I could use some diagnosis help, please.

[DustinIL]

Hello all. I haven't posted in a long time, but have lurked now and then.

As the title states I could use some help with diagnosing a couple issues with my Franken-build .308AR. I was hoping I had done enough research to avoid a post like this, but nope. I apologize if this post becomes long winded, but I wanted to make sure as many details are listed as possible for best educated guesses/diagnoses. So with that said I will list the parts I used for my build for background:

Upper:  Guntec USA (DPMS-style low, lightened with cutouts, Gen 1?)

BCG:  Brownell's, BRN-10 chrome

Charging Handle:  ZEV Technologies

Handguard:  Midwest Industries, MI-308SS15-DLM

Lower:  DPMS

Lower Parts Group (minus FCG):  DPMS

FCG:  ALG Defense ACT

Stock/Buffer tube:  ERGO F93

Buffer spring and buffer:  unknown make/model bought in a kit (https://bkingsfirearms.com/shop/ar10-spare-parts-lower-parts-kit-upper-parts-kit-and-triggers/ar-10-308-six-position-buffer-tube-kit-w3-8-oz-buffer-mil-spec/)

Barrel:  Ballistic Advantage 16" Hanson profile, using their low-pro gas block and gas tube

 

After buying parts during the course of a couple years (waiting for sales, etc.) and having parts Cerakoted, I finally put it together a couple months ago and did the barrel break-in per BA's instructions a couple weeks ago. NOTE:  to make the handguard fit how I wanted (none of upper receiver threads showing, which can happen with some brands of uppers per MI's website, which I didn't know until first "mock up" assembly) I took it to a gunsmith and he removed just enough metal from inside the barrel nut to make it fit flush with the upper receiver and just enough metal from the top of handguard to match. After this was done everything went together just fine.

ISSUES encountered:  About half-way through the barrel break in I felt something touch my nose, and immediately checked the charging handle. Upon inspection I saw that the "shelf" that the CH "claw" rested on had been work, considerably (see pic). To be honest I only got the ZEV because it was an ambi CH for a reasonable price and because I couldn't find a BCM one at the time. Also, while looking closer and the ZEV CH's claw profile, I noticed that its profile is different than other CHs I've used/seen (see pic). Even with the different profile, I wouldn't expect the CH to go back with the bolt even everything as was running right, but I don't know what I don't know about .308AR particulars. Also, I noticed that the handguard had started creeping forward as well; simple fix I thought by re-tightening the two screw at bottom of handguard (the screws were torqued beforehand per MI specs). Nope, handguard creeped forward again.

So dear readers and Wizards of .308AR Smart I come to you for help. Does the ZEV CH just have a bad claw design and therefore was destined to now work like other CHs (I did finally score a BCM charging handle after this, and it has the more "traditional" squared claw), or should it have worked correctly and something else is causing it to be forced back (over-gassed, gas leak, etc.)? I saw no abnormal wear on the CH or inside the upper that isn't out of the ordinary during typical use, especially after being racked a few times during assembly, etc.

As for the handguard, I did email MI yesterday to pick their brain. Guy I was in contact in is thinking I might have not used enough of the bedding compound (Vibra-tite 548) that came with the handguard. To be fair they didn't say how much to use so too little use is definitely a possibility on my part, and possible need to score up the inside of the handguard that goes over their barrel nut for more surface area. With that, any suggestions on how to remove dried up bedding compound so I can apply a new layer of Vibra-tite, or do I try just getting more and putting it over bare spots and what's already dried on it? I responded to him that I'd check what he suggested, but the main issue I'm having with the HG is that when I tried to put it back on, when having it lie on a flat surface to make sure the upper and HG are square and flat with each other, when I start to tighten the two screws, and it doesn't matter which one, it causes the muzzle end of the HG to rise. I did NOT have that issue when I first put it together; not sure if i hand tightened the screws too much at the range (didn't have my torque wrench with me) or what.

Again, my apologies for this novel. I have tried scouring posts here to find similar issues, but no luck so far. I hope they're simple fixes, but with me being a tad frustrated that I couldn't figure it out yet has my mind going down the rabbit hole and assuming the worst that I have to buy new parts and basically rebuild the thing.....sigh.

I can't give any other detailed pics at the moment (at work), but can try to take some later, family time willing this weekend. If not then, for sure Mon. or Tues.

Thanks again for sticking with me this far and for any/all help offered.

 

[washguy]

Dustin heres just one review of the Zev     throw that piece o crap away ...yes bad design.....on the Midwest rail....that's the one reason I never used one of those because of it showing threads.... ive used many Midwest rails in the past,but with all these new cheaper rails that are good quality ive not used Midwest in a long time.....when someone starts screwing with the tolerance's  of the upper and the barrel nut I go whoa !      Wash

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1

Rated 1 out of 5 stars

Not recommended

Submitted 5 months ago

By Gator

From Georgia

Verified Buyer

Comments about ZEV Technologies Slidelock Ambidextrous Charging Handle AR-15 Aluminum Matte

Purchase this charging handle because I liked the idea it was marketed for less moving parts. After about few rounds I noticed a deep groove into the forged upper where the charging handle latches. I called Zev/ Technologies sent them a picture of the upper receiver with the deep groove cut into the latching area on receiver and advised the spring tension was excessive and was told it look like normal wear and was basically blown off by the tech. I read comments that said only use on billet receiver's tech said it didn't matter. Maybe I got a bad one but they didn't offer to replace it. One star!!!

[98Z5V]

7 hours ago, DustinIL said:

 With that, any suggestions on how to remove dried up bedding compound so I can apply a new layer of Vibra-tite, or do I try just getting more and putting it over bare spots and what's already dried on it?

Virba-tite is a different kind of thread-locker.  It's not at all like Loc-Tite, with many of the Loc-Tite types that dry and "lock" the threaded parts together.  They get all crusty when you take them apart.  You can use Vibra-tite over and over, without reapplication, because it never really "dries."  That the awesome part about using it on firearm's applications.  I mainly only use it on scope mounts, bases and rings, and use the Vibra-tite VC-3 compound.

That 548 you're using looks like it bonds cylindrical fittings - not really a threadlocker.  If that's the game, then use Loc-Tite 609 for that job.

[DustinIL]

12 hours ago, washguy said:

Dustin heres just one review of the Zev     throw that piece o crap away ...yes bad design.....on the Midwest rail....that's the one reason I never used one of those because of it showing threads.... ive used many Midwest rails in the past,but with all these new cheaper rails that are good quality ive not used Midwest in a long time.....when someone starts screwing with the tolerance's  of the upper and the barrel nut I go whoa !      Wash

Flag this review

 

 

 

 

 

1

Rated 1 out of 5 stars

Not recommended

Submitted 5 months ago

By Gator

From Georgia

Verified Buyer

Comments about ZEV Technologies Slidelock Ambidextrous Charging Handle AR-15 Aluminum Matte

Purchase this charging handle because I liked the idea it was marketed for less moving parts. After about few rounds I noticed a deep groove into the forged upper where the charging handle latches. I called Zev/ Technologies sent them a picture of the upper receiver with the deep groove cut into the latching area on receiver and advised the spring tension was excessive and was told it look like normal wear and was basically blown off by the tech. I read comments that said only use on billet receiver's tech said it didn't matter. Maybe I got a bad one but they didn't offer to replace it. One star!!!

Hey washguy, thanks for the response. Yeah, I probably should have looked further into the ZEV; silly me thinking ZEV was a decent company and I got it for a reasonable price IMO. Well, according to the packaging from the upper receiver I used it says it's billet so I don't know. I've already swapped it out for a BCM I was able to find and the ZEV will go into the "Bin of Misfit Parts". Next day off I'll have to try the BCM and see if it comes back during firing.

But the question remains, is the ZEV's latch design flawed and therefore would come back during firing no matter what, or is there still possibly an issue pushing it back?

As far as the MI rail goes, I like the feel of it; it's lightweight, slim enough for me to get a comfortable grip, and plenty of places to put rails. BUT, MI should have put the issue with threads possibly showing depending on upper brand on the actual page of the rail itself and also on the packaging with the instructions, not somewhat hidden on their FAQ page. IIRC only about 1/16" was need to be removed from inside the barrel nut and pict rail on top for it to fit flush, so not really a deal killer overall, and I don't think its structural integrity was compromised. But, would have I bought it knowing ahead of time the thread thing? Doubtful. Again, like the ZEV, bought it for good price on Black Friday sale and from a reputable company.

And question remains with it: why does the muzzle end now raise up when I tighten the rail screws when it didn't do anything like that the first time?

[DustinIL]

11 hours ago, 98Z5V said:

Virba-tite is a different kind of thread-locker.  It's not at all like Loc-Tite, with many of the Loc-Tite types that dry and "lock" the threaded parts together.  They get all crusty when you take them apart.  You can use Vibra-tite over and over, without reapplication, because it never really "dries."  That the awesome part about using it on firearm's applications.  I mainly only use it on scope mounts, bases and rings, and use the Vibra-tite VC-3 compound.

That 548 you're using looks like it bonds cylindrical fittings - not really a threadlocker.  If that's the game, then use Loc-Tite 609 for that job.

Hey 98Z5V, thanks for the response. You are correct on the application of the Vibra-tite VC-3 and 548, and Loc-Tite. I didn't use the MI supplied Vibra-Tite 548 on the two screws to attach the rail, only on the surface of the barrel nut as per MI's instructions. I used blue (medium) Loc-Tite on the screws. Is dried 548 as easy to remove as VC-3, or do I have to do some light scrapping/chipping to get it off? Or can I apply another layer over the dried stuff and it'll still work, like when reapplying VC-3?

[mrraley]

I do not have experience with the vibra-tite, but the easy way to get rid of loc-tite is heat.

 

I use a propane torch and lightly heat it up without overheating the metal parts.

When the lic-tite breaks loose, you'll know. You'll get a sweet smell. But act fast, cause if it cools before you get it out, it will reset and you'll have to do it all over again. 

If your screws are out, heat them and wipe them off then brush with lacquer thinner to clean any residue. 

[Belt Fed]

The charging handle is a piss poor design, as mentioned throw that crap away. it should lock up and stay locked no matter how much the carrier pushes on it. May be the angle of the pic, but it looks like it has buggered up the latch indent where a squared off latch may not hold good.

[DustinIL]

3 minutes ago, Belt Fed said:

The charging handle is a piss poor design, as mentioned throw that crap away. it should lock up and stay locked no matter how much the carrier pushes on it. May be the angle of the pic, but it looks like it has buggered up the latch indent where a squared off latch may not hold good.

It has indeed rounded the outside of the latch indent. That's when I looked at the design of the ZEV latch and its angles on front and back, vs. a more traditional style latch with the more square/90* profile like a BCM or mil-spec type. Oddly though, when I first had the rifle completely built I did have to use a little oomph to rack it for function checks because the ZEV's latch doesn't use a rotation pin to help unlock the latch.

Assuming everything on my build is in spec and running fine, i.e. not over gassed, no parts binding etc., would the ZEV worked fine and not be forced back, or is there an issue somewhere that caused the ZEV to be pushed/pulled out of lock and hence wear down the CH ledge of CH indent?

[Belt Fed]

If your brass looks fine, no blowed out primers or rims tore off or even excessive recoil i'd say it was the latch design that failed. Pretty sure every time you charged the rifle with that rubbing the indent it finally wore enough where it wouldn't hold. A horrible design.

[DustinIL]

11 minutes ago, Belt Fed said:

If your brass looks fine, no blowed out primers or rims tore off or even excessive recoil i'd say it was the latch design that failed. Pretty sure every time you charged the rifle with that rubbing the indent it finally wore enough where it wouldn't hold. A horrible design.

Good point about the brass. From what I remember I didn't see any issue with the brass when I picked it up, but I'll take a look at it again when I get home to confirm. I used a mix of some milsurp and commercial for the barrel break-in; they all felt the same and "normal" for a .308 to me.

Edited April 21, 2019 by DustinIL

[DustinIL]

Charging handle UPDATE:

Finally got some spare time the last couple days to look the rifle over and look for any other signs of what could be going on with the charging handle coming back. I took the upper half off, turned it upside down, and moved the bcg back and forth by hand. No signs of the bcg dragging/binding on the charging handle. No signs of wear at all on underside of charging handle where gas key goes. Also no signs of abnormal wear on the top of the charging handle where it goes against the upper and vice versa. After moving the bcg back and forth by hand and with a varying the speed of movement, I noticed that the back of the gas key is striking the back end of the underside of the charging handle. I put a little bit of white touch-up appliance paint on back end of CH and moved the bcg back and forth again; noticed two small marks in paint. This point I decided to take the rifle and 10 rounds to the range and just watch the charging handle as I fired. As expected the charging handle came back a couple inches 6-8 times. I pulled the rear pin and checked the paint on C.H.; same two marks.

So with that said, what are my options to fix it? With no standardization with 308 ARs do I try another brand of CH (with longer recess for gas key to travel, if available)? Different buffer weight, spring, both? By chance the gas key on the Brownell's bcg bigger/taller than others? Or is there something else I should check first?

 

Midwest Industries Handguard update:  after a helpful discussion with Andy from M.I. and obtaining some more Vibra-tite 548 (bedding compound) and a small torque plate for the handguard screws, I cleaned off the old 548 and applied again more thoroughly, used the torque plate and reinstalled. I let the 548 cure completely without doubt and to check to see if it moved during the 10 shots mentioned above I put a mark an indexing mark on it with sharpie. I'm happy to report that the handguard didn't move this go-round. Once I get the CH figured out (I really, really, really hope that it's not the upper receiver at fault) the next step is to do some groupings and hopefully run it in a training class to so if it's truly GTG.

I would definitely like to give a shout out to M.I.'s customer service and Andy in particular. I'll make a post about it soon.

[98Z5V]

11 hours ago, DustinIL said:

 After moving the bcg back and forth by hand and with a varying the speed of movement, I noticed that the back of the gas key is striking the back end of the underside of the charging handle.

Pics of this contact will help.  I've never, ever seen a gas key hit a charging handle.  Gas keys are all the same, AR15 and .308AR, there is zero difference in them.  This leads me to believe that the charging handle isn't machined the way it should be.  Pics, again, will help. 

[98Z5V]

On 4/20/2019 at 10:26 AM, DustinIL said:

As the title states I could use some help with diagnosing a couple issues with my Franken-build .308AR.

Charging Handle:  ZEV Technologies

I think I found your problem:

 

[98Z5V]

Further research reveals that this is an issue with wear on upper receivers - otherwise, ZEV wouldn't make this expensive billet upper receiver that combats the wear of their charging handle - this is a specifically machined upper, that takes a threaded steel pin, on the charging handle lock on the upper:

A steel pin is inserted through the rear of the upper for the charging handle latch to lock onto. This resolves a wear-and-tear point on the MSR platform by replacing aluminum with steel. Replaceable steel, at that.

Here's where I gleaned that information:

https://www.thetruthaboutguns.com/2017/10/jeremy-s/new-zev-tech-ar-15-ar-10-rifles-components/

A little bit of research looks like it solves this issue.  The issue is your charging handle. 

 

[DustinIL]

17 hours ago, 98Z5V said:

Pics of this contact will help.  I've never, ever seen a gas key hit a charging handle.  Gas keys are all the same, AR15 and .308AR, there is zero difference in them.  This leads me to believe that the charging handle isn't machined the way it should be.  Pics, again, will help. 

 

15 hours ago, 98Z5V said:

Further research reveals that this is an issue with wear on upper receivers - otherwise, ZEV wouldn't make this expensive billet upper receiver that combats the wear of their charging handle - this is a specifically machined upper, that takes a threaded steel pin, on the charging handle lock on the upper:

 

 

Here's where I gleaned that information:

https://www.thetruthaboutguns.com/2017/10/jeremy-s/new-zev-tech-ar-15-ar-10-rifles-components/

A little bit of research looks like it solves this issue.  The issue is your charging handle. 

 

First of all, your Google-fu is better than mine 98Z5V. I have no idea why my searching for an answer didn't find this. Thanks.

Second, I failed to mention in my last post that I had swapped out the ZEV for a BCM. Now, is the BCM also a bad design? Highly unlikely, but possible. Or two different charging handles with the same result indicate an issue elsewhere?

Apologies for the lack of a pic. I'll try to post one tonight or for sure tomorrow.

Edited May 9, 2019 by DustinIL

[DustinIL]

Current update:  I went ahead and bought a new buffer and buffer spring after consulting with Clint from www.heavybuffers.com. According to usps.com it was delivered today. Not sure I'll have time tomorrow to try it out.
 

But with that said, after reading up on the pinned posts about all the particulars regarding .308 ARs/AR-10s, is it possible that the gas tube I used is incorrect (too long)? Before coming here, I just realized I've never seen a gas tube labeled as AR15 only or AR10/LR308 only; just gas tube by length (pistol, carbine, mid-length, intermediate, rifle).

I'm just starting to doubt myself on just about everything with this build (except the lower, I guess). Silly me, when I first started to buy parts to build my first .308 AR, thought the main differences between the top two contenders (AR-10 vs. DPMS-type) were the shape of the upper receiver and the magazines used. Holy crap was I wrong.

Apologies for the lack of pics. Since all this began I've been working as much OT as I can get and also remodeling my basement on days off, so not too much spare time.

[Armed Eye Doc]

Glad you are getting it set up finally.  Let us know how it works out.

[DustinIL]

Does it look like the gas tube is right length or tad short?

[98Z5V]

Almost perfect.  It's a little on the short side, and should end directly in the center of the cam pin cutout.  If you switched that over to the Armalite AR-10 gas tube, it's gonna be another 3/16" longer. Find out where another 3/16" will put it; measure that out and check it.

[DustinIL]

On 5/23/2019 at 8:40 PM, 98Z5V said:

Almost perfect.  It's a little on the short side, and should end directly in the center of the cam pin cutout.  If you switched that over to the Armalite AR-10 gas tube, it's gonna be another 3/16" longer. Find out where another 3/16" will put it; measure that out and check it.

Sadly I didn't have time over this past weekend to measure or try out the heavy buffer and spring.

But I do have a question: During the roughly 60 or so rounds I've put through it so far I didn't have any issues of short stroking, which according to this thread, https://forum.308ar.com/topic/16799-gas-tubes-and-barrel-gas-ports/, could be a symptom of a too short gas tube. Granted, my tube isn't nearly as short in the recess as others are. I'll still try to measure on my next day off, but I was just wondering.

Thanks again.

[DustinIL]

I was able to go to the range real quick to try the new heavy buffer and spring and.......no change. Charging handle still comes back; not every time, but at least half the time. At this point I'm about to kick it to the curb. I even tried two different and new charging handles and still happened.

I didn't feel any difference in recoil impulse with the new buffer and spring vs. the lighter one I have. All brass ejected just fine and bolt stayed back on empty mag. When I got home I didn't break it down to see if anything had rubbed due to being in a sour mood. Will try to take a look next day off.

Short of taking it to a qualified gunsmith, any suggestions?

[Robocop1051]

I think your carrier is out of spec. The carrier is contacting the charging handle just enough to keep the CH in line with it while cycling. 

This could be from upward pressure, or out of spec area around the circumference of the carrier. 

Try a borrowed BCG, or at least a carrier. 

Also try single loading one round, and firing with no magazine in the rifle. 

Both of these are rare, but we need to eliminate everything. 

[DustinIL]

1 minute ago, Robocop1051 said:

I think your carrier is out of spec. The carrier is contacting the charging handle just enough to keep the CH in line with it while cycling. 

This could be from upward pressure, or out of spec area around the circumference of the carrier. 

Try a borrowed BCG, or at least a carrier. 

Also try single loading one round, and firing with no magazine in the rifle. 

Both of these are rare, but we need to eliminate everything. 

Good ideas Robocop. Out of curiosity are the specs for the BCG in a thread here so I can at least use a micrometer on mine? (Looking now too for specs)

[Robocop1051]

I don’t think anybody’s posted anything recently… But I’m sure a web search will come out with a blueprint somewhere. Borrowing somebody else’s, and just comparing the two, might be your best resource… Hell just take your carrier into the LCG and asked to compare against one on the wall

[98Z5V]

We did a ton of BCG measurements in a thread here, and I can't find the damn thread to save my life right now.  You should use that thread for reference - if it can be found...  

EDIT - here's the thread with the BCG measurements, and a ton more info:

 

Edited June 15, 2019 by 98Z5V