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Discussion Starter #1
(Hope this is the right place to put this, the choices on the handloading section just didn't seem to match up.)

I had my Rossie to the range last week and fired quite a few rounds through it. But the last six were from a bunch of reloads I bought at the last gunshow.
(I checked them by pulling the bullets and checking the powder charges, to make sure of no excessive loads or double charges, but what I didn't take into consideration is under charges.)
The last six were some brand of 230gr JHP, and they were loaded so light the cases didn't expand to seal the chamber. This caused a lot of blowby and if it were not for my glasses I'd be in trouble now. They did make it out of the barrel, I counted the holes in the target as I shot the stuff.

My question is: How much pressure does it take to expand a straight walled case such as the .45 Colt to seal the chamber in a rifle?
 

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Going to all be guessing as home-brew pressure readings are pretty much like reading tea leaves...if there has been published data on the amount of pressure it takes to expand brass to a seal, I missed it.

Have to take into account the hardness of the brass, the number of times it's been cycled through loading (it does become harder...less ductile....at each firing, and the more the brass is worked by the die, the harder it becomes) and the diameter of the chamber in which it is fired (with larger being harder to seal than smaller).

HAve to take into account the burning speed of the powder...if gas gets between the case and the chember early, as pressure rises, the case still won't seal (once open...the system just won't close easy...some might fast .240WM loads still tend to collape the case shoulder and come out sooty).

ON a WAG, from lodaing a lot of mouse-poot loads, I'd think that something in the order of 11K-12K for .45Colt cases to form a non-leaking seal..with brand new cases perhaps taking 10% less. Find that most .22CB caps doen't seal all that well, but that case is thinner and the pressure level is pretty low. About 1/2 the factory .32SW (the short one,,,not the .32SWL) come out sooty.
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Know it's not what you asked, but when working with very lite-loadsm prefer to use fired cases that are only sized enough to enter the chamber. Sooty, non-sealing, cases are not just an aggrivation, with light loads it introduces a variable...some seal, some don't, so some lose pressure to the rear and others don't....that makes lite-load accurcy hard to come by.
 

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The Hog Whisperer (Administrator)
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It's not a simple answer because the cartridge doesn't achieve peak pressure instantly, so there will always be a little soot on the case.

It actually shouldn't be too hard to calculate, just need to know the elastic limit for 70/30 cartridge brass in a tensile load, and how thick it is, and crunch the numbers. I forget off the top of my head and am too tired to go look it up right this instant....

But yeah, those were loaded very light, or powder was way too slow and a lot of powder gas leaked out before the pressure peak, or a combination of the two.

Factory .45 Colt is around 14,000CUP, or even less, and generally they seal up OK.

I personally steer clear of 'garage brand' reloads myself....

Pretty good WAGs, Ribbonstone, I would say. You'd think 10K CUP would do it....
 

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Discussion Starter #4
I personally steer clear of 'garage brand' reloads myself....
Normally so do I. For some reason this batch of 35 rounds, was bought for the brass and just got shot. Usually I would have pulled the bullets dumped the powder and put in a known ammount of new powder.
But it brought up the question of just how much pressure does it take to expand the case to seal the chamber.

I suppose I could have thought all month and not asked a question with more variables.

As for the brass, they were W-W and looked to be once fired then loaded.
 

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Spend a lot of time loading mouse-poot loads for big rifles so I can shoot off hand at an indoor range in foul weather. Use some small centerfire rifle rounds as well for the same practice (.32-20 / 9mm Largo / 38-40) and some antique rifles (45-70 / 50-70). Just seems that if my graph of assumed pressure is right, things get "iffy" at 10K. If I have thin soft new brass, they form to the chamber and don't soot up the case or blow gass into my face at about this level. Old brass (that has grown harder) or brass that is made a bit thick at the start takes more...the 9mm Largo "Destroyer" Carbine is a good example. Takes at least 14K to get those cases to complete seal.

Some rounds, even with new brass, are really bad about this. Have a .401WSL I hunt with, but it takes at least 16-20K to seal those cases (they are THICK)...and no slow powders need apply.
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Good advice to steer clear of any relaod that you didn't pull the handle on. Better to spend the $ on either factory loads or new brass you reload yourself. Can still screw up, but at least you'll know who to blame.
 

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Discussion Starter #6
Good advice to steer clear of any relaod that you didn't pull the handle on.
Absolutly true, and I usually do this. Normally I don't even buy commercial reloads, let alone those of unknown herritage. But I guess this was a case of lazyness. I did check some of them and not all of them.
You are right, I should have pulled 'em all and then put a known powder charge in. But I didn't.
I won't do it again though.
 

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J Miller
I would venture to guess these "Reloads" were of the very mild Cowboy stuff? If they are there lies the problem!! The 45LC is a very large case and loading them with such small charges creates dangerous situations-stuck bullets etc!
Just about all the manuals have "WARNINGS" in them about this !! So what was the charge weight/Powder used ? If it was below 6 grs of just about anything out there your looking for trouble!!:rolleyes:
 

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Discussion Starter #8
Gunnut45/454,

I don't remember what charge was in it. I checked to be sure it wasn't an over charge, didn't think about an under charge.
I doubt they were cowboy loads, the bullets were jacketed.

Wierd thing to me is that I have loaded the .45 Colt for almost 30 years now.
Loaded mostly 250-270 grain bullets. Sometimes 200gr SWCs, and lately some 300grn bullets.

I've loaded, light, standard, and +P loads.
I've loaded black and smokeless powder.

I've done this in 4 different rifles and numerous revolvers and up till the six rounds that started this thread I have never had a case of such light pressure that it would blow unburned powder and crap back through the action of a rifle.

(OH, one exception. I loaded some Pyrodex that just didn't have the pressure to expand the case and it filled the action of my Win 94 Trapper with gook so fast that the gun was useless in about 20 rounds.)

I have learned my lesson. Next time I buy unknown reloads for the components, I'm pulling ALL of them down and then replacing the powder with a known charge.
 

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J Miller
Yep if it wasn't lite charge then maybe the primers we're weak or the powder was bad? Did they seem to fire correctly other then the blow back? What case?
 

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Discussion Starter #10
Gunnut45/454,

Cases: W-W, apeared once fired then reloaded.


Won't argue about the primers. Had 35 rounds. Fired 29 in my Ruger, all went bang nicely, but these 6 I chose to fire from the Rossie.

Bad powder, could be?

Last night when I was counting clicks and centering my rear sight I decided to see if there was any unburned powder left in the barrel. Yep there was.

I recovered it and it looked like very fine granuals. Couldn't tell what the original color was, but they were hard and gritty little granuals.
Actually they looked like flea dirt.

My suspicions are that this was a light load of a slow burning powder.
By the looks of that misc batch of ammo I'm thinking they were leftovers from test loads.
 
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