So I finished up my DDLES build, details below mostly to help with diagnosing the problem.




Lower:

DDLES Small Frame VLTOR Lower w/Sig SB15 brace (until tax stamp returns)
Seekins Precision Enhanced Bolt Catch
Heavybuffers.com 9Q-T Buffer with Wolff XP Buffer Spring

Upper:
VLTOR MUR-1S upper
TROS 5" 3-lug barrel
Spikes BAR 7" rail
BCM Gunfighter charging handle (Mod4)
CMMG ramped 9mm bolt (cut for Glock magazines by ADCO)

The suppressor is a Ti-Rant 9 with JB Tactical's 3-lug adapter.

The rest of the parts aren't pertinent to the problems I'm having (sling, optics, etc.)

Problems I'm having:

1. Failure to lock back on an empty mag. The build passes the 'dry fire' test of always locking back on an empty. I swapped out the XP buffer spring for a regular carbine spring which I THINK has cured the problem, but any other suggestions are welcome

2. Stovepipes every 3-5 rounds. Interestingly, it mostly seems to be happening in the first 10 rounds of a 33rd magazine and less so in the next 20 rounds. It happens rarely in a 15rd G19 magazine, but does still occur. I was under the impression a stovepipe was usually a weak extractor spring though?

3. Failure to load on the first round. This happens occasionally - more with the 33rd mags. They have a little bit of play in the magwell, and every now and then when you send the bolt home on a loaded mag, it won't go completely into battery. A slight tug on the bolt relieves pressure on the half-chambered round and when you release the bolt again it will chamber properly, but I'd like to fix this. I am thinking it merely has to do with the wiggle that the magazine has, which alters the angle in which it 'strikes' the feed ramp.

4. This is more of a suppressor issue I think, but I am still curious as to what anybody thinks is the cause. I cannot get a good 25yd zero with the suppressor on. There is so much shift as I work through a magazine that you end up just chasing your impact within about a 6-8" circle. I've checked for baffle strikes, I've tried the suppressor at all three positions on the tri-lug barrel. Nobody can figure out why it's shifting so much. Sometimes it will walk rounds laterally up to 8", sometimes the rounds move in more of a clock-like pattern. I don't have the issue when unsuppressed, and I am positive that it is not a marksmanship problem. It will group 3-4 rounds almost touching, and then the next round will be 5" away. Using 147gr 9mm, of 4-5 different manufacturers, both reman and brand new. American Eagle, Winchester, etc. Any ideas?


I want to be able to trust this thing enough to load up a few mags of 147gr Gold Dots, but I have yet to make it through a 33rd magazine without a stovepipe or failure to feed. Any help is appreciated.

-Twister


ETA: All magazines used are factory Glock magazines.

Get rid of the XP spring

Thanks, I did that already, but that didn't have any effect on problems 2, 3, or 4.

Will do. With or without the XP buffer spring?

Also, could you educate me on how factory-new 147gr would be causing these malfunctions? It still sounds ok with 115gr, but the whole point of this build for me was for use with 147gr...

Mag release spring might be a little weak.  I'd change that for a stronger one.  Mark the base of a few cases with a sharpie, run them through the gun and try to see where the ejector is hitting.  It might need to be tweaked a bit.  Radius the edges of the extractor.  You might need stronger mag springs.

My DDLES Glock 9mm lower has spent over 4 months at my Gunsmith attempting to solve the last round bolt hold open issue. Each time my skilled gunsmith thinks he's figured it out it doesn't work. I have now come to the realization that this lower will never properly lock the bolt back on the last round, and therefore I just have to consider it a 'fun gun' only.

Did you install the reduced spring under the bolt catch? I know it is the obvious question but had to ask....

Yep, reduced spring under the bolt catch. I'm frankly less concerned with the bolt hold open feature, and far more concerned with the stovepipes.

Anybody willing to take a shot at the POI shift with my suppressor?

with a production barrel I'm not surprised with the POI impact shift......it only takes a couple of thousandths of offset between the barrel centerline and the threads to cause the issue.set the barrel up between centers and the measure the OD and see ho much runout you have.......I just spent $4K on a new chuck for a CNC lathe because even with softjaws it wasn't maintaining concentricity while making barrels. The new one is holding dead on with a fresh set of softjaws....

My take is that stovepiping is related to buffer, ammunition or ejector.  Here is an archived thread that shows how the ejector/bolt face relationship can contribute to the problem.
Good Luck.
https://www.ar15.com/archive/topic.html?b=3&f=15&t=545959

I've never had any problems with any of my lowers.

+1 this

Same issues for me.  The BHO has been a real pain in the ass.  I have 3 different buffers and 2 different springs.  It's annoying.   I could never run a carbine course with this build - it would be one problem after another.  So I dropped it off for Cerakote.  It might not run right - but it will be pretty.    

I bought another suppressor - an AAC Ti-Rant 9mm - to dedicate to this build.  I can't get it to run right without a can.  Adding a suppressor just complicates things.  So I'm leaving it off.

All of my experiance is comming from the large frame glock lower as I chose to do the colt pattern for the 9mm, but my experience may be of some help. I have the same issues with the stove popping and the bolt hold open that turned out to be related. The bolt hold open actuator hole that connects the magazine follower to the bho wasn't machined correctly. The hole for the actuator tab was too high causing the bho to bind on the bolt during travel and jamming up the upper and lower receivers. I am using a Rock River bolt so that my Geissele SD3G would work so I had read that the bottom of the nonramped bolt would bind the workings so I used the dreaded Dremmel to remove material of of the top of the bho which solved 80% of the issues but after more examining I noticed how far off the hole in the actuator was off and was still rubbing. I then ordered a RRA 9mm bolt hold open (due to the fact that it had more material to work for the tab that engages the actuator hole) and modified the part to slide into the actuator as flush as possible which resulted in a current 100% reliablility. Although I do not yet have thousands of rounds in this rifle, I feel confident I have fixed my similar issues. I believe the bho was dragging on the bottom of the bolt causing failures to go into battery and failures to eject. I had also polished the bottom of the bolt and chamber which made the cartridges going into battery easier.

I haven't had a chance to get it to the range since I posted this thread, but I did find something (possibly) interesting by hand cycling 15 training cartridges. If I don't rack the bolt with a fair amount of force, the casing stays inside of the receiver when the extractor releases it. Does this mean I have an ejector problem? I am not sure how to fix it.

Does this pertain to the 3-Lug barre that the OP has?  I wouldn't exactly call TROS a "production barrel" since he only makes dozens or at most a few hundred a year.

Like the OP, I'm getting a significant POI shift with my suppressor too.  I've got a green mountain barrel cut down to around 6".   With the can off, it shoots nice tight groups.  When I thread on the can - those groups start opening up.   It's not horrible - but obviously it gets worse as range increases.  I thought the green mountain barrels were supposed to be pretty good.

I'm not totally sweating it right now.  I'll probably but another barrel in this gun anyway.  Supposedly AAC is going to be releasing a tri-lug mount for the Ti-Rant soon.  (so says M. Mers on SilencerTalk)  I have a 1/2 x 28 tri-lug barrel adapter waiting for the appropriate AAC mount.  When that all becomes available I'm probably going to have change my barrel length to minimize the gap between the shoulder of the suppressor and the handrail.

You say you experimented shooting with the suppressor in all 3 different configurations (3 lug).  Did you also try adjusting the suppressor as well?

With the JB Tactical adapter, there isn't a spring loaded piston where you can pull out on the can and rotate it one click in order to shift POI clockwise or counter-clockwise. Is this what you mean by adjusting the suppressor? The problem isn't merely POI shift; I'm only planning on shooting it with the suppressor, so if it was a repeatable POI shift I'd just zero to that. The problem is the POI shift changes constantly, without removal of the can. Within a 15rd magazine, it will jump laterally 6-8", then back to center, then low, high, and left. I will take a picture of my next target.

In the meantime, I read that the ejector should be riding as close to the firing pin hole (high in the bolt's cutout, and as close to center as possible) for reliable ejection. I noticed in mine that it was anywhere from 1/16 to 1/8th of an inch away from the bolt in either direction, depending on how I was holding it since ejector can 'slosh' back and forth in the bolt's ejector channel. Hopefully that makes sense...

Anyway, I bent my ejector up and to the right to bring it almost touching the bolt on the right and top of the ejector. I will report if this helps. It certainly brought the ejector closer to center, but if the stovepipes aren't an ejector problem, it won't matter.

Yes, that is what I meant.  I forgot you are using a fixed barrel spacer/adaptor in that configuration.
Damn, good luck chasing down that gremlin.  Im curious to what you figure out.

As far as the occasional feed issue, I found while playing with the training cartridges and a 33rd mag that it would lock the bolt with a full/partially full magazine if I were resting the gun on the magazine. Even without any pressure from me, the weight of the gun itself was enough to cause the bolt catch to be forced high enough to stop the bolt. I've been tweaking the tab on the bolt catch actuator and I seem to have fixed that. Perhaps this will mitigate the occasional feeding issues. I still have no idea what's going on with the suppressor shift though. And worse, nobody else seems to know either.

Have you tried different mags?

Yes. Three factory Glock 33rd mags, and two factory Glock 15 round (G19) mags. The stovepipe problem does seem to happen less in the G19 mags, for what it's worth. I ordered a pack of three Wolf +5% power springs for the 33rd mags, not sure if that will help or not though.

-Twister

I run my colt pattern with a standard spring and an H3 buffer. Ive had guns that had too much finish on the inside of the receiver where the bolt/bcg runs that caused some problems. That was fixed by removing some of the material with a round wire brush I welded to the end of a screw driver. Is your gas port plugged on your upper receiver? That could cause it to short cycle. Any notable wear on the mage from where the bolt is riding them? Is your bolt ramped? If your bolt isn't ramped and you're not using a 9mm fire control group that could also account for the problems.

Heres a pic of my build.

Are you using some sort of buffer extension, quarters in the buffer tube, etc. to prevent over-travel of the bolt with that H3? My "gas port" is not plugged (I am guessing you're talking about the hole in the upper receiver where the gas tube is normally run through?). Are you saying it will short cycle if the gas port is plugged, or if it isn't? The mags don't seem to have any noticeable wear, and the build has about 500 rounds through it. The bolt was ramped by ADCO as stated in the original post. I am using a rounded hammer and have not had any trigger reset issues. Good looking build. What suppressor is that, and have you noticed the erratic POI shift I have described?

With the H3 buffer I haven't had any issue with over travel. I also am only shooting 147s through her so could be because of the smaller charge in part too. That is the hole I'm referring to. What might be happening is you are losing pressure out of that port before your bolt is able to fully cycle. On a DI gun that is used to assist in the cycling of the BCG, so in this application, since it is not being utilized for that purpose, it is likely acting as a pressure release point. That would definitely be my starting point. This is one of the reasons why I went with parts that are all dedicated for the specific caliber. The can is an Octane 9 HD. I have not had any weird POI shift. Ive only put about 1k rounds down range but everything seems to be working great.

By the time pressure can be released through the gas tube hole, inertia, not pressure, is what is acting on the bolt.

Generally I would agree but, something is causing his bolt not to cycle properly. It sounds like he has tried multiple buffer combos, the mag does not seem to be interfering, multiple ammo types, I am assuming he has oiled his gun... the options are somewhat limited. What's it going to hurt to trying out a 5 cent plug?

Actually, it could be an issue with the feed ramp. Ive had guns portray some of these issues because the feed ramps were too steep, too tall, or too short...

I can't get the feed issues to occur when hand cycling, which is the weird part...

Does anybody know of any downsides to filling the charging handle hole with black RTV silicon? Shouldn't make a difference if I fill that hole or the one in the receiver, and I figure it will be easier to apply it to the charging handle, a removable part, than to get into the gas tube hole in the upper.

Might as well fill in the ejection port as well.  That hole is not your problem.

^^Reeeally? C'mon dude, Its actually not nearly that far fetched. The moment that bolt starts moving back, gas starts escaping with it. The sooner that pressure dissipates, the less force is applied to the bolt. Even if only slight.

The more I think about your combined issues though, the more I think its probably related to your feed ramp. Can you snap a photo toward chamber through the ejection port with a mag inserted?

Also, does your barrel have an indexing key on the extension or is it smooth all the way around?

I also recall some sort of tutorial video about tweaking your extractor on the ddles website. Sorry if I'm all over the board here, just trying to help you spitball here.

It is that far fetched.  The ejection port is closer to the chamber and larger.  Gas takes the path of least resistance.  Also the bullet is out of the bore by then, leaving another larger hole for gas to escape from.

And there's the fact that he mentioned that the short stroking was likely cured by replacing the XP spring with a standard one.  

The stovepipes are likely being caused by a misaligned ejector or an issue with the extractor. The failures to feed could be either the magwell or the feed ramps.

Requested photos at the bottom of this post.

I am going to do my best to refocus this thread. I've gotten a lot of great input and have applied some, and determined others to be less relevant.

Here's where I'm at:

1. As of now, I believe I have cured the last round bolt hold-open LRBHO problems by using a regular spring instead of the XP one. For now, let's consider this issue resolved.

2. Stovepipes: There seem to be a lot of different possibilities for this. I'm not sure how to tweak an extractor (it's kind of like it's own leaf spring in the CMMG bolt; no coil spring for extractor tension), so if somebody knows how to increase tension on the extractor, please share. Just pushing on it with a punch though, it seems quite stiff. What I have been able to tweak is the ejector, which I noticed was riding anywhere from 1/16th to 1/8th from the edge of the bolt cutout. From reading other threads regarding ejector issues, I learned that you really want the ejector to just about kiss the horizontal and vertical 'wall' of the bolt face's ejector cutout (sorry for using less-than-technical verbage). I was able to bend the extractor up and to the right, and it now rides much closer to the center of the bolt. Hand cycling seems to show better ejection but only live fire will tell for sure. It is certainly more difficult to induce a situation where the ejected round remains in the upper receiver. Before adjusting the ejector, if I racked the bolt with less than 50% strength, the ejected round remained in the receiver.

3. Feeding issues. This only occurred every so often, and was just when chambering the first round. I have not been able to induce a failure to chamber on the first round while manually cycling it, so I am not sure what the cause or solution for this one is.

4. Suppressor POI shift. No insight on this. Everybody I describe the problem to seems bewildered by it.

Here are some pictures I have taken:


Pic showing how close the ejector is now riding to the bolt. I am hoping this fixes my problems but we'll see.


Empty magazine


Loaded magazine...does it look like the feed ramp is off center? Is that normal?


Overhead view. Again it looks like the round is not centered over the feed ramp. Hard to tell though. You can see the ejector is bent to the right now.


Head on view


Close up of feed ramp.


Thanks for all of the feedback so far. I hope to make it to the range tomorrow, where I will test 115 and 147gr factory new ammo, both suppressed and suppressed, to narrow down any remaining issues.

-Twister

Sorry, I meant the ejector. The little sheet metal piece pinned to the receiver. The feed ramp does look to be slightly askew... could definitely be the problem. Ive had feed ramps that look spot on result in problems.

 as for the POI shift, if your barrel doesn't have an index point on it, is it possible that your barrel nut is not tight enough and your barrel is actually rotating?

Is there any way to shift the feed ramp? It looks welded in place...

The TROS barrel has an index 'pin' that fits into a corresponding slot in the receiver; there is no way it is rotating. Plus, that would imply that POI shift would occur unsuppressed as well and it hasn't.

-Twister

It's just pinned in place, without grinding on it, it is not adjustable

The only way to adjust your feed ramp is to grind off and weld on. I've never fiddled with the Glock lowers so I'm not really sure of the winning combo. Track down MadMachinist. He is a bit of an expert on these pistol cals.

As to your POI problem, I talked to my class 3 expert, he said its a very common problem and not an easy fix. Has to do with barrel harmonics, silencer weight, and subsonic variations. His reccomendation was to get yourself a bunch of different factory loaded ammo and see if you can't find one that plays well with your can. After that you can try a different attaching system like just threading it on if you are using a 3 lug now. The next steps would be trying out different barrels and suppressors.

RANGE REPORT

I started at 50ft, with factory new 115 gr, without the suppressor. I fired 7 rounds which were off to the left slightly but all in a ragged hole. I then fired an additional 7 rounds of 147gr new and they were in the same ragged hole. Both loads locked back on the empty mag - I think that problem is solved. The next group I fired was an 8 round group of 115gr with the suppressor. You can see the spread for yourself:



Next, I shifted my point of aim to the head, and fired 8 rounds of 147gr., suppressed. Same type of effect.



At this point I had no malfunctions of any kind, so I decided to try some of my re manufactured 115gr. I released the bolt, and immediately got this:


After pulling just slightly on the charging handle, the bolt went fully into battery. I pulled the trigger and was greeted with no reset. Stovepipe.


Two rounds later and I got an even nastier one. Here, you can see that a fresh round was in the process of being locked into battery when the bolt's forward movement was stopped by the partially ejected casing.




To conclude, I THINK the stovepipe issue has been rectified with new ammunition and the regular strength buffer spring. The  bolt would occasionally lock back with 1-2 rounds still in the magazine, but after adjusting the actuator tab, I nullified that issue for the remainder of the time. I think now the only issue remaining is the POI shift. As you can see it's quite significant.

I've tried a few different ammunition types and so far they all mimic the same type of pattern. An email response from Mark at TROS offered this:

"The only thing that makes any sense is that the bullets are SLIGHTLY touching the baffles or end cap.  The barrel nose may be slightly small or the mount may be slightly too big."

What do you guys think?

Is the remaned ammo all of the same headstamp? With AKs when I have that sort of extraction issue it is usually due to the extractor hanging onto the casing too tightly. I will remove the extractor and file off just a little bit to remove some of the material that is accounting for the bind.or replace the extractor. The other issue could be that the cases on the remaned ammo might not be resized properly. My point being that it could either be the the extractor may be undermachined or the remanufactured ammo may be flawed.

Back to the POI issue. Do you notice any material build up on the front end of your can? If not, I am guessing that contact is not the issue. If so, you might try a different three lug adapter that offers a tighter fit. That is something ive encountered before. I have really good results with fiocchi sub ammo in regards to accuracy. You might try buying a box or two of it along with some high end loads. If you see an improvement and dont want to pay the high price, buy yourself some equipment and start playing with your own loads. It could be a matter of getting just the right pressure that your suppressor is wanting.

Update:

I will be sending my TROS barrel back to Mark at TROS so he can make sure the tip of the barrel which contacts the adapter is in spec. If it is, which I am pretty sure it is, then perhaps the JB Tactical adapter is the problem. It's also possible that neither are the issue, as Derek84 mentioned, and that it's all an ammo thing. I'm not willing to succumb to 109543 ammo tests just yet, and Mark at TROS is in the same state as me, so I am going to send the barrel to him this week.

I am not seeing any buildup on the front cap of the can. I did however, notice a lot of rattling after the 100-150 rounds I fired the other day. So I disassembled the Ti-Rant 9 and found some interesting things.

First off, the can was really filthy considering I had just cleaned it a few hours before the range:



Second, the two baffles furthest from the barrel (so forward-most baffles) where a weird greenish tint and had lots of debris stuck to all sides except where the exhaust port is. I have never seen this before. You can also see the endcap has the green stuff with debris stuck in it, but it's only on one side of the endcap. The other 180 degrees is basically clean. Very weird.


Third, there was a ton of "frag" or shrapnel like debris throughout the can. It was not just carbon because it's sharp and hard, like fragments of a copper jacket perhaps? It's all black so it is hard to tell what the material is, but it's quite sharp and quite hard. Never saw this when using the can on my G19.


Thoughts? Is this indicative of something?

You have an accuracy problem with the suppressor attached, not a POI shift problem.  Semantics, but I think it is confusing people.

Here is a reply I got about my 9mm AR accuracy problem from a post I made on 6.8forum.  Doesnt apply to me, but seems very relevant to you.

Interesting. I think I just found the problem. I am not sure what the solution is.

It appears I AM in fact getting baffle 'nicks'. Not sure how I missed this earlier today. Check out the picture below. You can see the round is 'rubbing' on one side on its way out. This would explain the jacket frag. Anybody have an explanation as to why some of the baffles are whitish and some are the regular sooty color?



Here is a close up of the three worst ones. You can see the shiny portion of the baffle where the round was rubbing or partially striking:




Thoughts?

By your last pic, it looks like the barrel/mount is not concentric to the end of the suppressor. That is what is causing the crazy "grouping".
Saw the exact same thing with a bunch of SR25's with suppressors that the Rangers had at Ft Benning when I was there to work over their M82A1's.
They were shipping the SR25'S back to Knights because of the problem.

That's what I figured. The barrel and adapter are both going back to their makers to be examined. Hopefully one of them will have answers. The next question is, will the material in the baffles that's already been eroded cause an accuracy issue once the baffle strikes are resolved? Since gas could escape around the projectile perhaps? Just wondering if I'll need to contact AAC about baffle repair/replacement.

If Gemtech's new design doesn't cause problems I'm sure your slight erosion won't be a problem, the bullet is moving ahead of the gas and the baffles are further slowing the gas down.Gemtech's new 45 baffle design

Update:

Mark at TROS (3 lug barrel) and Ryan at JB Tactical (the 3 lug adapter for my Ti-Rant 9) have both received their respective components and inspected them. They both seem to be in-spec according to their measurements. This further baffles me (no pun intended). Clearly the problem is one of concentricity, so how could both parts possibly be in spec? Even more confusing is that Ryan at JB Tactical used my adapter on his own 9mm MP5 with his Ti-Rant 9 and had no issues. No baffle strikes, no wild groups either. Ryan is now mailing my adapter to Mark at TROS who has my barrel. Mark wants to take a look at how the barrel and adapter are linking up to see if he can figure out the issue. If he can't, Ryan has offered to look at the entire build free of charge. So worst case scenario is I get my parts back from Mark, and ship the assembled 'pistol' to Ryan for examination. Both Mark and Ryan have been exceedingly helpful and genuinely interested in helping me solve my problem. Big thumbs up to both of them for customer service!

Any more thoughts are, of course, welcome.

-Twister

ship it all to him and have him look at it