as indicator of the gas situation. I keep my bolt in tip top shape. I don't know of any brand names of springs and small parts, but I do get what I think are quality small parts (springs, pins, extractors, ejectors, etc.) from Bravo Company. I was always under the impression that if all things were running as they should be, the ejection pattern could be used to "read" whether a rifle/pistol is over gassed.
Click to expand...
Correct, it's not about an ejector spring it's about timing.
 
KYregular said:
Correct, it's not about an ejector spring it's about timing.
Click to expand...
When you say it's not about the ejector spring, are you claiming weak ejection has nothing to do with ejection angle? If not, can you clarify what you are saying? If so, can you present evidence that supports your claim?

Quite frankly, my experience with troubleshooting and experimenting with ARs says how forceful ejection is significant to ejection angle.
 
My problem is that, although I don’t bathe my AR like as if it was my child, I do keep up with it. I regularly keep up with the bolt. I swap bolts and then when I get a chance, I replace all of the small parts and then it goes to backup status in the grip of my AR.

I assume that all is as it’s supposed to be.

What’s odd is that I often look at ejection angle to determine whether to go with a heavier buffer, but I don’t look at ejection angle when tuning a gas block for a suppressor.
 
MistWolf said:
When you say it's not about the ejector spring, are you claiming weak ejection has nothing to do with ejection angle? If not, can you clarify what you are saying? If so, can you present evidence that supports your claim?

Quite frankly, my experience with troubleshooting and experimenting with ARs says how forceful ejection is significant to ejection angle.
Click to expand...
So an LE6920 Colt should be fine? My son in law had a brand new one that was overgassed still with that Colt spring. Had minor ejector swipe. Heavier buffer and it was gone. You can't tell me that there's only one or two springs that make an AR run right. Sometimes a heavier spring and/or o-ring will fix the problem and sometimes not. Usually, when an AR is overgassed it is the gas port. Is not really a huge issue most of the time. Either put on an adjustable gas block (which I don't prefer) or go to a heavier buffer. Or, just shoot it the way it is and don't worry about it. All my rigs throw brass at 4 o'clock in a neat pile with no ejector swipe with a standard spring, and shoot with a great pulse. I guess what I'm saying then is it could be a weak ejection spring, which would certainly cause issues, but that is not always the issue, especially in brand new guns.
 
What I'm about to share with you, I've learned from research, corresponding with industry experts, first hand experience troubleshooting & repairing ARs, and from taking the Semper Paratus AR armorer's course taught by Will Larson. I hope it helps to further understanding.

KYregular said:
So an LE6920 Colt should be fine? My son in law had a brand new one that was overgassed still with that Colt spring. Had minor ejector swipe. Heavier buffer and it was gone.
Click to expand...
The 6920 isn't over-gassed. Trouble is, it combines a carbine gas system and an extra inch and a half of barrel with an H buffer. The H buffer is borderline too light. That's why Colt uses an H2 buffer in the M4A1.

There is a difference between an over-gassed AR and a buffer that's too light, but it's hard to tell the difference because both give similar syptoms. An AR that uses the right gas port with an under weight buffer will have a carrier speed that's a little high. It will unlock with a little more violence. Recoil will feel sharper. Switching the H buffer for an H2 will slow things down just enough to put operating speed right where it needs to be. Your son's 6920 wasn't over-gassed, it was under buffered. Installing the heavier buffer was the right move.

You can't tell me that there's only one or two springs that make an AR run right.
Click to expand...
There are six springs critical to AR function- action, ejector, extractor, trigger return, hammer & disconnector springs. The three I've seen needing replacing the most are the extractor spring, action spring and hammer springs. The one spring I've seen fail the most is the extractor spring. That's why I give them the most attention.

Sometimes a heavier spring and/or o-ring will fix the problem and sometimes not.
Click to expand...
The answer isn't a stronger spring. The answer is the right spring. In the case of the extractor spring, Colt had to increase the spring rate at least three times. Each time was in response to a change that resulted in increased carrier speed. The first time is when they switched to a more energetic powder in the ammo, the second was when the developed the M4 and the third time is when units used the M4 for high volume fire to break contact.

Crane responded to this issue by recommending the addition of an O ring. Colt responded by redesigning the extractor spring. The military refused to approve it because they didn't want to add another part to the supply chain. Finally, Colt got the military to approve the new spring because the O ring was only a temporary fix. O rings flatten, dry out and break apart. If not replaced in a timely manner, the crumbs will foul the extractor and need to be cleaned out.

The O ring is a temporary fix. Any extractor spring that needs an O ring to work properly needs to be replaced. An O ring used with a Colt or Sprinco M4 spring will place too much pressure on the extractor. Too much force will be needed to snap the extractor claw over the rim and accelerate wear.

...when an AR is overgassed it is the gas port...
Click to expand...
This is correct.

Either put on an adjustable gas block (which I don't prefer) or go to a heavier buffer.
Click to expand...
Heavier buffers will not fix over-gassing. Putting a heavy buffer in an over-gassed AR does nothing more than mitigate the symptoms. Over-gassing must be fixed by reducing the gas drive (smaller gas port, adjustable gas block, etc.)

...All my rigs throw brass at 4 o'clock in a neat pile with no ejector swipe with a standard spring...
Click to expand...
The Colt extractor spring is the standard. Colt uses nothing else in their ARs.

...I guess what I'm saying then is it could be a weak ejection spring, which would certainly cause issues, but that is not always the issue, especially in brand new guns.
Click to expand...
The extractor spring is what was bad in my brand new PSA. Some time back, we saw a spate of brand new BCM BCGs causing malfunctions caused by extractor springs. Some time after that, BCM quietly admitted they released a bad batch of extractor springs.

A good extractor & spring will not jump the case rim when carrier speeds increase. They will not lose control of the case during extraction. Violent carrier speeds with an in spec extractor & spring will bend or even rip the rim from the case.
 
MistWolf said:
What I'm about to share with you, I've learned from research, corresponding with industry experts, first hand experience troubleshooting & repairing ARs, and from taking the Semper Paratus AR armorer's course taught by Will Larson. I hope it helps to further understanding.


The 6920 isn't over-gassed. Trouble is, it combines a carbine gas system and an extra inch and a half of barrel with an H buffer. The H buffer is borderline too light. That's why Colt uses an H2 buffer in the M4A1.

There is a difference between an over-gassed AR and a buffer that's too light, but it's hard to tell the difference because both give similar syptoms. An AR that uses the right gas port with an under weight buffer will have a carrier speed that's a little high. It will unlock with a little more violence. Recoil will feel sharper. Switching the H buffer for an H2 will slow things down just enough to put operating speed right where it needs to be. Your son's 6920 wasn't over-gassed, it was under buffered. Installing the heavier buffer was the right move.


There are six springs critical to AR function- action, ejector, extractor, trigger return, hammer & disconnector springs. The three I've seen needing replacing the most are the extractor spring, action spring and hammer springs. The one spring I've seen fail the most is the extractor spring. That's why I give them the most attention.


The answer isn't a stronger spring. The answer is the right spring. In the case of the extractor spring, Colt had to increase the spring rate at least three times. Each time was in response to a change that resulted in increased carrier speed. The first time is when they switched to a more energetic powder in the ammo, the second was when the developed the M4 and the third time is when units used the M4 for high volume fire to break contact.

Crane responded to this issue by recommending the addition of an O ring. Colt responded by redesigning the extractor spring. The military refused to approve it because they didn't want to add another part to the supply chain. Finally, Colt got the military to approve the new spring because the O ring was only a temporary fix. O rings flatten, dry out and break apart. If not replaced in a timely manner, the crumbs will foul the extractor and need to be cleaned out.

The O ring is a temporary fix. Any extractor spring that needs an O ring to work properly needs to be replaced. An O ring used with a Colt or Sprinco M4 spring will place too much pressure on the extractor. Too much force will be needed to snap the extractor claw over the rim and accelerate wear.


This is correct.


Heavier buffers will not fix over-gassing. Putting a heavy buffer in an over-gassed AR does nothing more than mitigate the symptoms. Over-gassing must be fixed by reducing the gas drive (smaller gas port, adjustable gas block, etc.)


The Colt extractor spring is the standard. Colt uses nothing else in their ARs.


The extractor spring is what was bad in my brand new PSA. Some time back, we saw a spate of brand new BCM BCGs causing malfunctions caused by extractor springs. Some time after that, BCM quietly admitted they released a bad batch of extractor springs.

A good extractor & spring will not jump the case rim when carrier speeds increase. They will not lose control of the case during extraction. Violent carrier speeds with an in spec extractor & spring will bend or even rip the rim from the case.
Click to expand...

Very good points, all of my rigs that I own I built. All either run Daniel Defense, Odin Works, or Toolcraft BCGs, which seem the be fine. The Daniel Defense barrel has a large gas port, as does the Ballistic Advantage barrels I've used. Odin Works was just right. I always use a clamp on gas block secure with Rockset. With a clamp on you can easily cheat the barrels gas port back a few thou and reduce gas flow. Truth be know, most AR rifles from the factory are off in one way or another, probably to make them run any ammo you feed them. Most of the 223 and 5.56 range brass that I pick up has at least some extractor marking or swipe on them, or nicked rims. This is the reason I build my own, because I know what components work well together. I have the proper tools and know-how, and I check head space on EVERY build before firing, the right way by removing the extractor and the ejector.
 
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