Cases fits gage but won’t chamber

[BlackdogGS]

I was loading 1,000 rounds of 5.56. I test fired after about 200, everything ops checked good. Started loading again and after a 100 or so I noticed my sizing die was loose. I reset it and continued. I test fired again and found they wouldn't chamber. Now I have about 200 rounds that gage good but half won't chamber. I'm trying to avoid pulling all of them apart as I know at least half are good. What could cause this?

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[Member 34319]

Clean your chamber?

 

[BlackdogGS]

Clean your chamber?

Yep. I tried 2 different rifles also.

 

[Member 34319]

Does your case gauge measure for bullet depth or just for the cases dims?

You mentioned your die came undone for a bit, chances are those rounds weren't seated to your correct depth.

Have a set of calibers to measure OAL?

 

[amusicman2]

That's why I tighten dies just past hand tight with my wrench. Fl sizing I'm assuming. And digital calipers are a must have. Hopefully all your cases are the same length. Very curious what you find out even though I've never ran into this problem myself.

 

[DizzyJ]

Hopefully you can salvage them

 

[Gonzales]

What case gauge are you using? Can you post a picture of a round in the gauge?

 

[BlackdogGS]

Since I had a bucket of rounds, some good some bad I had to find a way to sort them. Since I was losing trust in my Dillon gage I ended up using a spare LaRue barrel I had. When I dropped the rounds in, some stuck and some chambered. I was able to separate them that way. Remember they all fit in the gage well.

I think I know what happened. When my sizing die became loose I adjusted it by raising the platform and screwing the die I until it touched. Had I stopped there I would have beengood. But... when I gage checked it I found that the base was too high in the gage so I adjusted the die down until it sat flush like it's suppose to. By doing this it pushed the shoulder down and expended the base causing the rounds to stick. I guess I need a better gage.

 

[jordanka16]

I dont even own a gage, I use a barrel for pistol ammo and I measure with a comparator for rifle rounds.

 

[Johnny Tremain]

How about checking the case OAL if the neck is stretched, and the chamber dirty....

 

[P7M13]

Sizing die loosened. With as little as 25° of loosening, a die will be off by 5 mils.
If your cases are at the upper end of stretch, not sizing them enough would give a case neck too long, body too long, or with too much bulge at the base.
The neck or body length won't let a full bolt closure happen, the bulge would get stuck in the chamber. I suspect it's the body length on most, neck on a few, because a bulged base won't fit in the case gauge.
Case check gauges are tricky. I've had brass plunk in nicely but recognized that the neck stuck out too much or the base wasn't at surface or below. 4 mils is all it takes to make a no-go.
I've also had some NATO brass refuse to be sized down to fit the gauge. After 2-3 tries, I toss 'em.

I have resized some loaded 308 because I have neck bushing dies. Better just to pull, resize and reload.

 

[DizzyJ]

I dont even own a gage, I use a barrel for pistol ammo and I measure with a comparator for rifle rounds.

Ditto. I use the chamber as a gauge.

 

[Gonzales]

I know that they are expensive, but these are one of the best gauges. The slotted versions allow you to see what's wrong. They are also cut with a chamber reamer.

Sheridan Engineering - Slotted Ammunition Gauges