9mm cartridge gauge

[noylj]

>I used the barrel as a gauge and with some of the rounds they would plunk fine but on others they would not even though it has the same oal.
>If you have rounds that will not pass the plunk test then I would say that on those rounds concentricity/coaxiality is out.

Different bullets impact the lede/rifling at different lengths. There is no single COL for all bullets.
IF this wasn't already posted, here you go again:
Per Ramshot:
"SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as
1) magazine length (space),
2) freebore-lead dimensions of the barrel,
3) ogive or profile of the projectile and
4) position of cannelure or crimp groove.
• Always begin loading at the minimum ‘Start Load.’"

Your COL (OAL) is determined by your barrel (chamber and throat dimensions) and your gun (feed ramp) and your magazine (COL that fits magazine and when the magazine lips release the round for feeding) and the PARTICULAR bullet you are using. What worked in a pressure barrel or the lab's gun or in my gun has very little to do with what will work best in your gun.
Take the barrel out of the gun. Create two inert dummy rounds (no powder or primer) at max COL and remove enough case mouth flare for rounds to chamber (you can achieve this by using a sized case—expand-and-flare it, and remove the flare just until the case "plunks" in the barrel).
Drop the inert rounds in and decrease the COL until they chamber completely. This will be your "max" effective COL. I prefer to have the case head flush with the barrel hood. After this, place the inert rounds in the magazine and be sure they fit the magazine and feed and chamber.
You can also do this for any chambering problems you have. Remove the barrel and drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop round in barrel (or gage) and rotate it back-and-forth.
Remove and inspect the round:
1) scratches on bullet--COL is too long
2) scratches on edge of the case mouth--insufficient crimp
3) scratches just below the case mouth--too much crimp, you're crushing the case
4) scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit
5) scratches on case just above extractor groove--case bulge not removed during sizing. May need a bulge buster.

[Louca]

To address your question, I use L.E. Wilson case gauges.

To address the discussion on whether it is worth it to use a case gauge or use a removed barrel with the plunk test, I would say I do both, but I think using the case gauge is a better thing to do. Using the case gauge tells me things about my reloading equipment and even my brass. I literally run every one of my thousands per year 9mm hand loads through the case gauge.

For example, recently the case gauge told me my final station (crimp) was not adjusted quite right. All the rounds I made would pass the plunk test in my barrel, so I knew they were probably OK to shoot, but the case gauge showed that I did not have enough crimp. Sometimes insufficient crimp can allow bullet setback, although I never experienced that. So I made a slight adjustment and now the case gauge loves them, and I am happier knowing the bullet is held a little tighter.

So for pistol rounds, I like using the gauge to let me know of something that might be going out of adjustment.

[shooter1911]

For example, recently the case gauge told me my final station (crimp) was not adjusted quite right.

OK, I give up. How did your guage tell you the crimp was not adequate?

[ShootistPRS]

Case gauges typically measure the length of the case and sometimes they will be a close enough fit to tell you that a case or neck is too fat. They will not tell you if your bullet is seated too long which is why I use the barrel removed from my gun to check loaded brass. Since I trim as a part of normal reloading I know that my cases are the right length for my gun and the brass is sized and crimped to the same point every time There is no need for a case gauge. I just have to make sure the seater seats the bullet deep enough for the case to chamber in my gun.

[rdtompki]

I use the barrels for OAL since I'm loading for several different 9mm guns, but a case gauge is handy as a rarely needed sanity not requiring I unload my carry gun.

[Louca]

OK, I give up. How did your guage tell you the crimp was not adequate?

Sorry for the late response, been busy. A few of my cartridges would not drop completely into the gauge, telling me the cartridge had a case that was either too long, or too large in diameter somewhere to prevent it from dropping all the way in. When I mic'd for length, they were good. When I adjusted the crimp die a little, they all started "passing".

Hope my explanation helps.

[sirgilligan]

For my 9mm I just got a Lymann Max Cartridge Gauge.

http://www.lymanproducts.com/lyman/c...-max-gauge.php

For my rifles I have L.E. Wilson.

The Lymann checkes the brass after resizing. It has a shelf (because 9mm Luger headspaces off of the case mouth rim) and you can check if the brass is within SAMMI spec for length. If the brass won't drop into the case guage then it may be too big around and needs further resizing. Then after you seat the bullet you drop it in and if you haven't taken the flair out (probably what the one post is saying about the crimp) it won't go in. If it goes in, set the gauge down on the table and if the loaded round is too long the cartridge will rise up in the gauge and the case head will be above the spec markings on the gauge.

Here is the instruction manual.

http://www.lymanproducts.com/lyman/c..._GA_Pistol.pdf

[Louca]

Since I trim as a part of normal reloading I know that my cases are the right length for my gun and the brass is sized and crimped to the same point every time

The original post was regarding 9mm cartridges. You actually trim your brass? I have never heard of anyone having to trim 9mm cases.

the brass is sized and crimped to the same point every time

Yeah, and the case gauge checks that, very precisely.

There is no need for a case gauge

It all comes down to accuracy. There is a need for one if you want an accurate check that your cases meet maximum SAAMI specs. If you don't require that, then the less accurate plunk test might be fine.

[PPGMD]

The most accurate way to check if a round will chamber is to use the barrel of the gun that you will be using that ammo in. It is also the most time consuming, and honestly annoying.

But perfect is the enemy of good. If I had to use my barrel as my case gauge I would probably gauge less than 1% of the ammo I produce. Unless you are doing load development to achieve best OAL for your barrel, I suggest using a quality multi-hole case gauge.

The two best on the market are the EGW case gauges, and the Shockbottle 100 round case gauge. The EGW gauges are available in a variety of sizes and configurations, and are made with chamber reamers that are at the very minimum chamber dimensions. If it drops in and out of an EGW gauge it will chamber in almost any gun.

The Shockbottle gauge is a little looser of a chamber, but still tighter than most chambers (even match chambers). It has a number of features that make it better than the EGW gauges. But the best feature is the fact that you can load the gauge up and flip it into a 100 round Dillon or MTM box. Because of this feature I case gauge every round. Something I would never do if I had to use my barrel, the EGW 7 hole 9mm gauge, or the 4 caliber EGW USPSA gauge (other gauges I own).