Case gauge?

Chamber and case gauges catch all types of quality issue. I have one for nearly all the cartridges I reload and check every round I reload if I can. They catch things before they go in your gun. A damaged case mouth, a burr on a rim, a split case, a high primer, or those rare cases where you ran a 357 Sig or 38 Super through your 40S&W progress press. The case gauge check process is a good QC practice that catches lots of anomalies. Everything I reload for competition get case gauged, even factory ammo on the very rare occasion I have use it in competition.

Must have item. Especially for bottle neck brass. Remember to use after the initial sizing step....check every case. This will save you time and hassle down the road.

.40

I like the Sheridan Engineering slot gauge which is cut out on most of the length on one side. I believe it is machined to minimum SAAMI chamber dimensions. The theory is if it checks OK, it should work in any gun. I also use the standard Wilson gauge. If the round does not easily drop into the Sheridan, I will normally use a dry erase marker to see where it is hanging up. Of course I also believe that removing the barrel in a semi-automatic pistol and dropping the round in to make sure it goes all the way in and is easy to turn is the best gauge of all.

To answer your question, a properly sized round should not need to be run through a gauge but as others have pointed out, not all sized rounds are properly sized.

I got one as soon as I had a 5.56/223. The lower part of the case does not enter the sizing die and it may be slightly blown out. You'd be surprised at the number of freshly sized 223 cases won't fully go into the gauge. The cases are too cheap to gamble with your AR not fully locking up or causing FTF's.

I use the EGW 7 hole gauges for pistol rounds.

The Sheridan slot gauge is a must for bottleneck rounds. Especially for trouble shooting.

I'm going to buy a EGW 7 hole gauge for 300 Blackout for testing rounds. I use my Sheridan to get everything setup.

For me case gauges caused more problems than they solved. When I first got a semi-auto pistol I figgered I needed a case gauge. I fought my press, dies, brass and bullets, adjusting and readjusting nearly every thing adjustable to get the rim of my 45 ACP handloads to sit right according to the step on the gauge. I then read about the plunk test, put the gauge in a drawer somewhere and happily/successfully loaded several thousand rounds since. I got a Garand and researched reloading for a 30-06 semi auto and again thought I may need a case gauge (I guess I forgot my previous experiences with a case gauge). I started with light reloads using HXP brass, and the reloads "seemed" to fit the gauge. Then I started getting rounds that would leave about .010" of the case head standing tall. Again I fought dies and adjustments and even bought new dies and premium bullets. Frustrated I asked about my problem on the CMP forum (lots of Garand guys there). One member replied "do they chamber OK?, if so just shoot them". I disassembled the action and Lo and Behold, yep the rounds fell into the chamber and dropped out freely. I put the gauge in a drawer somewhere and have reloaded quite a few rounds happily and quite successfully. Later I discovered that with a bit higher load the brass was hitting the OP rod hump on it's way out of the gun. The rims were getting dinged and the rounds would not gauge properly. The plunk test had worked quite well with my 3, 45 ACPs, and my 3, 9mm pistols and I F/L size my Garand brass. I have never had a chambering problem with any of my 8 semi-auto pistol reloads, just using the plunk test. Jes my experience...

M-14 said:

How important is it to have/use case gauges? If I do a full re-size why would you need to check it? Just curious...

Click to expand...

For rifle shooting, particularly for the Garand and M1a, if your case is not smaller than the chamber, then the risk of an out of battery slamfire is high. And that is no joke.

This is an M1 carbine, functionally similar to Garands and M1a's, and they also slamfire out of battery.


These actions have free floating firing pins, and if the bolt has to de accelerate to crunch fit an overly long case to the chamber, these guns will slamfire right at cam down




Like this.



Once you buy rifle cartridge headspace gauges, you will find the advice that comes with sizing dies, that is to the shell holder and add a quarter turn, is worthless. Seldom if ever will that size a case between Go and No Go



I like this gage, I use it all the time, have one on my reloading bench when I am sizing 308 and 30-06 cases, because, believe or not, each batch of brass may require a slight adjustment of the die to size the cases between Go and No Go




I have not bothered with case gauges for pistol calibers. But rifle, I own many.

I have a Wilson gauge for every caliber I load.

Every reloader should have one for each caliber they reload.... I do, and use them often.

No need for me. I do use one for my 5.7 as it is picky but 223 to 06 and other pistol rounds it is not needed. Full length size rifle and plunk pistol and im good.

I've found rounds with bulges my eyes could not see with a case gauge and or plunk testing. Some of them were so bad they would have certainly jammed the gun if I tried to use them. Pretty sure the bulged when seating/crimping at the end of the process - so, sizing the case wasn't good enough, the error took place after the cases were fully sized to spec.

Texas10mm said:

The Sheridan slot gauge is a must for bottleneck rounds.

Click to expand...

What is the practical benefit of the slotted gauge? My eyes are good but not better than a gauge. It seems if there's an imperfection (x thou, not discernible to the eye) on the part of the case exposed to the slot, that the imperfection would not be detected by the gauge and could go unnoticed until chambering. Thus, one would have to turn the round in the gauge to ensure in-spec symmetry. What is that the eye can detect that the gauge cannot?

I have L E Wilson adjustable case gauges for bottle neck rifle cartridges. The benefit of being adjustable is that you are gauging headspace relative to your specific chamber vs. SAAMI max specs.

But back to the original question, yeah, I have gauges for my cartridges, L E Wilsons. I'd rather replace a relatively inexpensive gauge than fumble a barrel onto the cement floor - lots of handling and movement during reloading/gauging.

Herman B said:

What is the practical benefit of the slotted gauge?

Click to expand...

It is cool for one thing. Sheridan will sell you a non slotted gage for not quite half the price of the slotted. But I wanted the slotted, and it makes me feel better.

I make custom ammo for my particular guns.

Never have seen the need for a generic chamber gauge. All my guns have built in chamber gauges. The chamber of the gun.

For my semi auto pistols I'm quite fond of the shock bottle gauges that let me do a hundred at a time, they also make it easy to box them up, for 223 I also use a guage that does 100 at a time. The other calibers I use a wilson or Sheridan, they all work. In 2019 I shot over 17k rounds of 9mm and 40 S&W, easily another 5k in 45acp and 5k of 223, not a chance in hell I'm gonna sit and plunk every one in the barrel of my gun, may be fine for the guy loading a few boxes a year though. So to me they're definitely important.

I have loaded about 7k of 45 and 9mm and have experienced 3 cases that have not gone fully into battery. I dont use a guage for pistol but I also dont shoot completion. I own several for rifle and they are all wilson. I normally test all of those due to the much lower volume, and I have shot several rifle matches.

Gauge or plunk, don't leave home without one.

M-14 said:

I am getting set-up to reload again after a long time away, (if they ever ship the stuff). I'm getting things I did not have before. I understand about slam fires and free floating firing pins as 98% of my inventory is that way. So that is why I asked as the finer points need refreshing in my mind. I'm only going to do 7.62x51 at first using NATO brass. Diamond K washed cases arrived today, which reminded me I need a swager, so I think I will add a gauge to my order also.

Click to expand...

If you are reloading for a Garand or M1a, use the least sensitive primer you can. I recommend the CCI #34's because CCI says these are their military product line, which means a less sensitive primer than the commercial product line. Do not use Federals as they the most slamfiring primer on the market. When I had my slamfires, with Federals, I asked around and the one common theme to those competitive shooters who had had out of battery slamfires, was Federal primers. Federal primers are great in bolt guns but they are too sensitive for the Garand mechanism.

The thing is, the Garand/M14/M1 carbine/Mini 14 mechanism has, and will slamfire out of battery with military and factory ammunition. Every so often an extra sensitive primer comes out of the batch and in feeding, the free floating firing pin rebounds off the primer, and it ignites.





Since you cannot visually inspect primer sensitivity, the only real primer control you have is buying primers which are on, the average, less sensitive. That reduces the chances of having an extra sensitive primer in a round and reduces the risk of a slamfire to an acceptable level. But it is always there.

Always wear your shooting glasses!!

Sizing the case to less than chamber length and width, that is making the case smaller than the chamber, reduces the chances of an out of battery slamfire, because the bolt will not have to crunch fit the case to the chamber. As I said before, when the bolt has to stop to crunch fit a case, that firing pin rebounds off the primer, and that may cause the primer to ignite. If you are using once fired military brass you are better off using the Sheridan gages and a small base die. Standard sizing dies will not reduce big swollen cases enough to drop in a Sheridan case gauge. Sometimes, small base dies are not enough to reduce a big swollen case to drop in a Sheridan case gage. That is when you need a Roll Sizer.

Rollsizer.com

Case pro

Take your pick, almost $1000 apiece. But this level of mechanical and hydraulic compression is what is needed if a small base die cannot reduce once fired brass to fit in the chamber without resistance. Be aware, the very act of seating a bullet bulges a case a tiny bit. It shows up in the gauge.

If your brass is still too large after sizing in a small base die, it is better to take that stuff and use it in a bolt gun, and go buy new, never been fired, brass, and use that in your Garand/M1a/M1 Carbine/Mini 14.

Always wear your shooting glasses and always load from the magazine. The mere act of of loading from the magazine slows the bolt down a bit. Controlling slamfires in mechanisms with free floating firing pins is all about primer sensitivity and the kinetic energy of the firing pin.

I even sent a Garand bolt off to Roland Beaver and he drilled and installed a firing pin spring.

My case gage has caught some tiny cracks I had missed visually. Valuable tool.
I gage my rounds. Anything the gage catches is segregated and dealt with appropriately.

I gauge every round I might shoot in a match. This also allows me to catch high primers, sideways primers, and upside down primers. All three are very rare but can bring your shooting to a halt.

Anything that doesn't pass the gauge goes in the practice box.

I didn’t at first... And then came the FTC at the most inopportune time.
For pistol competition I use the Hondo/Shockbottle gauges and for 9mm it also helps to spot a .380 that made it’s way through the progressive. I know I know everyone says that shouldn’t happen but it does, so there.
Rifle cartridges have individual gauges. You can use your chamber like others have said but I prefer to add the QC step at the reloading bench.