What have I done wrong now?

[copemech]

Ok, so first time out with mine and a cheap 3x9 mounted and using cheap Monarch steel 145 gr to cycle it in, the gun ran good and killed my shoulder.

Couple of weeks later and here I am with a Magpul stock with PAD and a Tacticool brake installed, using same cheap ammo to sight in new scope.

Gun will not run two rounds without jamming. New round stuck at an angle to chamber , but when it does cycle fully there is no round in the chamber.

I am not sure if it is short or quick cycling? It does pick up a new round mostly, but jams at an angle about half stroke.

It spits the steel out at 90-100 deg at about 8-ft or possibly more, which seems a lot to me, but I am not sure what is normal.

And the only thing dynamically changed is the Brake?

It is lubed up, and I ran a cleaner and boresnake through it after the first 40 rds, using PMAGs 10's, and tried a different one just in case. Same as before.

My thoughts are that the restricted exit orface on the brake may increase gas pressures somehow to cause quick cycling, as it will not pick up the new round at times, possibly wrong?

All works fine charging by hand, which is allways!!!! Either to feed or un lodge angled round.

Thoughts appreciated!

 

[Fourth Horseman]

I was going to say magazines, but you've tried more than one. I'm having a hard time believing a brake could cause these malfunctions, but as that's the only thing you've changed I'd recommend taking the brake off and head back to the range with the bare muzzle to see if the problems go away.

The only other thing I can think to try would be a different weight buffer, maybe a heavier one to slow the action down? That's assuming it is cycling too fast. But the brass ejecting at roughly 90 degrees seems to indicate it's not cycling too fast, doesn't it?

 

[tlay]

You said that you changed the stock to a magpul stock. Did you pull the recoil buffer tube off? Maybe you didn't put it back on properly. It has to be screwed in to the proper length and not too far in. If you did not take the tube off then maybe you need a heavier weight buffer. Also it might help to lube it.

 

[MistWolf]

You'd have to cycle that bolt pretty fast to outrun a good mag. First thing you need to do is get good factory 308 ammo between 150 and 168 grs and see how the rifle runs with that. It sounds like the ammo is underpowered and causing short stroking

 

[apiccola]

Take a look at the casings and see if there are any aggressive extraction marks or unusual side abrasions compared to casings when your rifle was cycling properly .. the aggressive marks could be a sign of fast cycling [bolt carrier set in motion too early while the casing is still at full expansion in the chamber]. If this seems to be the case, add buffer weight.

Also, inspect your bolt & gas components to make sure you do not have any gas leaks or impingements ... in another thread, someone experiencing similar symptoms discovered that their rifle had worn gas rings which were allowing gas to blow by. In that circumstance, replacing the worn rings cured the problem.

 

[copemech]

You said that you changed the stock to a magpul stock. Did you pull the recoil buffer tube off? Maybe you didn't put it back on properly. It has to be screwed in to the proper length and not too far in. If you did not take the tube off then maybe you need a heavier weight buffer. Also it might help to lube it.

No changes to the tube, just a slide on.

[/QUOTE]You'd have to cycle that bolt pretty fast to outrun a good mag. First thing you need to do is get good factory 308 ammo between 150 and 168 grs and see how the rifle runs with that. It sounds like the ammo is underpowered and causing short stroking

That is what I thought as well and explains no pick-up at times, but how the others are getting lodged at an angle under the bolt is ? Unless it is simply recoil letting them rise and bolt not catching the rear of the case.

 

[copemech]

Now that I think back, I cannot swear the first 40 rds that ran well were identicle to the last Monarch 145gr. Similar little box, but it is possible they were 150gr Tul or something.

Even with the stock setup and cheap scope and pain flinch, it seemed I was getting better groups first time out at about an inch at 50 yds, better scope, less recoil and I am throwing scattered 1.5 groups without consistency, and I do not think it is me, prolly **** ammo.

 

[copemech]

Take a look at the casings and see if there are any aggressive extraction marks or unusual side abrasions compared to casings when your rifle was cycling properly .. the aggressive marks could be a sign of fast cycling [bolt carrier set in motion too early while the casing is still at full expansion in the chamber]. If this seems to be the case, add buffer weight.

Also, inspect your bolt & gas components to make sure you do not have any gas leaks or impingements ... in another thread, someone experiencing similar symptoms discovered that their rifle had worn gas rings which were allowing gas to blow by. In that circumstance, replacing the worn rings cured the problem.

None of those signs that I seen, only dings on the cases were from lodging at angle on the ramps. And it is new and has been disassembled , inspected and lubed. I run grease on the carrier, and oil on the bolt to stay wet.

 

[MistWolf]

No changes to the tube, just a slide on.

You'd have to cycle that bolt pretty fast to outrun a good mag. First thing you need to do is get good factory 308 ammo between 150 and 168 grs and see how the rifle runs with that. It sounds like the ammo is underpowered and causing short stroking

That is what I thought as well and explains no pick-up at times, but how the others are getting lodged at an angle under the bolt is ? Unless it is simply recoil letting them rise and bolt not catching the rear of the case.

From your description, you're experiencing what is called a "Bolt Over Base" or simply a "bolt over". This happens either when the magazine sits too low, or from short stroking. Since you're using cheap ammo, your problem is most likely short stroking resulting in a bolt over. When the carrier short strokes, the bolt does not come back far enough to catch the rim of the case. However, the body of the case sits high enough to get caught by the bolt and push it partially out of the mag, jamming everything up.

Your problem is from undergassing from underpowered ammo or there is a gas leak and/or a blockage in the gas system. Switch to quality made standard velocity 308 ammo with a bullet weight of 150-168 grains and see if the problem persists. Troubleshoot one thing at a time and start with the simplest solution

 

[Swannie]

@CopeMech, I had a very similar problem with my MP 10 when I first bought it. It caused me all kinds of headaches and I finally sent it back to the factory for repairs. All they would tell me is that they replaced the mag and repaired the barrel.
When I had the problem of not ejecting, the rounds would get jammed half way between the chamber and the mag. The rounds would also get long scratches on the brass and dents in the shoulders from the bolt carrier group.
My suspicion is that it's the steel mags that I was using too along with needing the feed ramp smoothed. However, I'm not a gunsmith and I'm new to ARs. I bought a S&W MP 15/22 and any time I use the factory mag with it, the gun jams because of the mag. If I use after market mags, the gun works fine. I have only used factory ammo from Federal in the MP 10 and I was using Remmington factory ammo for the MP 15/22.
The link to a previous thread that I talked about on is:http://smith-wessonforum.com/smith-...17-new-m-p10-cycling-issue.html#post137331257

 

[rojodiablo]

No changes to the tube, just a slide on.

QUOTE: 'You'd have to cycle that bolt pretty fast to outrun a good mag. First thing you need to do is get good factory 308 ammo between 150 and 168 grs and see how the rifle runs with that. It sounds like the ammo is underpowered and causing short stroking'

That is what I thought as well and explains no pick-up at times, but how the others are getting lodged at an angle under the bolt is ? Unless it is simply recoil letting them rise and bolt not catching the rear of the case.

Let's not forget for one second that many, MANY brand new M&P 10's have had a slew of feed issues. They are a particularly picky rifle in many cases.
After working over a good 15 of these for guys now, my recommendation is that if the rifle worked fine with the stock muzzle flash hider, reinstall it and try the rifle.

If it works fine, then try it with a minimum of 3 manufacturers' ammo. If it will run them all without issue, then the rifle is well set up with that combination.
At that point, if you wish to run the muzzle break, you will likely need to look to altering the buffer weight to absorb more of the increased back pressure. OR, install an adjustable gas block so you can get the rifle to deliver acceptable gas amounts.

If the rifle does not like multiple types of ammo, then you are best off to plan on tuning the rifle until it does accept different ammo types. You can do this in conjunction with the brake, work on buffer weight or an adjustable gas block.

Your AMMO is not the culprit here: You have stated that the rifle is ejecting some-odd 8feet away. There is PLENTY of force to stroke the bolt back fully with that much ejection force. Your bolt is moving too fast with the current setup, plain and simple.

 

[rojodiablo]

I was going to say magazines, but you've tried more than one. I'm having a hard time believing a brake could cause these malfunctions, but as that's the only thing you've changed I'd recommend taking the brake off and head back to the range with the bare muzzle to see if the problems go away.

The only other thing I can think to try would be a different weight buffer, maybe a heavier one to slow the action down? That's assuming it is cycling too fast. But the brass ejecting at roughly 90 degrees seems to indicate it's not cycling too fast, doesn't it?

90-100 degrees is ideal, and an ejection of 8ft. or more indicates a LOT of pressure being delivered to the bolt for cycling the next round.
You are correct on both fronts.

Now; FWIW, my rifle will run a magazine with 4-5 different types of ammo in it all mixed up, and it does not flinch when it comes to cycling that ammo. When set up properly, this ammo speculation becomes a pure myth. In most cases where a rifle has issues not cycling the bolt fully, the rifle is under-gassed via a small gas port opening, or a restriction via the gas block not being placed properly over the gas port.
Also; if the magazines were functioning perfectly well on day 1, there is pretty much ZERO chance they are now suddenly not seating properly into the rifle. A magazine issue tends to manifest itself immediately if the seating height is the problem. Most magazine issues come from wear and tear, and it is usually a grimy/ worn follower that is the problem, regardless of whether it's a rifle or pistol.

 

[copemech]

90-100 degrees is ideal, and an ejection of 8ft. or more indicates a LOT of pressure being delivered to the bolt for cycling the next round.
You are correct on both fronts.

Now; FWIW, my rifle will run a magazine with 4-5 different types of ammo in it all mixed up, and it does not flinch when it comes to cycling that ammo. When set up properly, this ammo speculation becomes a pure myth. In most cases where a rifle has issues not cycling the bolt fully, the rifle is under-gassed via a small gas port opening, or a restriction via the gas block not being placed properly over the gas port.
Also; if the magazines were functioning perfectly well on day 1, there is pretty much ZERO chance they are now suddenly not seating properly into the rifle. A magazine issue tends to manifest itself immediately if the seating height is the problem. Most magazine issues come from wear and tear, and it is usually a grimy/ worn follower that is the problem, regardless of whether it's a rifle or pistol.

I appreciate your and all elses comments and suggestions. As you have read into this the potential for my confusion, as I seemed to get good ejection, however through the course of this, several items got brought up here and by a friend who is an AR nut.

Obviously cheap ammo, but these were indeed 145gr, and with a potentially pickey gun to begin with, well?

Then the potential of the bolt literally dragging the case halfway in on a short stroke, as the edges are sharp enough to catch and drag, and the bolt was not but halfway up the case on a jamb.

Another point made was if the bolt locked back on last round, answer, not that I recall, yet possibly half the time with the first batch, yet I did not think too much of it at the time.

Although I totally dislike overly pickey guns, I do totally understand the necessity for an auto action to run within some standards of pressures and such. As stated, I shall try to establish a new baseline here, as Wally World had some ammo today at a somewhat reasonable cost of $18 per box from some ferign company called Reminton or something like that, came in a green box that said a bunch of stuff, but basically 150gr soft points. I figure that would be about as close to a standard charge as you would find without going to heavier weight. Gas pressures should be ok as a baseline. And if nothing else I can keep the brass!

At the price of $30-40 a box, some of that stuff is just nuts!

I did not expect perfection, just want to run -in the gun, so I am still ok, we shall see how it does next time out.

ps- the old rcbs press may have to come out of the closet, as I do have methods to make the machine cycle if need be!

 

[rojodiablo]

I appreciate your and all elses comments and suggestions. As you have read into this the potential for my confusion, as I seemed to get good ejection, however through the course of this, several items got brought up here and by a friend who is an AR nut.

Obviously cheap ammo, but these were indeed 145gr, and with a potentially pickey gun to begin with, well?

Then the potential of the bolt literally dragging the case halfway in on a short stroke, as the edges are sharp enough to catch and drag, and the bolt was not but halfway up the case on a jamb.
Another point made was if the bolt locked back on last round, answer, not that I recall, yet possibly half the time with the first batch, yet I did not think too much of it at the time.

Although I totally dislike overly pickey guns, I do totally understand the necessity for an auto action to run within some standards of pressures and such. As stated, I shall try to establish a new baseline here, as Wally World had some ammo today at a somewhat reasonable cost of $18 per box from some ferign company called Reminton or something like that, came in a green box that said a bunch of stuff, but basically 150gr soft points. I figure that would be about as close to a standard charge as you would find without going to heavier weight. Gas pressures should be ok as a baseline. And if nothing else I can keep the brass!

At the price of $30-40 a box, some of that stuff is just nuts!

I did not expect perfection, just want to run -in the gun, so I am still ok, we shall see how it does next time out.

ps- the old rcbs press may have to come out of the closet, as I do have methods to make the machine cycle if need be!

To the sections in bold: The bolt drags when going FORWARD at ultra high speed, and it leaves no mark on the back 1/4 of the round in general because the bolt rebounds so quickly that it starts to pass the bullet rim before the magazine spring has pushed the round into position.
IF a rifle FTE (Fails to Eject) it is oft due to low powered ammunition. And, the drag mark is VERY DIFFERENT: The drag mark goes from front to back, not back to front. The spent brass is usually on the ground right next to you, or hung up inside, cockeyed and oft stuck in the ejection port sideways.
(Look for a metal curl or a stop edge on the scratch in the brass. It's usually there to tell you which way the bolt is actually dragging. You will likely need a magnifying glass)
A bolt which hits the new bullet going really fast where the bullet has not fully risen into position will drive the round cockeyed because the bullet is still feeding UP as it is snagged from behind by the bolt and driven at a slightly off angle feed. With the 223/ 556, the round is smaller, and it seems to affect that caliber much less overall. (The feed ramps are larger by percentage, and angle of feed seems to be a bit better at really high feed speeds.) With 308, and especially with soft tipped ammo, it is more of a potential issue.

I hope I have explained a bit better for you the how and why of the rifles' feed issues. Definitely NOT an issue only visited by S&W's 308 platform.

As to pressure standards, this weekend I shot Wolf/ WPA. German 7.62 surplus....circa 1953, US surplus 7.62, circa 1958, Federal soft points, some reloads from the gun show, and some CBC M80 ball, specifically because there were several guys HERE who were upset with the ammo in their rifle. 250ish rounds later, and not one issue. The closest to a **** was the gun show reloads. One would have the powder of a 308. The next had the powder of maybe a blackpowder rifle, or a 223..... and then the next round would have a 30-06 powder charge in it (seemed like it) Even with that junk, the rifle chugged along without complaints.

What I am saying is; the rifles are already mildly over-gassed to cope with lower power ammo. The muzzle break probably enhanced that situation.

 

[rojodiablo]

@CopeMech, I had a very similar problem with my MP 10 when I first bought it. It caused me all kinds of headaches and I finally sent it back to the factory for repairs. All they would tell me is that they replaced the mag and repaired the barrel.
When I had the problem of not ejecting, the rounds would get jammed half way between the chamber and the mag. The rounds would also get long scratches on the brass and dents in the shoulders from the bolt carrier group. My suspicion is that it's the steel mags that I was using too along with needing the feed ramp smoothed.

The FTE is a result of too little backpressure. One of four things: Weak ammo. The gas port is too small or blocked. The rifle is so filthy that the gas tube is clogged. The gas tube is kinked or pinched.
My guess is #2. Gas port was drilled a little on the small side, or the gas port was blocked by a slightly off set gas block. Fixed rather quickly when the rifle was inspected and torn down.

Your post helps to highlight the differences in issues with the gas cycle problems

 

[MistWolf]

I forgot to mention that the mags supplied by S&W are not worth keeping. I retired the 10 rounder that came with mine as soon as I could get PMag replacements. Most experienced shooters do. The factory 10 rounder was rough, hard to load and has sticky feed.

There is underpowered 308 ammo out there. I got a lot of CAVIM that would not cycle the action. Had to manually cycle the rifle after each shot even from the PMags. Switch to commercial ammo fixed that.

The last thing I'd reccommend with the M&P-10 is opening up the gas port. Once you do, there's no going back. The recoil of mine is sharp enough to tell me that opening the gas port would likely be a mistake. First, I'm going to see how it shoots with the BABC, then experiment with the buffer weight & action spring. Not because I'm having trouble with short stroking but because recoil is a bit sharp.

It's popular to blame bolt overs on high carrier speeds and attempt to fix the problem with heavier buffers & springs. But, in tracking posts about bolt overs, every one has been fixed by solving short stroking, not slowing down the carrier. The exception has been when the problem was traced to a bad magazine

 

[rojodiablo]

I forgot to mention that the mags supplied by S&W are not worth keeping. I retired the 10 rounder that came with mine as soon as I could get PMag replacements. Most experienced shooters do. The factory 10 rounder was rough, hard to load and has sticky feed.

There is underpowered 308 ammo out there. I got a lot of CAVIM that would not cycle the action. Had to manually cycle the rifle after each shot even from the PMags. Switch to commercial ammo fixed that.

The last thing I'd reccommend with the M&P-10 is opening up the gas port. Once you do, there's no going back. The recoil of mine is sharp enough to tell me that opening the gas port would likely be a mistake. First, I'm going to see how it shoots with the BABC, then experiment with the buffer weight & action spring. Not because I'm having trouble with short stroking but because recoil is a bit sharp.

It's popular to blame bolt overs on high carrier speeds and attempt to fix the problem with heavier buffers & springs. But, in tracking posts about bolt overs, every one has been fixed by solving short stroking, not slowing down the carrier. The exception has been when the problem was traced to a bad magazine

Since the M&P10 has come out, I have now fixed feed issues on 13 of them. A few went back to the factory. All the ones we tuned will take about any ammo and work with any magazine that fits the DPMS profile magazine/ LR308 magazines.

90% of the rifles have the same issue. The bolt simply moves very fast, and the bolt is ABSOLUTELY recoiling completely and ejecting ammo rather well. (Average ejection is 6-8ft! and at the shooters' 4-5o'clock) The issue is to slow down the recoil, and more importantly, to increase dwell time. Regardless of the bolt weight combination, if there is not sufficient dwell time for the round to rise? The bolt will ride over the round consistently.

If you decide to use the search feature here in this sub forum..... you will see that for over a year now, I have been helping people get these rifles sorted out.
And you'll find that after we posted our findings HERE.....S&W came out with some materials to correct these feed issues with their rifles. (Yes- they read the forum. ) You can guess at what they have found and how they have been modifying the rifles to get them to feed better......

If you feel that the felt recoil of the rifle tells you there is plenty enough pressure that there is no need to open the gas port, then it would be IMPOSSIBLE to say the rifle is short stroking.
My suggestion is directly aimed at the possibility of having a rifle that has 3 likely possible issues-1. Gas block not seated correctly and blocking port partially. 2. Filthy rifle. And lastly, 3. Gas port was drilled too small. If you are wondering how this can happen? Drill bits break in a machine shop..... and it does happen. 1 of the 13 rifles I have torn down and had to rework had this issue. Sized the port up and it was remedied. It IS the last resort, I agree with you on that.

I'll stand on the dozen or so posts already made on this subject in here, and the consistent fixes to the rifle that are pretty much universally the same.

 

[copemech]

I forgot to mention that the mags supplied by S&W are not worth keeping. I retired the 10 rounder that came with mine as soon as I could get PMag replacements. Most experienced shooters do. The factory 10 rounder was rough, hard to load and has sticky feed.

There is underpowered 308 ammo out there. I got a lot of CAVIM that would not cycle the action. Had to manually cycle the rifle after each shot even from the PMags. Switch to commercial ammo fixed that.

The last thing I'd reccommend with the M&P-10 is opening up the gas port. Once you do, there's no going back. The recoil of mine is sharp enough to tell me that opening the gas port would likely be a mistake. First, I'm going to see how it shoots with the BABC, then experiment with the buffer weight & action spring. Not because I'm having trouble with short stroking but because recoil is a bit sharp.

It's popular to blame bolt overs on high carrier speeds and attempt to fix the problem with heavier buffers & springs. But, in tracking posts about bolt overs, every one has been fixed by solving short stroking, not slowing down the carrier. The exception has been when the problem was traced to a bad magazine

Yes, I think that is kinda where I am at with this so far, as the mags were p-mag 10's for the sake of shortness at the range I think they should be fine.

 

[copemech]

Since the M&P10 has come out, I have now fixed feed issues on 13 of them. A few went back to the factory. All the ones we tuned will take about any ammo and work with any magazine that fits the DPMS profile magazine/ LR308 magazines.

90% of the rifles have the same issue. The bolt simply moves very fast, and the bolt is ABSOLUTELY recoiling completely and ejecting ammo rather well. (Average ejection is 6-8ft! and at the shooters' 4-5o'clock) The issue is to slow down the recoil, and more importantly, to increase dwell time. Regardless of the bolt weight combination, if there is not sufficient dwell time for the round to rise? The bolt will ride over the round consistently.

If you decide to use the search feature here in this sub forum..... you will see that for over a year now, I have been helping people get these rifles sorted out.
And you'll find that after we posted our findings HERE.....S&W came out with some materials to correct these feed issues with their rifles. (Yes- they read the forum. ) You can guess at what they have found and how they have been modifying the rifles to get them to feed better......

If you feel that the felt recoil of the rifle tells you there is plenty enough pressure that there is no need to open the gas port, then it would be IMPOSSIBLE to say the rifle is short stroking.
My suggestion is directly aimed at the possibility of having a rifle that has 3 likely possible issues-1. Gas block not seated correctly and blocking port partially. 2. Filthy rifle. And lastly, 3. Gas port was drilled too small. If you are wondering how this can happen? Drill bits break in a machine shop..... and it does happen. 1 of the 13 rifles I have torn down and had to rework had this issue. Sized the port up and it was remedied. It IS the last resort, I agree with you on that.

I'll stand on the dozen or so posts already made on this subject in here, and the consistent fixes to the rifle that are pretty much universally the same.

And your exact comments are what still concerns me, and as this one was bought new in December, I would think it may have production mods performed as a later build.

As I am not sure of things, all I can tell is on the second outing it was much more tolerable to shoot(no bruises) with the butt pad and the brake installed, yet it would still hop off target sitting on the bi-pod, so must re-acquire sight picture. Still slinging out the steel case for quite a distance!

I am not sure if fast action can/ will also over ride the stop on last round, yet same principles apply.

Gas block seating? I am not exactly sure how to test it. I had read something about using compressed air to flow ck, yet I have no ref on this.

Not dirty, it is new! I looked at it after first 40 with a buddy that knows about this stuff, bolt was clean, add comments about cheap being dirty, wiped things, sprayed cleaner in the bore and chamber, let sit a sec, then pushed some CLP in the bore and ran snake through twice, reassembled. Bolt still well greased and oiled.

I guess I could allways knock off the gas block just to look at things if I had measures, but I would need educated on proper alignment upon reassembly.

Will set baseline with the Rem ammo, should not take 40 to find out!

I would find other suggestions of buffer/ springs of interest if need be.

 

[rojodiablo]

And your exact comments are what still concerns me, and as this one was bought new in December, I would think it may have production mods performed as a later build.

As I am not sure of things, all I can tell is on the second outing it was much more tolerable to shoot(no bruises) with the butt pad and the brake installed, yet it would still hop off target sitting on the bi-pod, so must re-acquire sight picture. Still slinging out the steel case for quite a distance!

I am not sure if fast action can/ will also over ride the stop on last round, yet same principles apply.

Gas block seating? I am not exactly sure how to test it. I had read something about using compressed air to flow ck, yet I have no ref on this.

Not dirty, it is new! I looked at it after first 40 with a buddy that knows about this stuff, bolt was clean, add comments about cheap being dirty, wiped things, sprayed cleaner in the bore and chamber, let sit a sec, then pushed some CLP in the bore and ran snake through twice, reassembled. Bolt still well greased and oiled.

I guess I could allways knock off the gas block just to look at things if I had measures, but I would need educated on proper alignment upon reassembly.

Will set baseline with the Rem ammo, should not take 40 to find out!

I would find other suggestions of buffer/ springs of interest if need be.

Okay, I can give hints and helps!
1. The rifle will ALWAYS jump off the sight picture, unless you weigh it down a metric ton or so. The AR recoils in BOTH directions, every shot. A kick back, followed by a slam forward. Much more noticeable on the 308 than the 223, especially with a carbine style rifle weighing in under 9lb.
We have a 24" barreled rifle (Tims', not mine) and it weighs in at a svelte 14.5lb. Barrel is 1" diameter, fore grip is extra heavy, the A2 stock has weight in it, and the bipod is very heavy for what it is. This one hardly moves when you shoot it. The gas block is adjustable, and the recoil spring was chosen for the softest one that would function the rifle. His wife likes to shoot it because it does not get 'upset' as she put it.

When the rifle is operating- it moves about 4 times as fast as you can humanly pull the trigger a second time. If the 308AR were a full auto rifle, it would easily cycle in the 400-500 rounds/ minute range without breaking a sweat. No human outruns the bullet, on either side of the bullet!!

Yes indeed, when the bolt is moving that fast, it can easily blow right past the magazine follower and not stop on the last round hold open. That is in fact a good indicator that the bolt is moving very fast, and more importantly, there is not enough DWELL TIME. Dwell time is where the bolt is basically stopped for a nanosecond at the peak of the recoil before it starts pushing forward.
Your gas block is set correctly..... the rifle was functioning well. That tells you the story. An easy way to see if the block is offset is to take an air nozzle and a cotton ball.
Open the rifle up.
Lightly oil the cotton ball and stuff it into the chamber.
Air nozzle goes onto the gas tube. Lightly blow air into the tube, no need to blast it. 5-10psi is plenty. Feel the air at the front of the barrel. If you have very, very little air? The gas block might be offset, or the gas port might have a blockage. If so...... crank the air up to 60 and see what you get. You will not hurt the rifle.
An easy way to tell if the gas block is leaking and letting out excessive pressure (venting) is to spray soapy water on the gas block while doing the air nozzle job with relatively low pressure. Should not see much in the way of bubbles, at 60psi. If the leakage is really bad, you will see powder dust all over the gas block and the port where the gas tube enters the gas block.
It should be noted that a little gas venting is not bad. The rifle will expand and seal things as the barrel gets heated up and the gas tube will seal with the pressures created from firing. 60psi is nothing compared to the pressure developed by the powder being burned in the chamber.

Rifle is clean, I believe you. Saying 'Filthy rifle' is only a reference point. People seem to like to shoot 10K rounds thru their rifle without cleaning..... just to prove it can get dirty. Some relish in dusting them out, or dropping them in mud, etc.

If the rifle performs well with the brake removed still, then the easy and cheap modification is to start by adding weight into the buffer tube and try the rifle with the brake installed. The buffer has weights inside it. Add some more weight, and keep track of what you have added, so you can always go right back to stock as a reference point.