I have found a practical use for my .223 case gauge.
I no longer case gauge every piece of brass. If it was fired from my gun, already, I only do spot checks, unless I run into problems with a batch. Heck, my
unsized brass passes the case gauge nearly all of the time.
What I
always gauge are any
new range pickups,
before sizing. If they're significantly long, I trash them. I don't even try to size back down, because they're now weakened. And I can't do the paper clip test. Experience has shown that I can't feel at least 6 out of 7 incipient separations in a .223 case with the paper clip test, and there's nothing to say that the one in seven that I threw out would have even separated.
But with your rifle, I somehow highly doubt you're finding range pickups on a regular basis. The one thing you might like to try is put one of your FIRED cases into the gauge to do a before and after. This is a roundabout way to check your rifle's headspace, if you don't have the proper gauges. If you have excessive headspace, then you ought to be adjusting your die so you're not oversizing. A case gauge is useful because it sorta indirectly measures your headspace on a fired case, and it measured your die/setting on a sized case.
But with a bolt action, there's a cheaper way. You can back your die off little by little until your cases just barely chamber. That way you can find the spot where you're bumping the shoulders back just enough. If your headspace is tight, you can basically FLR all the way without any problem. Anyway, you'll find out soon enough. If you experience a separation in brass that has been fired only out of your rifle, then you will know your headspace is excessive and/or your die oversizes.
my No.1 has a pretty tight chamber, being that fired cases will drop free and drop right back in with no force, they also don't seem to be stretching most of the time
That doesn't tell you anything about your chamber. It just shows your load isn't overpressure. If you fire a moderate pressure load in a rifle, it will always easily chamber in the same rifle for at least a couple loadings, no matter how big the chamber is. This is the whole idea behind neck sizing. The only way to measure your headspace is by comparing the before and after cases in a gauge (or expert use of calipers), or by using a headspace gauge. Or you could be relatively confident your headspace is tight by noticing that some of your own modestly used brass is still snug on the bolt even after FLR.
Also, as others have noted, a separation isn't necessarily dangerous. My initial batch of 223 cases had a lot of bad apples (most of which I could have gotten rid of if I used the case gauge on them before sizing). I got to the point where if I experienced a stoppage, I'd automatically clear the head and jack another round in/out to extract the case, and keep shooting without missing a beat. I never felt so much as a puff of smoke on my cheek, and that's out of a bullpup.
