Also worth noting, Berger developed their entire printed manual with simulated data from QL
That would explain why their data is all over the place.
The World of Cartridges and Compromises........
- Thread starter c-fbmi
- Start date
That would explain why their data is all over the place.
good post thanks. Nice to see others starting low and working up. There is no safe shortcuts when it comes to load development
Dorian Gray
CGN Ultra frequent flyer
This is all well and good but will your load pressure determination methods work well on my new savage in 270 winchester?
- Location
- Somewhere on the Hudson Bay Coast
That is exactly what I'm saying. I don't recall the exact load that KABOOMed, but I had started 5 grs low, and increased in one grain increments, all in the yellow on Quick Load. The bullet was the 380 gr Rhino. The round I fired before the KABOOM clocked 2350 fps; the same velocity I had with my working load in that barrel using Hybrid 100. When I began using the 380s, I used 4350, and the maximum load produced 2300, switching to the slower burning Hybrid 100 gave me another 50 fps, so the Quickload prediction of 2400 fps from a 20" barrel with Retumbo didn't seem unreasonable, but if I had hit the wall at 2370, or less, then that's what it would be. The velocity increase between increments progressed as expected, and there was no reason not to fire the next load increment above 2350. After all, I had fired the load increment above 2350 when I worked up the Hybrid load, and determined that the 2350 load was to be my working load. As I assembled each load, I had written the charge weight on each cartridge with a sharpie, so there was no chance of loading the wrong cartridge. On the KABOOM shot, the velocity increased from 2350 to 2550; it makes me wonder what the velocity might have been if the rifle hadn't failed.
The only explanation I have for the occurrence is that once 100% load density was exceeded, the pressure curve rose sharply, and unexpectedly from the standpoint of charge weight, but obviously not from the standpoint of powder volume.
As an interesting aside, I was never able to get the case out of the chamber, its still in there. I tapped the flash-hole, which was enlarged to the lettering on the case head, and the bolt pulled the head off the case. Then I carefully threaded the inside of the case body, and the bolt simply pulled the threads. Finally I epoxied a .300 Winchester inside the Ultra case, gave it 24 hours to fully cure, and when I attempted to tap it out, the .300 case came out, but not the Ultra case.
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Boomer, I have given this a lot of thought since we had discussed this a couple years ago. I have come to a suspicion and question regarding this incident..........is it possible you got an oversize or misformed bullet that was heavily jammed into the leade? I know this happened to you and I believe that you did exactly as you have described with 1 gn increments, but I still have a hard time reconciling the spike with exclusively the powder charge as the cause. I suspect there were other unknown forces afoot.......
This is all well and good but will your load pressure determination methods work well on my new savage in 270 winchester?
A "Salvage" and in "270 Win".......better stick with the manuals there DG, even then you should be afraid...........
- Location
- Somewhere on the Hudson Bay Coast
It doesn't list the Rhino bullet, but there allowances in the program to enter bullet caliber, weight, and length.
- Location
- Somewhere on the Hudson Bay Coast
While I can't answer that question absolutely, I'd have thought that a bullet that different from the others would have caught my attention, certainly when seating. I remain convinced it's connected to the reduction of powder capacity within the cartridge.
In blasting though, we have a cute little term called critical density. If an explosive is compressed beyond its critical density by the detonation of an explosive in an adjacent hole, it is unable to detonate. Now this might be a stretch, but if the powder in the neck of the cartridge deadpressed, forming a plug, perhaps its possible that the gas pressure built up behind the plug until it couldn't be contained.
- Location
- Somewhere on the Hudson Bay Coast
I crimp my bullets, and the Rhinos have a good crimping groove, so I don't think bullet jump is a possibility. That rifle shot like a varmint rifle, but I didn't have to turn necks, so I think the throat was in spec for a hunting rifle.
This is sure a remarkable thought and how often could it or has it happened at the brink of destruction?
When trying to figure out what happens on ignition in instances where things go wrong, I like to fall back on some proven facts.
The British proved, back before WW1, that when the 303 cartridge was ignited in the Lee Enfield rifle, things happened so violent that the base of the bullet started to move before the nose of the bullet did.
Another fact is with a bottle neck cartridge, the bullet will have reached the sped of sound by the time it has travelled about one inch, or maybe in some cases, slightly more.
To my mind, this completely rules out any thing about something, crimp or otherwise, holding back the start of the bullet, or by the bullet hitting the lands, then stop, while the pressure builds up.
The powder ignites and the bullet is gone. Period.
Another thing we hear a lot about is a plug building up in the neck of the cartridge, as the powder is pushed forward, then pressure build behind it. This was all the rage on the CGN about three years ago and lack of a proper primer was blamed for the resulting Kaboom.
So I ran a test. I don't have my notes in front of me, so can't remember the exact rifle I used, but I think it was a 30-06. I used a slow burning powder, I think either 4350 or H4831 and used about 2/3 of a case full. I loaded one each with a standard pistol primer, a magnum pistol powder, a standard rifle primer and a magnum rifle powder.
I drove out a bush trail and found a green douglas fir tree with a trunk of about sixteen inches across. I tied the rifle to the tree, pointing straight down, with a cord from the trigger that I could pull, while standing on the opposite side of the tree.
I loaded the one with the magnum rifle primer, and pulled the trigger cord.
There was a normal boom and a hole in the ground where the bullet hit. The empty case looked like a case should look like after firing a light load.
I fired each of the others, going down in primer strength, until the standard pistol primer made no noise, but the primer had fired. When I later took the cartridge apart, it simply had failed to ignite the powder. There was no discernible difference between any of the fired cases. Just cases that had been fired with a light load.
So I am REALLY SKEPTICAL about a full charge pushing the powder forward, making a plug, then have the charge go KABOOM.
In real life I just don't think that happens.
The British proved, back before WW1, that when the 303 cartridge was ignited in the Lee Enfield rifle, things happened so violent that the base of the bullet started to move before the nose of the bullet did.
Another fact is with a bottle neck cartridge, the bullet will have reached the sped of sound by the time it has travelled about one inch, or maybe in some cases, slightly more.
To my mind, this completely rules out any thing about something, crimp or otherwise, holding back the start of the bullet, or by the bullet hitting the lands, then stop, while the pressure builds up.
The powder ignites and the bullet is gone. Period.
Another thing we hear a lot about is a plug building up in the neck of the cartridge, as the powder is pushed forward, then pressure build behind it. This was all the rage on the CGN about three years ago and lack of a proper primer was blamed for the resulting Kaboom.
So I ran a test. I don't have my notes in front of me, so can't remember the exact rifle I used, but I think it was a 30-06. I used a slow burning powder, I think either 4350 or H4831 and used about 2/3 of a case full. I loaded one each with a standard pistol primer, a magnum pistol powder, a standard rifle primer and a magnum rifle powder.
I drove out a bush trail and found a green douglas fir tree with a trunk of about sixteen inches across. I tied the rifle to the tree, pointing straight down, with a cord from the trigger that I could pull, while standing on the opposite side of the tree.
I loaded the one with the magnum rifle primer, and pulled the trigger cord.
There was a normal boom and a hole in the ground where the bullet hit. The empty case looked like a case should look like after firing a light load.
I fired each of the others, going down in primer strength, until the standard pistol primer made no noise, but the primer had fired. When I later took the cartridge apart, it simply had failed to ignite the powder. There was no discernible difference between any of the fired cases. Just cases that had been fired with a light load.
So I am REALLY SKEPTICAL about a full charge pushing the powder forward, making a plug, then have the charge go KABOOM.
In real life I just don't think that happens.
- Location
- Somewhere on the Hudson Bay Coast
Bruce, its not a question of the primer pushing the powder column forward creating a plug, as can happen with small charges of slow burning powder. The term dead pressing means the critical density of the energetic material has been exceeded, and it can no longer function; it has become inert. When a bullet is seated on a cartridge case full to the mouth with powder, the compression of that powder column is not uniform. If you've ever pulled a bullet from a compressed load some days, weeks or months after it was loaded, the powder from the base of the bullet to the shoulder of the cartridge has formed a solid, and you have to pick away at it, before it loosens enough to pour out, but the portion of the powder column below the shoulder pours out normally. Thus if dead pressing can in fact happen to smokeless powder, and I don't know that it can, its possible that the solid mass of compressed powder in the shoulder area of the case formed a plug that wouldn't burn, at least not at the normal rate, and pressure built up until beyond the strength of the containment.
It should be noted that the conditions that were present at the time, were in no way standard. The bullet weight exceeded that standard for the .375 by 80 grains. The powder was unusually slow for the caliber and case capacity, which normally performs well with burning rates between 4350 on the fast side and H-4831 on the slow. Additionally the powder was compressed to an unusually high degree. Dead pressing, if its chemically possible, is best explanation of the incident I can think of, but if there's a chemical engineer out there, maybe he could say yea or nay. Perhaps I'm out to lunch on the dead pressing concept, but thinking on it, if a granular propellant has pressure exerted on it until it forms a solid, that in itself might be sufficient to alter its burning rate. If due to the extreme compression a less-flammable plug was formed, its conceivable that pressure could build behind this plug, from the portion of the powder column that burned normally.
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- Location
- Somewhere on the Hudson Bay Coast
Tried it. Tried it at -35 too.
Well Mike, something very unusual happened, for sure. I know your point, we have talked about it before, but I just can't get my head wrapped around the compressed plug theory.
The major reason for me being skeptical, is the fact that millions of very similar conditions have regularly been loaded. That is, very high compression of slow burning powder in a great many different calibres and arrays of bullet weights. So, if that was the cause there would be Kabooms all over the place.
Jack O'Connor's load of 60 grains of war surplus 4831 powder in a 270, with a 130 grain bullet was typical. 60 grains filled the case right to the top. I used to tap the side of the case to lower the powder level a bit, so there was a tiny bit of room to start the bullet and the 130 grain Norma semi boat tail that I commonly used, is a pretty long bullet. When the bullet got seated full in, you held the press handle for a bit and eased it off, to see if the bullet was going to come out a bit, when the pressure was released.
Jack even wrote that 62 grains made a better load than 60, if you could figure out how to get all the powder in!
I used to force a flat base 100 grain bullet into an over flowing case of H4831 in a 243 case. That's a pretty heavy bullet in 243.
And still no Kabooms.
Could the problem have been Retumbo powder, as has been suggested?
The major reason for me being skeptical, is the fact that millions of very similar conditions have regularly been loaded. That is, very high compression of slow burning powder in a great many different calibres and arrays of bullet weights. So, if that was the cause there would be Kabooms all over the place.
Jack O'Connor's load of 60 grains of war surplus 4831 powder in a 270, with a 130 grain bullet was typical. 60 grains filled the case right to the top. I used to tap the side of the case to lower the powder level a bit, so there was a tiny bit of room to start the bullet and the 130 grain Norma semi boat tail that I commonly used, is a pretty long bullet. When the bullet got seated full in, you held the press handle for a bit and eased it off, to see if the bullet was going to come out a bit, when the pressure was released.
Jack even wrote that 62 grains made a better load than 60, if you could figure out how to get all the powder in!
I used to force a flat base 100 grain bullet into an over flowing case of H4831 in a 243 case. That's a pretty heavy bullet in 243.
And still no Kabooms.
Could the problem have been Retumbo powder, as has been suggested?
All Retumbo loads from Hodgdon.com :
243 Win 105 Amax, 49.0grs -- 109% load density
25-06 120gr Swift A-Frame, 60.0grs -- 109%
270WSM 140gr Swift AF, 71.0grs --106%
7mm SAUM 175gr Interlock,66.0grs -- 109%
7mm Rem Mag 150gr TTSX, 73.5grs -- 107%
300 Win Mag 208gr Amax, 81.0grs -- 110%
300 Win Mag 230gr Berger , 77,0grs -- 107%
338 RUM 300gr SMK, 90.5grs -- 107%
338 Lapua, 210gr Partition, 102grs -- 111%
338 Lapua, 300gr SMK, 94.0grs -- 112%
dozens of more examples on their list of pressure tested data -- http://www.hodgdonreloading.com/data/rifle
243 Win 105 Amax, 49.0grs -- 109% load density
25-06 120gr Swift A-Frame, 60.0grs -- 109%
270WSM 140gr Swift AF, 71.0grs --106%
7mm SAUM 175gr Interlock,66.0grs -- 109%
7mm Rem Mag 150gr TTSX, 73.5grs -- 107%
300 Win Mag 208gr Amax, 81.0grs -- 110%
300 Win Mag 230gr Berger , 77,0grs -- 107%
338 RUM 300gr SMK, 90.5grs -- 107%
338 Lapua, 210gr Partition, 102grs -- 111%
338 Lapua, 300gr SMK, 94.0grs -- 112%
dozens of more examples on their list of pressure tested data -- http://www.hodgdonreloading.com/data/rifle
