Chamber Pressure Revelations

[1Shirt]

Got my new Handloader in the mail today with Terry Wieland's article "Chamber Pressure Revelations. Probably the best article on the issue that I have seen todate. This is due as Weiland explains that all the previous articles, and they have been numerous have been loaded with Academic gobblygook, tables, and expirating data (at least to me).

This article is much better and is written on more of a handloaders realistic, and understandable basis. It has pic of a ctg (cutaway) with a minimal charge of powder, and what appears to me to be a representation of 311291 cast w/GC.
However, the article is written referencing jacketed bullets and Secondary Explosion Effect (S.E.E.) Unless I missed it, I found no reference to the issue with cast blts specificly.

12 areas are covered, with Part 13 being the conclusion. I found the reference in Part 3 on "Jackets" and their thickness to be most interesting. Specificly, he states in reference to Dr. Brownell isolated findings that "To his suprise, he found that softer sackets lead to higher pressure not lower." AND:
"In one test, two otherwise identical bullets produced a difference of 7,000psi chamber pressure, purely because of differences in their jackets." It would be interesting to see a similar test in cast bullet hardness between say 18 BH and 28-32 BH.

The other area Part 7, :Freebore, is also quite interesting to me. He references long bullets seated to minimal freebore can increase dramatic pressure increases. Think all of us who have been around the block a few years worth can equate to that. However, am quite sure that even the hardest cast projectile, loaded to minimal freebore cap would not be as near a problem as it would be with jacketed.

All parts of the article have merit, but it was the parts listed above that I found the most interesting. Am sure that others may find different parts of equal interest. Anyhow, it is the best article of its type that I have read in any gun mag in many years. Even if you are not a subscriber, it is worth a trip to the local news stand to pick up a cy of the Dec. 2012 Handloader.
1Shirt

[popper]

"Jackets" and their thickness to be most interesting

I read an army ordnance article that leads me to believe the pressure theory. Thin jacket lets the soft core squish and plug the bore tighter. COF is the same but more lateral pressure is applied. For CB, I'm guessing that the 'excess' lateral pressure causes the nose to grow - slump- or the length to change. So yes, pressure in the bbl would be higher but not near the magnitude of jacketed. Foggy memory but I think the lateral force was ~ 1/5 of the base force in the army test.

[Von Dingo]

In the late 1990's Midway came out with four caliber specific reloading books for the component slugs they carried. The calibers were for 9X19, .357 Mag, .44 Mag, and .45 ACP. The slugs are each shown with several to maybe eight powders. The differences in pressures between slugs that weighed the same was amazing. You don't have to worry about me changing components with published data and max powder charges all willy nilly.

Looking forward to the new issue of handloader, like always.