Issue with rifle surfaced during training course, report

AR/M4 AR Technical Discussion
1

I wanted to start this thread to provide everyone with my experience with certain parts that went into my AR15 and issues I had with them. I just took Viking Tactics Basic Carbine course (first course) and a couple issues surfaced.

Info on the rifle:
Upper: N4 Light Recce Low-Profile 16" Upper
Lower: Noveske 2nd run stripped
LPK: Daniel Defense
Other misc parts: BCM gunfighter charging handle-large, replaced noveske bolt with BCM bolt, used a MOE grip instead of A2.

I assembled the lower myself with the help of the error-net. I went slowly and the rifle passed all function tests. Test fired at range with only two rounds in magazine to insure any doubling, trippeling issues would not get anyone killed.

The first issue was the selector. I read that it should work the same when the BCG is locked to the rear as when it’s in battery. This was not the case. It was much more difficult to operate when locked to rear but possible. Also when going from safe to semi the selector was fine and relatively easy. But going from semi to safe (with BCG forward) took much more pressure. Someone told me a quick fix was to put some grease in the channel the detent runs in which I did. After the grease it worked well (until the end of the two day 1200 round class, more later).

The second issue would surface at the VTAC class. At the class every time we would go hot I would start with the BCG locked to rear, insert a fresh 30rnd pmag and hit the bolt release. The round would barley start into the chamber and stop. I could get the BCG into battery by simply banging on the bottom of the pmag vigorously. A couple good whacks and the BCG would fly home chambering the round. The gun was properly lubricated with a generous amount of SLIP 2000. The same thing would happen when the BCG was in battery on a empty chamber and I inserted a full 30rnd pmag and ran the charging handle (by the way I was insuring the pmag’s were seated properly and wasn’t ridding the charging handle). I experienced zero failures to feed (other than above mentioned), extract, eject, etc.

The bolt catch had an indention, scratch or gouge in it and seemed to be wearing faster than I would think would be normal. Dan from VTAC looked at it and observed my failures to feed and thought that it may be an issue with the bolt catch spring. Whatever was causing it, it was clear the bottom of the BCG was dragging on the top of the bolt catch. He slapped his lower onto my upper and I put in a fresh 30rnd pmag and it worked perfectly. He suggested that I file the top of the bolt catch down. When I got home I filed it down and got it to work properly.

By the end of the second day my safety was getting more difficult to operate from semi to safe. When I got home and replaced it I found that all the carbon had gunked up the grease (as expected). After all the grease was a temporary solution to the problem. I replaced the selector with a G&R unit and it worked excellent. It went from safe to semi and back with the same amount of gentle force. I locked the bolt to the rear and operated the selector. I could not tell a difference. It was great.

I then replaced the bolt catch assembly with a G&R unit and it dropped in with a better fit (less front to back wiggle) than the DD unit. It also worked properly the first time as it should with a 30rnd pmag. While racking the charging handle the action also seemed smoother and to spring back into battery more vigorously. I attribute this to the old bolt catch putting constant pressure on the bottom of the BCG.

I am not trying to bash Daniel Defense in any way. I’m just reporting what I found to be the case with my particular rifle.

By the way the class was excellent and I will definitely be taking more classes from VTAC.

My camera is dead and the charger is MIA. If I can find it I’ll take pictures of the parts in question.

Thanks for reading, hope this can help someone some time in the future.

2

Is this your first AR?

3

Yes it is.

4

Do you have any friends you could swap uppers and lowers with?

5

I know a few guys with AR’s. Since everything appears to be gtg now what would swapping uppers and or lowers do? Are you saying put my lower on someone elses upper and see if we can create the same malfunction?

6

For startes, yes.

It also sounds like your hammer is dragging on the bolt carrier.

7

I guess I got eager to fix it and didn’t stop to think about what you advised. Is there a way I can test the hammer drag you mentioned? Thank you sir.

8

FWIW I use Colt bolt catches, mag releases, fire control selector, and trigger assembly.

Ive had too many problems with aftermarket LPK’s with quality and fitment issues.

One of the pluses to buying a complete rifle is the rifle should be function tested before it gets to your hand so bad parts shouldn’t make it to the consumer. In the case of assembling your own lower those potential bad parts will not be found out until you are on the range.

In the future I would also recommend not using an expensive class to test your rifle. It would be a good idea to have at least 500rds through the gun before hand, and any issues worked out before you show up. That way you are not wasting your class time, and the instructor’s time trying to diagnose a problem gun.

9

Isn’t the hammer supposed to drag against the BCG? If there is a doubt then go ahead and replace the hammer and probably the sear.

From what he posted, it sounds like an out of spec bolt catch and safety lever (LPK).

If it is doing what it’s supposed to be doing, then I would not worry about it. YMMV.

10

My home built lower using quality parts and an LMT upper runs flawlessly, but the safety selector is a bit harder to operate with the bolt locked to the rear than when its in battery.
Its not much harder, but it is a noticeable difference.

Is that a problem? Its never caused any type of malfunction.

Sorry to hijack, but it seemed like a good thread to ask in.

11

Regarding taking up instructors time at classes. Luckily the only time I took from the instructor was on the breaks. I did put a couple hundred rounds through the rifle before the class but did not experience the issue (because I wasn’t loading the mags fully) and therefore thought my rifle would be ok. However you are correct, it was a miscalculation on my part but luckily it didn’t cause any problems.

JBecker72,

I think the selector should work as I mentioned, the same in battery as locked to the rear. I will of course defer to a more experience mind on that.

12

Interesting thread… I’m doing the same upper on the blem lower w/ a CMMG LPK later tonight.

I’m also curious to see if the saftey will move w/ the BCG locked to the rear… in all the years I’ve spent w/ an AR in my hands I don’t think I’ve ever tried that one.

Regarding the bolt catch, I would have tried a USGI mag before I took a file to it. It sounds to me like the PMAG might have been the culprit. My original batch PMags were tight in my lower and non-DF. I also had the idea that the catch was improperly located b/c you had to slap them to death to get them to lock. I later ran them in a SAW on the range and it chewed the lips.

Not too scientific, as I wasn’t going to use them outside the gate…

I’m a WECSOG master, but I always try every possible configuration to diagnose a problem before I remove metal from a gun.

13

Same Serpico1985 from M14tfl.com?
I would try different mags in the rifle and see if that fixes the problem. I’ve had some mags that would work in one rifle and not in another. Your lower may hold the mag slightly different than the instructor’s causing drag while chambering a round. Also, more lube and an un-notched hammer may help. I can’t help you out with the selector.
Dustin

14

None of my AR’s have any issues rotating the selector with the bolt locked back. This is with Colt and KAC/LMT selectors.

15

Same here; LMT Complete Lower with Noveske Light Reece Upper and complete Noveske Recon…the Selector works in any position of the bolt.

16

my selector is the same way, it is just a little bit harder to rotate with the bolt locked to the rear. :confused:
it has over 2000 rounds through it.

17

Pezboy, I am on M14TFL as same name. I tried a couple of usgi alimnum mags at the class too and the rifle did the same thing. Although I should have tried a few more mags just to be sure. Instructor initally thought the same thing as yall about pmags.

Well, whatever, it’s fixed now, just have to take it to the range to be sure.

I didn’t know if anyone else had any issues with the Danile Defense parts kit or if I was solo on that.

Camera battery still MIA. I’ll see if I can use my camera phone to show wear.

18

I feel like I owe you an apology! Although I didn’t say anything about it yesterday, I was thinking that perhaps the safety was not fully inserted (i.e. selector side gap) but since you would come up way short on the other side I didn’t want to insult your intelligence. (I was thinking the detent wasn’t riding in the proper channel)

Last night I had the EXACT same problem! Upon completion of assembly w/ a CMMG LPK, functions check allowed the safety to move from SAFE to FIRE with normal effort, but it almost wouldn’t go back to SAFE after I thumbed the hammer back. Upon examining the part, I’d say that instead of the little dimple to allow the detent to rest, this selector had a pretty large, deep recess.

Luckily I had a spare Stag selector and detent, which I replaced them with and everything was perfect after that.

I wonder if there is a batch of horribly out-of-spec selector levers going around?

19

There is some conversation on AR15.com about this very issue, there seems to be a problem with the CMMG LPK, in specific the safety selector.

20

There is some conversation on AR15.com about this very issue, there seems to be a problem with the CMMG LPK, in specific the safety selector being out of spec