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Maximum pressure for fast powders?

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31 August 2004, 00:35
DUK
Maximum pressure for fast powders?
Fast handgun and shotshell powders usually work at pressures up to 1000 bar (shotshells) or 2000 bar in Magnum revolver cartridges.

If one uses a fast powder like Blue Dot in rifle cartridges as discussed here on the board, at much higher pressures, is still safe or do these powders considerably change their burning characteristics?

The reason I am asking is that I developed two Blue Dot loads (thanks, Seafire), one for the 338 WM and the other for the 222 Rem. The 338 WM load with 36 grains and a 200 grain BT was calculated to be at 3650 bar, the 11 grain for the 222 Rem produce a primer picture which is not too different from a regular N133 load, I'd guess around 3000 bar. (Remark: 1 bar is 1 kg/sq.cm and corresponds roughly to 15.5 psi.)

I was told that the famous SEE only might occure with reduced loads and slow powders. However, is there anything else I should keep in mind?
31 August 2004, 01:29
Recono
I hope my answer is not the last or best on this subject, but I believe that if one were to plot charge versus pressure with one of the fast powders, one would find that pressure increases all too dramatically with charge weight. Unfortunately, other slightly unpredictable variables also affect pressure.

In other words, the charge weight and total conditions are too critical with the fastest powders. Best to stick with the tried and true. Experimentation is really not for those without pressure measuring equipment and a safe place to blow things up.
31 August 2004, 06:45
Recono
Quote:

Besides, exploring something new I admit might be dabgerous but is always exciting.



With reloading, it is not exploring; it is wandering around in a dangerous place with your eyes closed. However, it is not actually antisocial if done alone.
31 August 2004, 05:13
<eldeguello>
I cannot anbswer your question, but I can add one of my own: Why the hell would anyone want to use a shotgun/pistol powder in a high/power rifle cartridge?? Among other potential problems, the loading density is way too low for ignition/burning consistency!



As old Elmer Keith once wrote:



"O'Neil, Hopkins and I early learned thatcompressed or tight charges always gave more uniform velocities and better accuracy than loose charges of powder.



Airspace loadings of modern smokeless powders allow the charge to be thrown from one end of the case to the other as the muzzle of the rifle is lowered or elevated in firing, causing some variation in ignition and also combustion of the powders. I, for one, do not like airspace loadings in modern high-velocity cartridges. Smallbore rifles with large cases are the most dangerous to reload and largebore cases or straight cases seem never to develop the high pressures of bottleneck cases..."




31 August 2004, 05:54
DUK
eldeguello,

the reasons for this experiments are to generate a reduced load for the 338 WM, of course the tried&true would be 74 grains of RL19. This for our hunting conditions here with roe deer and hogs is just too much gun, I feel that with a heavy but slower bullet I could give some use to that rifle here as well.

Regarding accuracy, I found that BD with a density of about 0.5 is infact better than RL with about 0.9. I did have vertical stringing (which I think might be related to the powder�s position in the case) with the .222 Rem until reaching 10 grain, again a LD of about 0.5. There, the groups became smaller and more uniform.

Besides, exploring something new I admit might be dabgerous but is always exciting.
31 August 2004, 13:28
TBF
I only have one real experiment with Blue dot to relate

But the results were really impressive.
The estimated pressure of my loads in 300WSM ( indirectly calculated by measurement and observation ) was approximately the same as " normal " max loads of standard powder.

I did tip the rifle up and down to settle the powder in different locations in the case, I also stuck some rounds in the cooler during lunch. The chrono showed that the powder position was not very critical, and temperature was only somewhat critical.

Search for " Bluedot and 300WSM " or something similar and you will find my post.

Groups of sub .5 MOA are fairly common with this rifle and " normal " loads, Bluedot shot as well as the shooter could hold.

Travis F.