poor-man case gage check: the barrel?

[Clint007]

Fellow that gave me instruction on the Dillon 550b suggested that the best way to ensure the round was not too long is to 'plonk' it into the (removed) barrel of my pistol.  I didn't have a case gauge (whatever that is) but I do have a good caliper.

I have read that CZs tend to have a shorter chamber than other brands. And accordingly, a longer 9mm round that works in one gun may not be well received in a CZ. Don't know if this is true, but I'm trying to make sure I understand the....mechanics...of this as I hand-load.

I deliberately made a few very long rounds (no powder or primer), and then dropped them into the barrel. There was no happy 'plonk' sound that my teacher insisted I learn to recognize, and moreover the round sticks in the barrel. When I lightly shake the barrel (with round sitting in it) up and down, the round does not 'bounce' up and down relative to the barrel. It sticks pretty well to the barrel.  In contrast, with shorter rounds (and factory ammo), the round is clearly 'loose' in the barrel and free to move up and down with shaking.

1) Is this because, when it's too long, the face of the bullet is jamming up against the rifling of the barrel, and getting caught up? In other words, the round is not headspacing on the case mouth like it should,  but is (wrongly) headspacing somewhere on the (too shallowly seated) bullet and digging in and thus sticking.
2) is this barrel test method a safe and reliable thing to use to confirm my rounds are not too long? In addition to loading manuals that dictate 'max' length of a 9mm round?
3) what would be the result if one fired a round that was too long , as my deliberately too-long round I mention above?
4) what are the merits/detractors of short versus longer rounds (but within acceptable limits)? I've read here that longer rounds can be more accurate.....why?  Shorter rounds generate more pressure = more velocity (is this right?) but if too short may not feed from the magazine (and why is this?)?


Thanks in advance to the gurus that answer!

Clint

[bang bang]

1) Is this because, when it's too long, the face of the bullet is jamming up against the rifling of the barrel, and getting caught up?

yes.

In other words, the round is not headspacing on the case mouth like it should,  but is (wrongly) headspacing somewhere on the (too shallowly seated) bullet and digging in and thus sticking.

yes.

2) is this barrel test method a safe and reliable thing to use to confirm my rounds are not too long? In addition to loading manuals that dictate 'max' length of a 9mm round?

yes and no.  you have the magazine too and the LOA maybe an issue there.  then theres the proof in the pudding test.  load up a mag and see how your gun like it.

The book is a guide and if you read it, it says so.  They use different setups/guns/test platforms and say so.  readup on what can cause problems in the reloads and how LOA can affect the load. 

the plunk test can tell you if the LOA is okay, but not too short.  Its just telling you it chambers FOR THAT PARTICULAR GUN AND THAT PARTICULAR BULLET.

the plunk test WONT tell you if you have the LOA too short or if youre compressing the powder. 

the LOA can be adjusted to your particular gun and should be verified/checked against the book, and whats going on in the case.  again, dont forget you have the mag too.

3) what would be the result if one fired a round that was too long , as my deliberately too-long round I mention above?

it may or may not fire depending on if the slide was in battery.  since your round is too long, many times the slide wont go into battery and will be out just far enough that either the hammer wont fall or if it does, wont touch the primer.   Ive never tried to do such things and i use common since when shooting.  IF i have issuse, i stop and examine things.   again, read your loading manaual since it give info on how they have tested this.   best case is that it will go bang.  worse case that it will blow off the case head and blow the mag out and maybe the grips. 

4) what are the merits/detractors of short versus longer rounds (but within acceptable limits)? I've read here that longer rounds can be more accurate.....why?  Shorter rounds generate more pressure = more velocity (is this right?) but if too short may not feed from the magazine (and why is this?)?

not sure about the accuracry issues with the LOA.

afa the mag issues, take a dummy round with proper LOA and see how it feeds from the mag up into the chamber and then take one thats really short and see what happens. 

if you wait, someone will chime in with alot of good graphics on your questions.

[Wobbly]

Clint -
Welcome aboard !

Your pal is right, the barrel is the ultimate judge of whether your reloads are the right shape and size. It is vastly better than a simple caliper, because so many of these issues depend on the case being round, and a caliper simply can't measure "roundness".

Your reloads may not be entering the chamber all the way due to 2 common issues...
? Improper crimp diameter (too large)
? Bullet striking the rifling (OAL too long for that particular bullet shape)

Crimp is the easiest dimension to mess up and should be checked first. Because the 9x19 is a tapered cartridge, crimp is far more important than say a 45ACP. If a round begins to enter a 45 chamber, then it can go all the way to "home" because it is nearly a straight wall. But the taper shape changes all the rules on 9mm Luger. It's all in the geometry of the problem. Stick a caliper on your reloaded case mouths and tell us what dimension you get.

The chamber on a CZ is (generally speaking) the same size as any other pistol. What's not the same is the freebore just in front of the chamber. This makes selection of the bullets you use critical. That is, while you could use any bullet in a Glock, you'll want to be very selective in picking bullets for your CZ. This cartoon explains why...



So some information on the case mouth dimension, the brand, weight and type of bullet you're using, along with the OAL would be very important in allowing us to proceed further.

Hope this helps! 

[noylj]

The barrel is your BEST case gage.
In general, you want the longest COL (CARTRIDGE overall length) that fits your magazine and reliably feeds and chambers in your gun. This is something that no one can tell you, as it all depends on your barrel's chamber and free-bore.
Any COL referenced in a manual is a minimum that the reloader should NOT load shorter.
Review your manuals for determination of COL.
I load a couple of inert dummy rounds (no primer or powder) to determine the COL for my gun(s).

[Clint007]

THanks for the replies, I appreciate it.
I will try to figure out how to load some images of my ongoing test of power factor and accuracy for my CZ 75 Shadow.

I concluded from some chronograph data that for a 124 gr Berry bullet, I needed about 3.7 gr of Titegroup to make the power factor reliably for IDPA. 3.8 gr was more than needed, and 3.6 gr was often inadequate. I haven't chrono'd the 3.7 loads, but tonight I did test just a few variations of COL at the range using 3.7 gr of TG.

In fact the shorter COL seemed slightly more accurate. All shots at 30 ft, using Titegroup (T.G.) powder, new unfired Winchester brass, with Berry's bullets. HBRN is hollow base round nose, the other is a flat point DS Berry's bullet.

I can't seem to see how to attach images to these posts....little help? I'm on a Mac...

This link may work

http://gallery.me.com/tannehill#100018

[Mr. Sasquatch]

Clint, that's some fine shooting and fine ammo!

P.S.
Note to self: Remember, never try to break into Clint's house.

[Clint007]

Thanks!  but I should add that all shots were sitting on a bench with sandbags under my hand whilst listening to accuracy-enhancing Zen music....

Clint

[Wobbly]

? Nice shooting!

? As to photo posting, upload the photo to a service (which you seem to have accomplished), bring up the photo, right click on the photo to "Copy Image Location", then use the far left icon with the Mona Lisa to paste in the web address.....



Like so !!


? So the question remains, did you ever start getting a "ting !" when you drop a round into your naked barrel?

Inquiring minds want to know. 

[Clint007]

Well, it's more of a "Plohnk" sound, lower pitched with a deeper resonance than a "ting", unless I drop in a round longer than 1.170" which is indeed more of a ting sound I guess. More easily validated is the 'shake' test I think as I described above, to identify too long a round...at least for me....

THx for help in posting pics...

Clint

[Wobbly]

Clint -

I surely wouldn't trust my safety to different people's interpretation of sound !! That may work pretty well if you want to know if the local symphony orchestra played the Mozart piece well enough to keep the reviewer from puking into his hat.    But here we are talking about the safety of fingers and eye balls. In other words, this ain't hand grenades and "close" really isn't good enough.

You should want to know within .001" where you are.

One method I have used to achieve this is discussed here.... IN THIS THREAD


Hope this helps! 

[Clint007]

I use a caliper to measure, of course, and I don't exceed specs, but I thought u were asking bout my particular sounds with the naked barrel test.
My point was, a plonk vs a ting vs a thunk is subjective. the barrel shake - the round 'sticking' to the rifling, is less so. Agreed, the length is the most objective,,,

Clint

[Wobbly]

Clint -
Not to argue or beat on a dead subject, but rather to make sure we're on the same page. In my book, your safety demands this. So please bare with me while I seek clarification.....

I use a caliper to measure, of course, and I don't exceed specs.....

Of course you do, and that's commendable, but the point is there is no way to derive a safe OAL with only a caliper.

....but I thought u were asking bout my particular sounds with the naked barrel test. My point was, a plonk vs a ting vs a thunk is subjective. the barrel shake - the round 'sticking' to the rifling, is less so. Agreed, the length is the most objective.

"Subjective" is the precise word. Even if we both reported the exact same sound, my ears are not your ears. Furthermore, consider that our cartridges might make that same sound and yours be .002" off the rifling whereas mine might be .013" off the rifling. So it pays to know exactly what's going on in places you can't visually check.

For example: Suppose your press produced finished ammo that varied in length by + or - .004". Normally we would say that is GREAT ammo! But we would not say that if we know your bullet was only .002" from the rifling because any ammo that was +.003" or +.004" would be dangerous because it's already into the rifling, and thereby raising he chamber pressure.

Follow? So I just want you to be sure of what you have so you can allow some room for error. 


And therein lies my sole concern. 

[Clint007]

Ok, I see what you mean, and how important that point is.

When I made my deliberately too long rounds, I did them in .005 increments. I did three of each and found the rifling contact only occured (with this particular bullet) when the measured oal was 1.175.
Given that my round length variation did not exceed .008 at the worst extreme, setting 1.165 as the absolut max seemed reasonable.

But, in point of fact, my accuracy suffers more with greater oal, so I will run a batch at 3.7 gr of Titegroup at shorter lengths and test those with a chrono and for accuracy, and dummy loads for magazine function.  Looking at what I've done so far, I think mysweet spot for IDPA ammo will be around 1.125 with 3.6-3.7 of TG for a 124gr HBRN Berry bullet. 

Question: What's best way to recognize or ensure you don't compress powder? I moved to Titegroup from Unique for that reason as I started shortening and going up in bullet weight (length)...

Thx

[armoredman]

I have used the barrel as a case gauge, and this is how. First, load a dummy with the possibly over long COAL, ( I only do this with that objective), and drop into the dismounted barrel. I am listening for a metallic "tink", not a leaden thud. Also, I check the slug for rifling marks. If the slug is over long, I progressively shorten it via press until it hits with that higher metallic sound. I have no case gauge, so this is the only one I can use. It is all very subjective, but one I use successfully, and I make sure to stay withing the recipe's guidelines on COAL.

So please bare with me

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[Wobbly]

So please bare with me

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