Overall cartridge length

Howard Law

bigdogdaddy

Tracker
Sep 16, 2012
827
0
0
Indiana
Thanks for the link Denny. As for the trim you mention millsriver, I am assuming that you are referring to trimming the length of the brass case. Not sure if it is because of the low pressure of a .45 acp round or something else, but my .45 brass never has needed trimmed. In fact, some measures a hair under the specific length measurement.
 

bigdogdaddy

Tracker
Sep 16, 2012
827
0
0
Indiana
BTW Denny, the link reminded me of a lucky deal I just ran into. I own a business where I sell & install invisible type fencing for dogs. I sell a lot of batteries for my collars, probably close to 1000 every year. Well just recently my battery source started sending my batteries in these nice little blue plastic boxes with a snap lid. Upon closer inspection I realized they are actually ammo boxes. Imagine how happy I was when I looked at the writing and it said 10mm or .45 acp! So I will not be using my recycled cardboard ammo boxes much longer. ;D
 
D

Denny4kids

Guest
Bigdog that’s a good score on the box's. I got my 10mm/45 box's the hard way, I thought they were 9mm when I bought them. It's all good.
I'm pretty new to reloading and I have never had to trim a pistol case. The reason that I run each cartridge through a gauge is to check for a deformed case like a bulge or a rolled over neck where the bullet is seated and of course the case length.
I had a Winchester white box round fail to chamber in a match one time and it took two racks of the slide and two wasted rounds to clear. After we scored my stage, a bud came to me a said good save! At first I wasn't sure what he meant and then realized I cleared a jam without thinking or taking my eyes off the targets. Besides being fun, this competition stuff is training me very well. Denny
 

Herk

Tracker
Mar 16, 2017
522
1,969
93
Colorado
Zip code
80537
I thought it would be better to bump an old thread than to create a new one on a topic that's already been covered:

Yesterday I went to the range before work and tested some handloads. I'd made up six different loads. The difference between them was powder charge and overall length of the cartridge (COAL). I did a "plunk test" to determine my max COAL:


Going by the advice in this guy's vid, my max COAL was 1.14", which I loaded three of the loads to. After looking at them, I thought they just didn't look right: the bullet's wax groove was sticking way out the end of the case and that didn't seem right so I made the three loads again but with a COAL of 1.06", which placed the wax ring just inside the case mouth.

The longer COAL rounds were a) unreliable (had to smack the slide shut after almost every round), b) inaccurate (all loads printed high, some rounds going over the top of the paper), and c) inconsistent (groups ranged from 4-7", not counting the rounds that went over top of the paper, which I can't measure, of course).

By contrast, the shorter rounds were a) 100% reliable, b) shooting to POA, and c) giving me groups of about 2.5".
:eekthumb:
The recoil of the shorter rounds was quite nice and there were no obvious signs of high pressure.

Is that Plunk Test a bunch of voodoo? After doing it I learned how long of a cartridge I could load, but the stuff I made up was worse in every way than the ammo whose COAL I came up with by seating the bullet deeper and deeper until I thought to myself "Yep, that looks about right." There's lots of info online about rifle COAL but not so much for pistol. Is there any scientific reason to pick a COAL/seating depth with pistol rounds or is what I did (i.e.: throw spaghetti at the wall and see if it sticks) as good a method as any? I could see being more cautious if you were using a max powder charge, but I wasn't even close.
 

dial1911

Mouse hunter
Site Supporter
Jul 15, 2015
17,544
32,769
113
Central Hades
Zip code
31210
I didn't watch the video.

But you've got to be careful with smokeless powder. It has a funny characteristic in that the higher the pressure, the faster it burns.

So reduced volume inside the case, i.e. deeper seating depth, can cause powder to be consumed faster and create even higher pressures (like over the top pressure).

A reloading recipe for a specific bullet should list the COAL for the loaded round. That is about as important as how much powder you put in the case.
 
  • Like
Reactions: Herk

dial1911

Mouse hunter
Site Supporter
Jul 15, 2015
17,544
32,769
113
Central Hades
Zip code
31210
Fucking youtube experts.... he kind of touched on it when he says "more space makes a shower round"... well, he should have said with emphasis that you don't load then short with out the opposite effect. And i would have said very clearly that if you're going to load shorter than the recipe, start low on the powder charge and work your way up.

Someone loading hot rounds that followed his advice might not be happy. These are pistol rounds, so they are generally fairly low pressure. Well, at least not the same as a rifle round.
 
  • Like
Reactions: Herk

Herk

Tracker
Mar 16, 2017
522
1,969
93
Colorado
Zip code
80537
Is there a way to measure pressure? I know you can measure velocity with a chronograph but I assume that doesn't necessarily tell you anything about pressure. I've also seen flattened primers as a sign of high pressure; is that a good indicator? Isn't loading too long also potentially a pressure issue? If the bullet starts out pressed against the rifling then there's more resistance to get moving and so pressure spikes, right?
 
  • Like
Reactions: dial1911

dial1911

Mouse hunter
Site Supporter
Jul 15, 2015
17,544
32,769
113
Central Hades
Zip code
31210
Is there a way to measure pressure? I know you can measure velocity with a chronograph but I assume that doesn't necessarily tell you anything about pressure. I've also seen flattened primers as a sign of high pressure; is that a good indicator? Isn't loading too long also potentially a pressure issue? If the bullet starts out pressed against the rifling then there's more resistance to get moving and so pressure spikes, right?

Yes, too long can be a problem too. Although i have not tested this, I'm not sure you could get rounds that long into a standard mag. I've seen long rounds be a problem in bolt actions though.

Cratered primers, flattened primers, blown out primers, shiny spots in the back of the brass (almost exclusive to rotary actions), split brass, bulged brass at the base, etc. are all high pressure signs.

Edit- can't test pressure without a special rig. Chrono speed is a very good indicator that you are in the good pressure range.
 
  • Like
Reactions: Herk

Herk

Tracker
Mar 16, 2017
522
1,969
93
Colorado
Zip code
80537
I think a friend of mine has a chrono but he's in the process of moving so it's probably packed up right now. Once he's completed the move I'll bug him to let me use it. In the mean time, I'm happy to say that my brass looks fine; none of the signs that you listed.

Another thing I thought of: what about recoil impulse? I've loaded some +P/max loads before and the muzzle flip was A LOT more than what I'm used to. These current loads are about what I'm used to from factory ammo, so is that an indicator that the pressure is *probably* fine? Not measurable or objective, I know, but it's something...