Overgassing in hot weather temperatures?

[MistWolf]

I don't think the extractor spring is failing, it's still throwing brass a good distance away, enough to annoy nearby shooters. I can check the spring too, but I don't think any part should be work out yet, I'm not yet at 1,500 rounds.

You don't think so? Let's take another look-

Something I'm noticing is that in the spring time and moderate weather, my gun eject at about 3 o'clock or so. However when it's summer and the temperature is in the 90s and my gun was sitting in the sun for a while, my ejection is now closer to 2 o'clock...

...when firing 5.56 ammo...his gun ejects at consistent 3 o’clock, while mine is 2 o’clock...

I’ll note that the stuff I stocked up and shoot isn’t anything special, just Wolf Gold M193.

...I'm not yet at 1,500 rounds.

If the extractor spring is working fine, there will be little to no change in ejection angle as the carrier speed changes. You'll note your body's upper consistently ejects at 3 o'clock while yours varies from 3 o'clock to 2 o'clock depending on temperature. In this case, as the temperature goes up, so does pressure. When pressure goes up, carrier speed increases. When the extractor spring begins failing, ejection angle moves forward. When carrier speed increases, greater stress is placed on the extractor spring. When greater stress is placed on an extractor spring that's failing, ejection angle moves forward.

The only two extractor springs with the durability and reliability in uppers with barrel lengths of 16" or less is first and foremost the Colt extractor spring. The second is the Spring 5 coil spring. The only company I'm aware of using Colt springs is Colt. The only company using Sprinco springs that I'm aware of is Sionics and SOLGW. The reason Sionics and SOLGW use the Spring is because they consulted with Will Larson (IraqGunz), a very knowledgeable and experienced armorer.

In my experience with troubleshooting ARs is that other extractor springs usually start failing between 750 to 1500 rounds. Your DD upper is coming up on 1500 rounds and is showing a variation in ejection angle.

Extractor spring tension impacts ejection angle. As the tension on the extractor drops, the case isn't held against the ejector as firmly. This changes how the case is ejected and how it bounces off the case deflector. The angle moves forward until cases start bouncing back inside the ejection port. Somewhere in the process, the extractor will slip the rim completely and empties will get caught in the action and the bolt will over ride the rim of the next case in the mag. Or, the empty will be ejected and the bolt will over ride the base.

In the beginning, the empties will still be ejected a good distance. Don't let that fool you.

When I took the armorer's class taught by Will Larson, I discussed this subject with him at length. His (far greater) experience supported mine.

Taking all of this into consideration, to address your sharper recoil, try a new action spring and see if that helps.

You can either order a new Colt or Sprinco extractor spring and install it when it comes in, or you can wait until you get intermittent malfunctions and waste a box or more of ammo trying to troubleshoot the issue.

[T2C]

Military M4’s, including brand new ones, will commonly yeet brass to the 2 o’ clock on a nice warm day, so that is indicative of….. nothing at all.

People mess with buffers entirely too much, in my opinion, and seem to expect that life changing results will occur with every .8 oz increment. Sometimes such a change is noticeable, sometimes it isn’t.

A log is a good thing to do. Ammo is, in fact, temp sensitive.

I am inclined to agree. If the carbine is accurate and reliable, I would not be too concerned.

Asking questions is good and there is nothing wrong with being aware of changes in recoil, muzzle blast, changes in POI due to sunlight, etc., that means you are paying attention.

I shoot M1 Garand's and 1903 Springfield's a few times a month, so that might make me less concerned about the recoil of a .223 caliber rifle than other people.

[Disciple]

The only two extractor springs with the durability and reliability in uppers with barrel lengths of 16" or less is first and foremost the Colt extractor spring. The second is the Spring 5 coil spring. The only company I'm aware of using Colt springs is Colt. The only company using Sprinco springs that I'm aware of is Sionics and SOLGW. The reason Sionics and SOLGW use the Spring is because they consulted with Will Larson (IraqGunz), a very knowledgeable and experienced armorer.

In my experience with troubleshooting ARs is that other extractor springs usually start failing between 750 to 1500 rounds. Your DD upper is coming up on 1500 rounds and is showing a variation in ejection angle.

Daniel Defense uses an o-ring and silver extractor spring in their bolts as of 2020. Some say this combination has a longer life than a stronger spring alone. I would like to believe there is a reason they sell their bolts with this combination other than mere greed. Nevertheless I have Colt copper-color springs on hand for spares.

It's generally accepted that carbines need more extractor tension than the original M16, and it's also generally accepted that the o-ring and extra power extractor together are usually too much.

We use a rifle extractor and O-ring on our rifles. We believe the O-ring has a longer service life than an extractor spring alone, while giving the increased extractor tension needed.

For a duty or defensive carbine it's also important to change the extractor spring based on a round count, not failure to extract.

And this cannot be over-stated. It is not that you don't "need" an extra-power spring if you have an o-ring, but extra-power springs are actually bad because they are more likely to break. So the way to think about it is that the o-ring saves you from having to resort to a high-stressed spring.

Once you have the o-ring to add tension, the goal should be to use the lowest-stressed spring, which should give the longest life.

I just measured every extractor spring Brownell's sells. I can say there is some scary stuff there.

The USGI spring from 1971 had a stress/strain ratio under 50% when compressed to 0.112. Those can last 18,000+ rounds. True, they only have 4 lbs of force at this height, but the o-ring will add in the extractor tension without having to resort to an extra power spring.

Why is an extra power spring bad? Because more force means more stress. Some of the springs from Brownell's had stress/strain ratios above 80%! If you monkey around with extra power springs, then change them every 1500 rounds.

The new M4 spring that is Copper colored is pretty interesting. It has exactly double the force of the earlier spring but does not have a huge amount of additional stress. If I were going to run a spring without an o-ring, I would use the new Colt M4 spring.

Or use an old-style 0.022 wire diameter USGI (people call this the '4 coil') with an o-ring and it should last the life of the bolt (but since it is cheap, might as well change it at 5000 rounds).

[MistWolf]

My research shows the O ring was adopted as an interim fix until the .mil could be convinced to approve the then new Colt extractor spring to the system, something the .mil resisted because it would “add a new NSN for the same part”. Until the upgraded spring was approved, they were stuck using the rifle extractor spring which was not strong enough for full auto in the M4 and prone to early failure.

Using an O ring introduces its own set of problems. O rings wear out, dry out and deteriorate. When the O ring starts deteriorating, the pieces impede extractor function.

Once institutional inertia was overcome and the upgraded Colt spring replaced the old spring, extraction issues in military M4s have been greatly reduced, if not eliminated. Over the years, I’ve only seen one Colt extractor spring prematurely fail and that was in one of my bolts. I suspect I damaged it during install

Bottom line- You can use the upgraded Colt spring which is proven to work. Or you can take your chances with the spring that made a redesigned spring necessary.

[Spooky1]

My research shows the O ring was adopted as an interim fix until the .mil could be convinced to approve the then new Colt extractor spring to the system, something the .mil resisted because it would “add a new NSN for the same part”. Until the upgraded spring was approved, they were stuck using the rifle extractor spring which was not strong enough for full auto in the M4 and prone to early failure.

Using an O ring introduces its own set of problems. O rings wear out, dry out and deteriorate. When the O ring starts deteriorating, the pieces impede extractor function.

Once institutional inertia was overcome and the upgraded Colt spring replaced the old spring, extraction issues in military M4s have been greatly reduced, if not eliminated. Over the years, I’ve only seen one Colt extractor spring prematurely fail and that was in one of my bolts. I suspect I damaged it during install

Bottom line- You can use the upgraded Colt spring which is proven to work. Or you can take your chances with the spring that made a redesigned spring necessary.

MistWolf I would like to ask you your opinion on the Colt Gold Extractor Springs compared to the 5 Coil Springco Extractor Springs, which do you think are the best? Or are they about equal?

Whenever I acquire a new AR or new to me AR, I will replace the Extractor Spring with a 5 Coil Springco and pitch the factory spring and O-ring in the trash. I will also put a new Ejector Spring in, it's a Sprinco also. I do have 2 Colts and they have the Colt Gold Springs in them just because that is what was always in them and naturally it's the best or tied for best with the Springco. There are a couple other things I do to a newly acquired AR but that doesn't pertain to this.

I don't want to derail this but I also don't think its worth me starting a new post about this.

Thank you.

[T2C]

I never paid attention to gas port size or buffer weights on my AR's, but this thread had me wondering. I researched the 16" carbines I have in my stable and learned that all of them are considered overgassed. I do not own pin gauges that small, so I have to rely on the accuracy of internet information on gas port sizes (bonjour). All the carbines are reliable with a wide variety of ammunition from Wolf steel case 62g fmj to hot 40g hunting loads, so I won't be making any changes.

In my limited experience, I don't think gas port size is a serious issue with barrels longer than 14". Increased mechanical noise from the buffer and BCG is secondary to reliability and accuracy IMHO.

[Clint]

It's entirely possible to over gas any barrel, but the longer gas systems have lower port pressures and are more forgiving.

A .005" larger port on a MID-length barrel may be controllable with a heavy buffer, but .005" larger on a Carbine gas barrel may start to cause issues.

I never paid attention to gas port size or buffer weights on my AR's, but this thread had me wondering. I researched the 16" carbines I have in my stable and learned that all of them are considered overgassed. I do not own pin gauges that small, so I have to rely on the accuracy of internet information on gas port sizes (bonjour). All the carbines are reliable with a wide variety of ammunition from Wolf steel case 62g fmj to hot 40g hunting loads, so I won't be making any changes.

In my limited experience, I don't think gas port size is a serious issue with barrels longer than 14". Increased mechanical noise from the buffer and BCG is secondary to reliability and accuracy IMHO.

[lysander]

My research shows the O ring was adopted as an interim fix until the .mil could be convinced to approve the then new Colt extractor spring to the system, something the .mil resisted because it would “add a new NSN for the same part”. Until the upgraded spring was approved, they were stuck using the rifle extractor spring which was not strong enough for full auto in the M4 and prone to early failure.

Using an O ring introduces its own set of problems. O rings wear out, dry out and deteriorate. When the O ring starts deteriorating, the pieces impede extractor function.

Once institutional inertia was overcome and the upgraded Colt spring replaced the old spring, extraction issues in military M4s have been greatly reduced, if not eliminated. Over the years, I’ve only seen one Colt extractor spring prematurely fail and that was in one of my bolts. I suspect I damaged it during install

Bottom line- You can use the upgraded Colt spring which is proven to work. Or you can take your chances with the spring that made a redesigned spring necessary.

The "new" gold spring design was approved in December 2002, and the NSN assigned in February 2003, and incorporated into the bolt drawing in March 2003, which is around the same time as most all of the other improvements, the heavy barrel, the heavy buffer, and many other minor things.

That is a fairly timely change.

I think you'll find the delay was production and fielding. It is one thing to draw a pretty drawing and assign it a number in the catalog, it is another thing to make a millions of them and get them out to the users for replacement. Then there is the possibility that the initial fielding plan was to replace through attrition, and mandatory replacement at depot rework. This means that unless they break in the field, they are not replaced until it goes back to depot for rework.

[T2C]

It's entirely possible to over gas any barrel, but the longer gas systems have lower port pressures and are more forgiving.

A .005" larger port on a MID-length barrel may be controllable with a heavy buffer, but .005" larger on a Carbine gas barrel may start to cause issues.

The shortest barrels I have considerable experience with are 14.5". In your experience how many rounds would it take for a gas port to erode to .005" larger than on a new 16" barrel if shooting at a moderate pace, no magazine dumps, etc.?

[MistWolf]

MistWolf I would like to ask you your opinion on the Colt Gold Extractor Springs compared to the 5 Coil Springco Extractor Springs, which do you think are the best? Or are they about equal?

I prefer to recommend Colt extractor springs because I have first hand experience with them.

I have very little hands on experience with the Sprinco spring. However, I did have a discussion on the subject with Will Larson who had extensive experience working on ARs (along with other families of weapons) in a combat zone as well as here in the US. He thought enough of the Sprinco spring that he recommended Sionics and SOLGW use them in their ARs. Will's bona fides were good enough that I recommend the Sprinco springs based on his say so. I haven't heard any complaints from anyone using the Sprinco spring.

I see no reason to replace a Sprinco spring with a Colt spring or vice versa.

Will passed away not long after I took his armorer's course. He is missed.