What is the length and tolerance of that length, of said bolt-lug? I have a bolt that is “sticky” when I administratively clear the weapon (requires a weak mortar or a good YANK! on the CH).
More likely an ammo or barrel/headspace issue… assuming the bolt is a known/good brand.
Is it factory loaded ammo?
-Speer LE Gold Dot 64gr.
-Neither the Daniel Defense Bolt nor the Noveske bolt, in their respective guns, have this issue. This bolt does in both.
-The bolt lugs measured around 0.280" in length with my calipers. I need to measure the Noveske/DD bolts, but did not. I do not wish to discuss where the bolt came from at this time.
Try the DD or NOV bolt in the problem gun. 
Doesn’t seem like the ammo… that’s good stuff.
I had one recently where the extension was slightly misaligned and had issues with certain bolts that wouldn’t go into battery. I tested three bolts and only one would go into battery smoothly. That one also had the thinnest lugs, measured at 0.100". The other two had slightly larger lugs, with one feeling sticky going into and out of battery and the third would not go in at all. The one that would not go into battery was NiB coated and measured 0.103". That bolt inserted fine into other uppers. However, the additional bolt lug width combined with a slightly misaligned extension, was a no-go.
I say all that just to point out that it could be the lug length, width or extension alignment (less likely). Do you have any other bolts that you can test in that upper and then compare dimensions with your problem bolt?
They are all problem guns. Both of them (dd and noveske) get sticky when this bolt is used.
Lugs miced 0.98"
Both are complete guns from dd and noveske. Neither have issues with multiple other bcg. I mainly want to know what this bolt should*** measure, and how much leeway spec allows. I’ll measure the dd bolt when I get home.
So the problem bolt lugs measured 0.098 x 0.280"?
I’ve got a couple of low round count BCM bolts at home. I’ll try to measure them tonight for you. I’m not sure what the specs are, but maybe we can establish an estimate for you.
Correct, and thanks!
In the past 2 weeks I’ve never heard of so many headspace and tight lug issues on AR15’s. It’s everywhere and enough that its strange.
The one common theme is a no-name (claimed to to mil-spec) obviously not mil spec bolt. Just an observation.
Just to be clear, my issue was not a fault of any of the bolts tested.
This bolt needs to be guaged in a barrel too. It may be that the bolt face is cut too shallow.
It’s not just on the interwebs.
I’m even having friends that have come to me in the past couple weeks with the same issues. My BCM bolt would resolve the issue. It just strikes me as weird or maybe its a big coincidence.
Not coincidence.
I could see this coming months ago. In a rush to bring any and everything to market, this kind of thing was inevitable.
On my Colt bolt, all the lugs were about 0.100" x 0.278" x 0.177".
The overall width of the bolt was 0.739" measured at adjacent lugs. Obviously the extractor side would measure different. Overall length is 2.800".
Bolt has a couple of thousand on it.
I don’t know what the big secret is in not listing the brand. I’d want to keep other guys from buying crap, and these things tend to run in batches.
The Daniel Defense bolt (came with the gun, works fine) measures 0.102" across the lug, and 0.275 by the length of it. This is compared to 0.98" and 0.280", respectively, of the offending bolt.
I suspect it’s not a lug problem, the lugs don’t have that snug of a fit with the barrel extension. It could be an issue with the cam pin hole as to its position. Without comparing the suspect part with a known good one, its hard to say.
The rules here are to contact the company first. I have now done that.
Rubber City Armory originally, upon hearing my issue (but no measurements) stated that while they would do whatever I wanted (refund, swap out, etc.), I might be best to “just write them off”, and that perhaps I and others like me were “picky”, as most of these types of returns “work just fine” in their guns. I was informed that AK-47’s have a lot of slop and can work with a lot of gunk in them and that I may be better served to consider one.
Upon hearing the measurements of 0.280", they agreed that this was a little off and seemed more inclined to my way of thinking.
I had agreed to send in the bolt for a swap…
…but after a good hard work-out this AM, and thinking about the things that have transpired, I decided against returning the bolt for a new one as I had discussed on the phone.
The carrier is nice, and I’ll keep it. Bolt can go in the trash. I would rather run a known quantity from BCM or Daniel Defense, as I have literally never before encountered a bolt out of spec to the point that it caused administrative unloading of the weapon to require goodly effort. (Feeling like trying to extract brass-case after shooting a lot of steel). Chamber is not the issue as my other bolts work fine, including one of the previous one’s from RCA. Their products seem to be “all over the map” when it comes to machining, and I’d just rather not.
Interesting idea. I hadn’t thought of that.
The rule about contacting the company has nothing to do with disclosing their name. It’s to keep someone from bad mouthing a shop without giving them the chance to rectify the problem.
Again, I really doubt this is a lug dimension issue. They just don’t fit that tightly. I really suspect this has more to do with how the bolt is timed, ie its not in its fully unlocked position when it should be.
As for the bolt face idea, is this only when ammunition is present? Or does it do it when retracting on an empty chamber?