Well this is frustrating... .308 not fitting in case gauge.

I reloaded some test rounds of 308, and at the range one got stuck in the chamber, requiring me to take it back home to my bench to get it unstuck. I stopped with the test firing and bought a Sheridan case gauge, which I just got in the mail.

As I suspected, the case didn't fit in the case gauge. I then went and checked the rest of my rounds, and 20% of the finished test rounds wouldn't fit. So, I grabbed a few of the resized brass and tested them, and same thing; about 20% of them just won't fit in the case gauge.

My Lyman turret press had snapped the main turret bolt during resizing this lot, so I figured that probably had something to do with it. In the meantime, I upgraded to a Redding T7.

The first thing I did was resize a few pieces of the previously resized brass that didn't fit in the case gauge again in the new Redding press. They still didn't fit. I double checked die adjustments, resized again, and same thing. I then over-adjusted until it cammed over, but the resized brass still won't fit in the case gauge. The resized brass looks like any other piece of brass I've resized. Nothing looks off.





I flipped the case upside down just to make sure it wasn't the rim, and the rim will fit into the top of the case gauge, so that doesn't look likely.



The brass is all once fired, ordered online. I sorted it all by headstamp manufacturer (WMA), though I did not sort years. Most of the brass is '16-'20. There does not appear to be any correlation between year and not fitting in the case gauge. The brass was all trimmed to 2.005" after resizing, and was then chamfered and deburred and tumbled overnight.

Dies used are RCBS sizing and bullet seating and a Lee factory crimp die. The cases were lubed with One Shot. The cases all resized with a normal amount of effort.

I've never had any issues like this before, and I'm quite stumped at what is going on.

I can safely rule out any issues past the resizing stage, since the unloaded cases aren't fitting.

So what in the hell is going on here???

Thanks for the replies. The issue started when a round got stuck in the chamber. That's what caused me to look for a problem.

I don't have any 308 commercial ammo. However, that's a great idea to see how that fits in the case gauge and then compare measurements. I'll check with a friend who probably has some that I can use.

runner3264 said:

How much did you cam over? Sometimes you need to cam over more. The rim doesn't look right but it just can be the pic.
What lube are you using?

Click to expand...

I continued camming over until it was impractical and I couldn't even come close to bring it down a full stroke. No difference noted at any point.

I'm using Hornady One Shot for lube.

BBarn said:

Sounds like the lowest portion of the case body just above the rim groove is oversize. Perhaps you can measure that diameter and compare it to the SAAMI case dimensions.

if that's the issue, make sure the shellholder touches the bottom of the die at the top of the stroke when actually sizing a case. If that doesn't resolve the issue, you can also try removing the decapping pin and inserting a feeler gauge (of a few thousandths) between the shellholder and casehead when resizing.

Click to expand...

I measured, and it's within SAAMI specs. I stopped by my friend's house and picked up a steel cased Barnaul (all he had in 308), and it slid right into the case gauge no problem. The lowest portion of the case body of the Barnaul case was 0.002" smaller than my reloads (0.468" vs 0.470"), but both were within SAAMI specs. That was the only difference. All the measurements were within specs. I'm wondering if my calipers are off now too...

South Prairie Jim said:

Typical of brass fired in a different chamber than yours the radial dimensions at the .200 datum and most likely the case shoulder junction after firing are beyond the sizing capability of your fl sizing die.
It appears in your Sheridan gage picture confirms to tight at those datum’s .lowering the die won’t help much except base to datum length however a small base die usually will cure it.
Best way is to use new brass only fired in your chamber and monitor radial expansion before and after firing.

Click to expand...

It does sound like a new small base die is going to be my best bet...

armydog said:

Right after I size a case, I put it right in the case gauge. It's in my hand as I work the ram. If I catch one that isn't sized right, I will do a 1/4 more turn and if that don't work it goes in a bin to get run through the SB. If that doesn't work, it gets tossed. Very rarely will I get a case where nothing I do will help, but after realizing all the measurements are good to go, it will still remain a mystery. lol But I get it sorted out right as I take it out of the shell holder when I ram it to get sized. And the step right after I crimp, it goes back in the case gauge. A bit redundant, but I check all my cases for pistol and rifle once after sizing and once after crimping.

Click to expand...

I think what I'll do is to order a SB die and run all of the ones that are out of spec through it. Then once I fire them through my gun, I'll run them through the regular FL sizing die. If there are no issues, than it probably is just a case of one fired in a different chamber that my FL die can't size, as @South Prairie Jim said.

243winxb said:

Change to RCBS 2, use a pad to lube.

Click to expand...

I'm currently using RCBS 2 die set. I've used pads to lube, and I MUCH prefer One Shot. Just to be thorough though, I used my Lyman pad to lube, ran it through, and it made no difference.

Thanks again everyone for your help. I just ordered a Redding SB sizing die. I'll report back here once I get to use it. Amazon tells me it will be here Friday.

oldfortyfiveauto said:

FYI....I had some 7.62/308 that had been run through a machine gun. Had to take .020" off a shell holder to bring it back to spec. And that was after annealing.

Click to expand...

This is an interesting idea that I hadn't even considered... Shaving some off a shell holder. I don't have any machining tools with the ability to evenly remove a specific amount of material, but if I did, I'd give this a whirl. Thanks.

243winxb said:

At the top of the stroke when fl sizing, are shell holder and bottom of fl die in full contact? May need a flash light to see.

Click to expand...

Yes. It definitely is. Thanks!

Atavar said:

I am not a rifle expert by any means, but it looks like the major diameter of your shoulder is tight to the gauge at the same time the case head is standing proud. That would say to me you need to push the shoulder back a bit more somehow.
I am more asking to be educated than avering that I understand the problem.
Instead of shaving the shell holder is there enough slack to slip a feeler gauge under the case in the shell holder to shim it a bit closer to the die?

Click to expand...

Here's another picture of it in the case gauge. There is actually a bit of space between the case and gauge all around the shoulder. It doesn't show up well in the pictures though.



I'm not understanding what you mean by the feeler gauge. Wouldn't that increase the distance between the shell holder and the die? Maybe I'm misunderstanding.