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Prepped .223 brass drops into JP case gauge--but sticks in chamber


Kasteel

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This has me baffled. To make a very long story shorter, I had issues setting up Dillon carbide full-length sizing dies in my Dillon Super 1050. I set up according to instructions, but even though sized cases would drop into the Dillon case gauge, when I tried the cases in my various guns, the cases would stick and require "mortaring" to dislodge the case from the chamber.

After plenty of research on these forums, I discovered that even un-sized cases would often drop into a Dillon case gauge, and that a "chamber checker" was necessary for my purposes. I bought one from JP Enterprises: the JP .223 Precision Case Gauge. The instruction sheet to that piece of equipment states: "If your ammunition fits flush in this case gauge, it will go into battery AND EXTRACT WHEN NECESSARY in any rifle." (Emphasis added.)

Here is my problem: my sized cases are dropping into my JP Gauge very, very nicely, but the cases are sticking in the chambers of three of my ARs. Two of the guns have Wylde chambers, and one has a 5.56 NATO chamber.

The instruction sheet makes clear that even if a sized case will not drop into the gauge, it might well still function in some guns, but if the ammo drops into the gauge, it should function in anything. Well, just like the late-great Waylon Jennings sang: Wrong!

So, my question is NOT how to get my ammo correctly sized. I'll bust out the magic marker and start coloring my brass to sort out what the issue is. I'll play with my die adjustment and have the thing machined down a few thousandths if necessary.

My question is, I thought the JP Gauge was the be-all-end-all-fool-proof device to avoid "oh shits." Apparently not. What am I missing here? What, exactly, is the point of this (fairly pricey) trinket? Given my experience, is the only option to remove the firing pin from your BCG and actually cycle sized cases and/or ammo through your gun? I was really hoping the JP gauge would get me out of that.

Any insights?

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As to trim length: All brass is trimmed to 1.750" or less and gauges OK.

As to OAL: OAL of loaded ammo is 2.255" or less (all fit in PMag) and empty, sized cases are still sticking in chambers--not just loaded ammo.

Still scratching my head.

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Those chamber checkers are hit or misses. You need to fire some cases from your rifles and use the RCBS Mic or the Hornady mic to measure the brass and set your dies.

http://www.midwayusa.com/product/477756/rcbs-precision-mic-223-remington

http://www.midwayusa.com/product/479704/hornady-lock-n-load-headspace-gage-5-bushing-set-with-comparator

Or you can keep on screwing down your die until the cases stops sticking in all of your rifles.

Problem with this is you don't know if you have overdone it until you fire the rounds.

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It stresses the cases more. If you keep on firing, resizing and reloading rifle cases, eventually the brass splits into two after firing (case head separation). The # of firings before it splits will be considerably less if you over bump the shoulders (by screwing down the die past where it should be).

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Sure. That's a good technique.

But the question is why is my JP chamber gauge giving me a false positive, i.e., indicating that tolerances are good enough when they aren't? A false negative is no big deal: if the gauge says "you may have a problem" but you don't and tolerances are actually OK, no real danger exists. You just check using your gun and drive on when it checks out.

But if you are using the JP gauge instead of an actual chamber to determine whether all your tolerances are still good, you are likely to just keep cranking the handle and be none the wiser until it's too late and (if you're using a Super 1050) you have a few buckets of defective brass. If the JP gauge tells you nothing is wrong, when something IS wrong, then you would be better of using NO gauge.

That is the issue. So, other than the possibility that I have a defective gauge, what sort of condition might explain the fact that a gauge whose entire purpose is to tell you "If your ammunition fits flush in this case gauge, it will go into battery AND EXTRACT WHEN NECESSARY" is giving me a "go" on ammo that is not extracting from a gun with a 5.56 NATO chamber?

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What make barrel is it with the chamber that is tighter than the JP?

Supposedly, the chamber checker is cut with a chamber cutter/reamer so it should be the exact same. I believe they use wylde as well.

You may just have a really tight chamber in one of the barrels.

Call JP. They have always been very helpful when I had questions.

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Here are pics of (1) a once-fired, un-sized case in the Dillon headspace/case gauge; (2) same case in the JP gauge; (3) a sized case in the JP gauge; (4) same case and gauge, different angle. post-17675-0-19776500-1375625304_thumb.jpost-17675-0-93489900-1375625330_thumb.jpost-17675-0-93489900-1375625330_thumb.jpost-17675-0-19776500-1375625304_thumb.j

post-17675-0-45912700-1375625349_thumb.j

post-17675-0-69774000-1375625404_thumb.j

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One is a Daniel Defense with a 5.56 NATO chamber. The other is a Blackhole Weaponry with a Wylde chamber. The 5.56 chamber should be a good deal more sloppy than the JP Wylde. I adjusted my dies and cranked out of plenty of ammo that functioned great--using the two guns as chamber checkers. Still baffled by the Riddle of the Gauge.

I'll definitely call JP.

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Is the head flush with the top step of the gauge or the bottom step? Or is it in between? For my rifle, if it was flush with the top step, brass was hard to eject. I had to dial the sizer die down just a little further to get the head in between the steps and then it was smooth as silk to extract the rounds.

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Most likely the shoulder/neck junction is not defined/sharp enough...

try marking a case with a black marker and see where the scratches are after chambering.

Just a guess from experience...

:)

jj

Still my best guess...shoulder/neck junction is not sharp enough...I solved this problem with a body die after sizing/decapping before trim. Others have solved it by screwing the sizing die down 1/4 - 1/2 turn PAST shell plate contact.

jj

Edited by RiggerJJ
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Trodrig, Rigger: these last two replies are interesting. First, I've definitely started doubting that I was reading my JP gauge correctly. But after reading Trodrig's reply, I went in and squinted at a few of the cases I prepped for a while under a good light in the gauge. The cases are definitely below the highest step--and very close to, if not actually, flush with the bottom step.

I love JP, but if I have to squint and ponder so closely, then I save no time over just loading up a bunch of randomly selected cartridges in a mag and working the charging handle every so often. And if the cases are sitting how they are supposed to sit, then it may be that having this gauge is worse than having NO gauge.

Rigger: your description of the shoulder/neck junction may be spot on. I'll try to capture what I'm seeing in some pictures tomorrow. What I'm seeing in the cases that function nicely after adjusting the die down (until "cam over") reminds me a bit of an Ackley-esque sort of junction: sharper, just like I think you're getting at. Does that sound right?

My boggle: why are the cases that stick in my chambers dropping into the gauge?? Is my die somehow slightly out of spec? Did I get a bad gauge? I guess I'll have to see what JP has to say.

In the meantime, adjusting the die down to the point where I get the "cam over" effect has done the job. I'm not seeing any flex in the shell plate, but I just can't help but wish that adjusting the die as Dillon instructs would work!!!

But, I see plenty of people on these forums using the cam over method.

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Trodrig, Rigger: these last two replies are interesting. First, I've definitely started doubting that I was reading my JP gauge correctly. But after reading Trodrig's reply, I went in and squinted at a few of the cases I prepped for a while under a good light in the gauge. The cases are definitely below the highest step--and very close to, if not actually, flush with the bottom step.

I love JP, but if I have to squint and ponder so closely, then I save no time over just loading up a bunch of randomly selected cartridges in a mag and working the charging handle every so often. And if the cases are sitting how they are supposed to sit, then it may be that having this gauge is worse than having NO gauge.

Rigger: your description of the shoulder/neck junction may be spot on. I'll try to capture what I'm seeing in some pictures tomorrow. What I'm seeing in the cases that function nicely after adjusting the die down (until "cam over") reminds me a bit of an Ackley-esque sort of junction: sharper, just like I think you're getting at. Does that sound right?

My boggle: why are the cases that stick in my chambers dropping into the gauge?? Is my die somehow slightly out of spec? Did I get a bad gauge? I guess I'll have to see what JP has to say.

In the meantime, adjusting the die down to the point where I get the "cam over" effect has done the job. I'm not seeing any flex in the shell plate, but I just can't help but wish that adjusting the die as Dillon instructs would work!!!

But, I see plenty of people on these forums using the cam over method.

Not sure what 1050 instructions say but my XL650 and the Dillon die instructions both say "Re adjust the die as nedded to achive proper headspace". It's pretty clear the back off 1/2 turn is just a starting point. I do feel that it's odd to adjust it to cam-over, but that's what's needed. Dillon instructed me to do it when I called them during set up of my press. As to your gauges, that doesn't seem right that they indicate good ammo when it's not. Prior to adjusting to cam-over my Dillon gauge was giving me a no-go reading. I'd call JP and see what they say.

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