[starsnuffer]

It absolutely depends on the ammo, like most AR's.

With M855, it ejects about 1:30 and high, well in front of the carbine. With steel cased 55 grain, it ejects straight to whoever is standing next to you at eye level reliably.

-W

 

[Grumpy]

Mine ejected perfectly to the 3 o'clock as a properly built new AR should running milspec ammunition (which I do. Federal M193).

After re-profiling the barrel, cutting to 14.5 and perm attaching a flash hider is started ejected to about the 4 o'clock to 4:30 position. Typical when the dwell time has been reduced and less gas gets in the system.

This is perfect for me though as I plan on running with a suppressor which will kick the ejection back to the 2 o'clock-ish position as it up-gasses the gun which is typical for suppressors.

All of that being said, I run my MR556 upper with the HK red dot buffer and spring which is significantly heavier then a standard AR buffer and significantly stronger then a standard AR spring. To use any standard AR buffer and spring combo will result in excessive bolt speed and an ejection patten similar to starsnuffers who's gun appears to be either way overgassed or running underpowered buffer/spring combo, or even has a weak or fouled ejector spring, overly strong extractor system (added crane O ring perhaps?) or perhaps a combination of all.

 

[Montrala]

My ejects empties outside of rifle every time it goes bang. This is actually all I care for

 

[Grumpy]

My ejects empties outside of rifle every time it goes bang. This is actually all I care for

My car runs every time I turn it on too.

But that doesn't mean that I don't have it timed, tuned, fluids replaced per the maintinence schedule and pay attention to it's performance when I drive it...... Just sayin'....... ;-)

 

[hkdoc07]

3 to 4 o'clock using pmc bronze. Only mod is an aac miter flash hider.

Good stuff.

 

[Grumpy]

3 to 4 o'clock using pmc bronze. Only mod is an aac miter flash hider.

Good stuff.

Using the supplied HK red dot buffer and spring or full rifle? Type and barrel length?

 

[starsnuffer]

Mine ejected perfectly to the 3 o'clock as a properly built new AR should running milspec ammunition (which I do. Federal M193).

After re-profiling the barrel, cutting to 14.5 and perm attaching a flash hider is started ejected to about the 4 o'clock to 4:30 position. Typical when the dwell time has been reduced and less gas gets in the system.

This is perfect for me though as I plan on running with a suppressor which will kick the ejection back to the 2 o'clock-ish position as it up-gasses the gun which is typical for suppressors.

All of that being said, I run my MR556 upper with the HK red dot buffer and spring which is significantly heavier then a standard AR buffer and significantly stronger then a standard AR spring. To use any standard AR buffer and spring combo will result in excessive bolt speed and an ejection patten similar to starsnuffers who's gun appears to be either way overgassed or running underpowered buffer/spring combo, or even has a weak or fouled ejector spring, overly strong extractor system (added crane O ring perhaps?) or perhaps a combination of all.

Try yours with 62 grain M855 and see where it ejects? The only mod to mine is a battlecomp 2.0 on the end, stock buffer/spring and 16 inch barrel.

-W

 

[Grumpy]

Try yours with 62 grain M855 and see where it ejects? The only mod to mine is a battlecomp 2.0 on the end, stock buffer/spring and 16 inch barrel.

-W

I've always had similar results with M855 and M193 on ejection pattern in the past. Perhaps the 416 piston system is more sensitive to variances, but I doubt that it's that sensitive to give such a wide variation between the two to creat such disparity in the ejection pattern.

I'll try it anyway for ****s and giggles though.

 

[starsnuffer]

I eject straight 3 oclock with 55 grain steel cased crap. I always thought it was the steel case bouncing off the deflector causing it to eject that way, not the bullet itself. I should experiment with normal 55 grain stuff. I guess I never really thought (or cared) too much about it until this thread.

-W

 

[forFREEDOM]

My 416 ejects consistently between 3 and 4 oclock with 55 grain of all brass sorts using a friends Geissele high-speed trigger. Steel casings are usually at 3 to 3.5, but still all in the same general vicinity.

Mobile clip...
http://s295.photobucket.com/albums/mm157/HKforFREEDOM/HKs/?action=view&current=IMG_0538.mp4

 

[Grumpy]

Ejection behavior is a product of bolt speed (assuming all parts are within operational perameters). So a gun with all parts within spec running properly made springs that are well within their operational life and shooting milspec ammunition *should* have a consistent ejection pattern, with the ideal throw being to the 3 o'clock position.

Yes, StarSnuffer, the brass deflecting off of the brass deflector is partially why it ejects where it does, but the speed and angle at which the brass impacts said brass deflector are also part of the equation. The weight of the bullet only really has a say on the velocity of the round for the most part. Bullet weight *may* have a slight impact of bolt speed, but a very minor one. What really matters is the pressure loadings of the ammunition used. NATO spec ammunition burns hotter and has more pressure hence more velociy and more gas in the system and causes more bolt speed. Civilian manufactured ammunition is generally loaded to SAAMI specifications and has lighter pressures and runs the bolt at a slower speed. All of that steel case ammunition is loaded to cooler SAAMI specifications and runs the bolt slower.

Of course spring wear over time can affect the brass throw. A worn action spring (what most people call the buffer spring) will allow the bolt to cycle faster making a gun throw brass further forward. A worn ejector spring will not push the brass from the bolt face quick enough and cause it to eject later and throw the brass forward as if the gun were running a higher bolt speed.

It seems as if HK designed the 416 and MR556 to have a very healthy gas system and compensated for this by adding a very heavy buffer and a much stronger action spring (the red dot buffer/spring system). Running a 416 or MR upper on a standard lower with a carbine or H buffer will allow excessive bolt speed.

How does this affect you? While a gun running "hot" will keep working under a wider variety of conditions and in dirtier environments, it WILL reduce the life of the gun as parts impact harder, cause more internal wear, etc. It also slows follow up shots as the gun recoils harder and takes more effort to control. For those who invested a metric ton of money into their guns, this may be cause for concern. I, for one, don't baby my guns regardless and wrote off my MR556 the moment I bought it. I know it's going to be shot a lot, beaten up, and used heavily. But that doesn't mean that I don't want it to last as long as I can, so I pay attention to the guns behavior. I cut the barrel back to 14.5 knowing that the reduction of dwell time was going to cause the gun to run a little lighter in the gas system, thereby reducing wear on the gun, but not enough to cause any function issues. It also means that I can run suppressed without increasing system pressure to excessive levels. (suppressors increase pressure in the system which increases bolt speed).

Paying attention to ejection with an understanding of what afffects it and why is part of maintaining a healthy running gun and allows you to account for parts wear before the gun has a malfunction or parts breakage and you don't know why.

 

[starsnuffer]

Great info Grumpy, thanks.

So given the MR556 system, it seems the only thing I could do if my gun is running hot is to decrease the gas port size in the piston block?

-W

 

[Grumpy]

Great info Grumpy, thanks.

So given the MR556 system, it seems the only thing I could do if my gun is running hot is to decrease the gas port size in the piston block?

-W

Negative. Frankly, there is no way to reduce your barrels gas port.

Are you running a full MR556 rifle, or an MR556 upper on a regular AR15 lower? If so, are you using the red dot buffer and action spring? Or are you running a 416 upper on an AR lower? Barrel length?

*If* you are running a standard MR556 and using the supplied red dot buffer/spring, Then there's not much for it. Round count will also have something to do with it. How many rounds do you have through the rifle? Perhaps there's some foulding in the ejector channel that is slowing it's operation and mimicking a fast bolt. Or, if your round count is high, perhaps your ejector spring is past its usefull life and simply needs replacing.

Another possibility could be your extractor is over tensioned. Does it have a crane "O" ring? Excessive extractor claw tension can also mimick excessive bolt speed as it can prevent the brass from exiting the ejection port in a timely manner by pinching it too hard into the bolt face.

Best things you can tell me to help figure this out is barrel length, which buffer and spring you are running, and round count of the rifle. That will help narrow things down considerably.

 

[starsnuffer]

Between 4500-5000 rounds through it only. Stock MR556 with the red dot buffer and spring, stock 16 inch barrel. I'll take the bolt down and check the o ring when I get home tonight.

-W

 

[Grumpy]

Between 4500-5000 rounds through it only. Stock MR556 with the red dot buffer and spring, stock 16 inch barrel. I'll take the bolt down and check the o ring when I get home tonight.

-W

Ah. Makes sense.

My first area to look would be the action spring(buffer spring) and ejector spring.

Your round count is high enough that both of those are nearing end of operational life.

Ordering an extra power CAR spring from Wolff spring *might* be the solution. I say *might* because I don't know for sure and am guessing that the extra power spring will be somewhat close to the HK provided spring in power.

Ejector srping getting weak will also add to this or be the cause, but usually this sort of behavior is a mix of the two (buffer spring and ejector spring).

Easy and cheap fix to keep your gun running properly, reducing excess wear, and preventing it from failing at a later date.

Lastly, I would add that the op-rod spring be checked and replaced as well as it is now a fundamental part of the system. While the action(buffer) spring and ejector spring can be had on the open market (wolff for the action spring and any new AR15 ejector spring), the op-rod spring will have to be gotten from HK because there are no aftermarket manufacturers of this spring that I know of.

 

[Montrala]

...Your round count is high enough that both of those are nearing end of operational life.

Ordering an extra power CAR spring from Wolff spring *might* be the solution. I say *might* because I don't know for sure and am guessing that the extra power spring will be somewhat close to the HK provided spring in power.

I do not think this is end of operational life. My MR223 at same "mileage" had no problem with springs. I think that HK416 that shot 25.000 rounds in acceptance tests did not have them replaced as well

As to spring ratios check this link (HK spring included):

Action Spring Analysis - M4Carbine.net Forums

Ejection patterns diagnostics made easy (from M4C as well):

 

[starsnuffer]

Thanks guys, that's great info.

I'll order some new springs and try them out, even if they're not the issue it can't hurt having spares.

I'll let you know when I get them in and sorted out.

-W

 

[Grumpy]

"think" or know? There's one thing I do know and that is the number of times a spring is compressed directly coorelates to spring fatigue. If you'll notice that HK makes their springs from the same material that Colt does (merely at at higher spring strength), and Colt springs are lucky to last 5000 rounds of optimal performance before starting to degrade. The spring in question here IS degrading by this point. Add in a fatigued ejector spring and things show even worse.

I recently saw a guys gun with 10K rounds down the pipe, and while he wasn't having failures yet, the rubber buffer cap on the end of the buffer itself was squashed, cracked, and starting to mushroom. A quick replacement of the action spring and all the springs in the BCG and his gun was back to where it should have been (he also of course replaced the rubber buffer).

Remember what I keep saying about excessive internal wear? Just because the gun "works" doesn't mean it's working *right*.

And let me tell ya, for all the great things I've heard about torture tests and the like, the one thing they never mention is regular spring meintinence because it's considered normal to change springs at various cycles in a machines life. When they say with no "parts" replacement, I can easily see that. Meaning no bolts have broken, the fireing pin, extractor, ejector, etc. etc. etc. are all fine. Saying a gun made 25,000 rounds without replacing a good majority of the srpings would be like me saying I ran my car for 25,000 miles without ever changing or adding oil to my engine. Sure the gun is good, but the springs simply are not that capable.



So, what I said still stands. Look at the action spring and the ejector spring in specific. replace as necessary and if that doesn't change the ejection pattern, then i'd start looking elsewhere.

P.S. you do know that ejection chart is virtually universally despised on M4C.net, right?

 

[Grumpy]

One of the interesting pieces of info that Montrala linked to is that the HK action spring is slightly weaker then the wolff XP spring by approximatly a pound. That means that if you replace your action spring with a wolff spring, it will help the bolt slow down considerably and make things easier on the internals of your rifle.

Don't forget to change the ejector spring as well.

p.s. for what it's worth, i'm seriously considering contacting HK about spare op-rod springs as that is now a major component in the system and takes a good couple or more pounds of compression off of the action spring. The bad part about it is that it is allowed to reach full compression, which no other spring in the system is allowed to do, and that is when the worst wear sets in on a spring. This would lead me to believe that the op-rod spring needs to be changed a heck of a lot more often to keep the gun in "optimal" running performance.