Thread: 6.5x55 SE Sanity Check

Originally Posted by Jhon

Pressure and velocity do not run hand in hand. A lower velocity load may have higher pressure, or even a pressure spike, for a number of reasons.

Just some clarification on my prior statement. It is specifically referring to two cases with similar volume (<10% difference) running the same powder. Correct me if I'm wrong but unless you have an under fill situation (below book minimum) or are seeing pressure signs the relationship is close to linear. I know there are some powders which are notorious for pressure spikes but I believe 2209 and 2213SC aren't.

PS: Also haven't jammed the bullet into the lands, or compressed the load.

Originally Posted by Woody

I use 44.6 2209 with both 143eldx and Sgk 140 sbt. 0.4- 0.6 moa @ 300m. S&L classic dl.2750fps mv.

What barrel length?

24"

Originally Posted by Magnetite

Just some clarification on my prior statement. It is specifically referring to two cases with similar volume (<10% difference) running the same powder. Correct me if I'm wrong but unless you have an under fill situation (below book minimum) or are seeing pressure signs the relationship is close to linear. I know there are some powders which are notorious for pressure spikes but I believe 2209 and 2213SC aren't.

PS: Also haven't jammed the bullet into the lands.

To be honest mate I'm quoting something I learned elsewhere rather than by experience. The point made was that pressure can vary widely and separate to velocity for a number of technical reasons. That is, you cannot rely on an increase in powder that gives a linear increase in velocity to also give a linear increase in pressure. This is the key issue of going beyond published data. If the published data gives a velocity that one would like to improve on, and the indicated pressure is below published max for the cartridge, folk tend to assume a few steps above published load data will increase velocity and pressure at the same relative rates. This is not necessarily the case. While US liability realities might mandate large margins for error, we clearly go beyond published data at our own risk. Without being able to see what happens to pressure there is a real risk of crossing the line if we assume a linear relationship. Of course we still do it. Hopefully with a piece of string operating the trigger lol. I made the comment because I think its important to acknowledge in a forum, where the risk lies. There is no telling who will come along and read a thread and get the wrong end of the stick. Hope you don't mind. Watching with interest. J.

Norma brass.

Originally Posted by Woody

I use 44.6 2209 with both 143eldx and Sgk 140 sbt. 0.4- 0.6 moa @ 300m. S&L classic dl.2750fps mv.

Same rifle, same accuracy, 140 AMax or Berger or SST, N560, 2840fps
Bloody wonderful.

If it wasn't illegal to only own one gun, this would be my only one.

Originally Posted by Jhon

I made the comment because I think its important to acknowledge in a forum, where the risk lies. There is no telling who will come along and read a thread and get the wrong end of the stick. Hope you don't mind.

I don't mind at all. Hopefully I have been clear enough (In my first post I mentioned it's over max and again when I posted over max data).

Originally Posted by Jhon

The point made was that pressure can vary widely and separate to velocity for a number of technical reasons. That is, you cannot rely on an increase in powder that gives a linear increase in velocity to also give a linear increase in pressure.

When venturing past max, my new approach is to cross reference with Gordon's Reloading Tool and data from previous testing. But yes it is very much at your own peril.