Home Forums Hunting & Shooting Ask The Gunwriters Reducing pressure on factory loads

Pretty much what I thought, you guys are talking about the engraving force rather than the reduction of case volume.

Exactly--and engraving force is the major factor in pressure/velocity until the bullet is seated VERY deeply--as the .25 inch shown in Dr. Brownell's 1965 study--which is MUCH deeper than most handloaders ever seat bullets.

Have wondered what the results of same test would be with some of today's even more progressive-burning powders.

The governing body for European ammunition manufacturers, CIP (the Commission Internationale Permanente) has considerable corssover with SAAMI on maximum pressures, partly because some companies are members of both CIP and SAAMI. Of course, some Euro-company might load ammo to higher pressures--but so can American members of SAAMI, as their standards are "voluntary." But not many members stray from the standards.

In the past I have been told by officials from both Lapua and Norma that they will, on occasion, make brass for each other. American companies have been known to do the same thing. But would like to hear how you know they're both owned by Hirtenberger (not Hertenberger),. There are all sorts of major companies in the ammo (and other business) that buy and trade smaller companies, and as far as I know neither Lapua or Norma has been part of Hirtenberger in the recent past--or even the same overall company. Lapua is part of Nammo, a Norwegian company, which also owns SK and Vihtavuori. Norma is part of RUAG, a Swiss company which also owns GECO, Rottweil and RWS.

That said, various holding companies keep buying and trading smaller companies constantly.

Sorry brain lapse it is Ruag owner of Norma/Lapua but I was thinking Herstal do they own Ruag or only FN Winchester? Is Hirtenberger still independent? I liked their ABC bullets.

I'm not sure that is a completely true statement. CIP and SAAMI both use Piezo Transducers to measure pressures, but their setup methodologies are different resulting in different pressures. I've been told that the SAAMI methodology tends to measure lower in identical cartridges than CIP methodology.

ChrisF,

Actually, an American piezo lab ran a test on that a while back. They set up their own pressure barrels, and decided to see if the CIP tranducer placement resulted in different pressure readings, as some people suggest. So they plugged the transducer hole in one of their barrels, then made another one with the CIP placement. The pressure readings were just about identical.

Thanks MrB...good to know.
I was actually told it's that CIP uses a drilled case, and SAAMI doesn't and estimates the offset of the brass obturation (similar to what I need to do with strain). I haven't hand calculated pressures in a while, but my memory says the offset I used for 223 (which is most of my testing) was ~3000 psi and suggested to me by Steve Faber. I thought I saw that Vaughn used similar in his experiments. I can only guess that SAAMI labs are taking a stock figure for brass offset as well which could account for some difference.

I'd seen measurements of the same load taken by CUP, SAAMI Piezo and CIP Piezo, each with a different value. Trying to remember who shared that factoid with me now.

The lab that did the experiment with CIP/SAAMI pressure methods uses a hydraulic press to test case thickness/resistance of that specific batch of brass before doing the test shooting.

At Barnes Bullets we manufacture some ammo for the European market so we have to perform CIP testing on it; drilling through wall of the case is part of the procedure. Also, we have one of the hydraulic presses used to test brass cases prior to testing for pressure and velocity.

Thanks MrB...I learned something new!

GSSP, curious what kind of values you get for the brass case deformation with the press?

Honestly could not tell you. I'm not the one who uses it.

Just pull the bullets and drop a gr or 2 of powder out and reseat the bullet. This is what I did with some Hornady 7mm-08 factory ammo that popped primers on the first 2 shots out of a Kimber Hunter I have.