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Subsonic .308 load with 200 gr. bullet

Making a general statement like;

"...most if not all ammunition manufacturers have tried and failed to replicate it in the lab."

Well, just because it happens to be on hand, the Lee reloading manual states :
These conditions must all be present:
1) Very slow burning powders
2) Charge must be 25-35% under normal
3) Something special must happen about which no-one knows the details for certain
Conjecture includes...
then goes on:
Laborotories have been unsuccessful in replicating the event
... mention of the phenomenon is to encourage you to avoid reduced charges of very slow powders

Sorry, he doesn't annotate it so I can't point right now to his Laboratory tests.
Perhaps you know more than Mr Lee? Or have first hand experience to contribute to the common understanding?

I'll also just re-post this:
As always, your safety is in your own hands and everyone has to determine what they're comfortable doing.
 
This is why these kinds of discussions never get anywhere. If WHAT even happens? Did you mean that nobody can prove that Smokeless powder detonates or that smokeless powder in a cartridge case detonates? If people would bother to read even one of the references that I posted you'd see that the tests that were used to determine the velocity of detonation was done by filling a tube with powder and then detonating it - kind of like a cartridge case - a tube with powder in it. Common sense should tell you that if smokeless powder can detonate and that it can be detonated reliably in a closed cylinder then it might be possible to detonate smokeless powder in a cartridge case.

Inexact comments and generalities simply create rumors that some people misinterpret as fact and then we end up with people spreading Internet crap as truth.
"Kind of like", but not a cartridge case , eh.
It's that kind of unscientific extrapolation that generates inexact comments and creates rumors that some people misinterpret as fact and then we end up with people spreading Internet crap as truth.
A "closed cylinder" if different from one "with a plug in the end" which is "kind of more like" a cartridge case...

For a start no-one is sure detonation is the cause, but lets carry on and pretend it's relevant.

There is something of a difference between a booster charge of RDX (or whatever they used in your reference, I didn't bother to read it.) which could generate your 3-some-thousand m/s detonation wave. BUT rifle primers are made to DEFLAGRATE the powder and so are quite tightly engineered to be BELOW the speed of sound under any forseeable environmental conditions, some THREE TIMES LESS than your quoted detonation velocity.

You should possibly stick to this:
We can't find tests proving this phenomena either way because there haven't been any.

Here's some more internet conjecture: http://reloadammo.com/liteload.htm
 
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Well, I just got home from the salt mines, and thought I'd contribute information from a source that we should have probably checked to begin with. This is the old "1970" Lyman Reloading Handbook, and with every cartridge listed, they have a section covering cast bullet loads. Most powders listed are fast burning shotgun/pistol powders.

I trust this book and these loads. I've never done these 308 loads, but have done similar velocity and pressure loads in smaller bottle neck cartridges. Primers listed for these cast bullet loads were Winchester, (8 1/2-120), which I've never heard of.
IMG_2513.jpg


The guys over on the Cast Bullet Forum would prolly have a ton of info, specifically for the situation that the OP was wondering about.

There is no mention of fillers and such to prevent the dreaded "flash ignition/detonation" that is often mentioned here and elsewhere on the web.

Here is a pic of 10 grains of Green Dot. It fills the 308 case about 1/3. It doesn't look like enough powder to knock a sick whore off a piss-pot, but it apparently will move a nearly 200 gr bullet at 1200 fps.

IMG_2514.jpg

My theory on these low volume charges is that they use very fast burning powders for a very good reason. Nowhere have I seen any data for mini charges of 4831. jd
 
Wat exactly does it take to keyhole as I run up and down the powder scale from 9 to 18 gr. of Tral Boss in my .308 with 200 gr bullets and I never had this problem. I'm thinking its an internet myth .
 
Wat exactly does it take to keyhole as I run up and down the powder scale from 9 to 18 gr. of Tral Boss in my .308 with 200 gr bullets and I never had this problem. I'm thinking its an internet myth .

An unstable projectile. I think these were 90gn in a 1:12 .223, very repeatable, and you wouldn't want to get hit with one, but ehh, not what we're aiming for (excuse the pun)
 

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Google search "Trailboss PDF" will lead to single-page document published by IMR. Excerpt from said document:

"we have a formula for developing loads for all cartridges and it's simple to follow. This formula may be used in both rifle and pistol applications: Find where the base of the bullet to be loaded is located in the case and make a mark on the outside of the case at this location. Then fill the case to that mark with Trail Boss, pour into the scale pan and weigh. This is your maximum load. Pressures will be below the maximum allowed for this cartridge and perfectly safe to use! Take 70% of this powder charge weight (multiply the maximum load from step 1 by .7), and that is your starting load. Start with this beginning load and work up to your maximum charge, all the while searching for the most accurate reduced load. Once found, the fun begins!"

[Example of 9 gr to 18 gr range in post #24 falls outside parameters given by IMR]
 
Wat exactly does it take to keyhole as I run up and down the powder scale from 9 to 18 gr. of Tral Boss in my .308 with 200 gr bullets and I never had this problem. I'm thinking its an internet myth .
I ran Horn 170FP #3060 out of 20" 308. 9.6gr Trail Boss for 1048FPS. They did not keyhole, but the holes in target were not completely round. Definitely not stable, but shot accurate enough.
 
Maybe i'm not shooting far enough to let them tumble but at 30-50 yards it kills and is really accurate . I just wasn't sure were all this fear of striking your can on the way out of the barrel comes from ? Inches from the barrel and a bullet turns , or did the guy let the can loose on the threads. JD , those old books are good info and closer to the truth as the new ones are lawyer safe it seems.
 
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I use TB with 220 RN and they shoot one hole at 50 as will as 165 spitzers from a 20" 11 twist. Have not shot them farther
 

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