Extractor broke

[NoFail]

:'(

So serves me right for not having replacement spare on hand. I'm ordering two new ones to keep one spare.

The tooth at end broke clean off.

[98Z5V]

What BCG are you running?  This is in the JD build, right?

[ipsick]

The JP extractor broke?  Bummer and sorry to hear that NoFail.  Keep us updated.

[Robocop1051]

What were you doing when it broke? Rapid fire? Steel case ammo?

[NoFail]

JP enhanced bolt in the JD build. I was testing a Varget load, nothing hot at all @ 43 gn w/168 Amax.

It was going on 3:00 pm yesterday when I called JPE from the Left Coast, called from range immediately after I realized it. Chick took my # and said she'd have someone call back. It was going on 5:00 (I think) where they at so I was thinking they call back this morning. Still nothing so I'm gonna call again.

Also, since this has happened, I wonder if I just might send them the upper and have them remove barrel and re-torque for me. The guy who torqued it for me, same guy who lapped front end of receiver, torqued the holy hell out of it. I watched him do it and and when it got close and just had to clear a "spline" on the nut out of the way of gas tube hole he just kept torquing and torquing until clear. I asked how much torque on there and he said "I don't know". He was leaning on the long wrench bar big time. God only knows how much pressure and I'll never use that guy again.

So maybe I should just send it to the pro's and let them do it right.

Also Slash's CAR 10-XH buffer + JP LMOS BCG + adjustable gas block, I wonder if that is not good to mix those up? Maybe I should use new JP Silent Captured Spring? That's probably what JP would say, of course they would. But I dunno if the way I have it is not so good. Could be reason for broke extractor but who knows, I don't. Still though it always seemed to run good.

Edit; hmmmm but I'm running UBR I wonder if silent captured spring will even work in there... I'm calling them now I'll update here later.....

[survivalshop]

What was the round count on that extractor ?

[Robocop1051]

I'm wondering if the heavy buffer forcing the light weight carrier had some influence?

[ipsick]

I'm wondering if the heavy buffer forcing the light weight carrier had some influence?

I'd be interested to hear what JP would have to say about this.

[Robocop1051]

While looking at the JP website and the design of their rifles... The Low Mass Operating System appears to be dependent on the controlled gas. The LMOS isn't just the bolt carrier, but also the buffer system. By limiting the gas through an adjustable gas block, and then lightening the amount of weight being forced through the weapon cycle, you can reduce the recoil significantly. That was their ultimate goal.... However, they did this all at the cost of reliability! They even state that they do NOT put the LMOS in their LE/Combat rifles. This is strictly a bench gun/competition enhancement. They do not recommend using the LMOS when every single shot MUST count.

I think combining the LMOS carrier and the heavy buffer was an accident waiting to happen. They work fine together now... but buffer is easily 2x-3x the weight of the LMOS buffer. That is a considerable amount of weight behind skeletonized parts.

[Robocop1051]

Disclaimer to the above:

I do not own a JP Rifle, nor have I shot their products. I am, however, greatly impressed with their design and concepts. My opinion is solely based on my loose grasp of physics and novice level of knowledge towards AR parts and compatibility.

[ipsick]

I don't think you can be critical of the reliability of the JP LMOS system when the failure discussed in this thread could be due (as you have hypothesized) to using a component not proscribed in their system.

I realize their system might be a little more complex than a typical mil-spec system so the added complexity might open the door more for failure(s), but it is not a certainty.  I've seen plenty of mil-spec full mass setups fail at the range.

That being said, considering my own recent JP bolt issues (http://308ar.com/forum/building-a-308ar/bolt-lug-wear/) I can see some minor production issues due to the high demand.  Greater production volume might be leading to unforeseen qc issues.  JP finally resolved (replaced) my bolt after other customers were experiencing similar issues and determined a few bolts got out without the properly specified hardness.   

[NoFail]

I received two new extractors from JP, one on warrenty and bought an extra. Guy from JP I talked to last week, apparently a engineer, was cool and could offer a failure mechanism, but didn't hesitate to warranty for me.

I told him I'm using the CAR 10-XH buffer and he didn't have a bad reaction to that. He said that it probably slams back forward pretty good. He said if I wanted I could just swap a stock carbine buffer and spring in there.

And I was concerned that my barrel nut has ish loads of torque on it but he said it's a non issue. I said there could be 150 lbs on it but he said it is okay and won't harm anything and he doesn't think mil spec is enough.

Anyway I'll run new extractor and if it breaks later I'll probably go with different buffer in the UBR. She was running good before it broke.

[carbon9]

The JP Silent Captured Spring will work in a UBR, I have one in mine along with the JP .308 LMOS and it is working great.