Anyone out there have a subscription to Handloader magazine? I have a trial subscription, but it doesn't allow me to access the full magazine online. There was an article in the latest issue - October - titled "Spurious Velocity Variations" that is very interesting. All the tests that the author ran did not identify the answer to the issue, but he says that he will follow up with lab tests (pressure readings, etc.) in a future issue.

If anyone out there has an online subscription to Handloader, could you please post a link to this article for the rest of the huntingnut members?

The gist of the issue / article was about one of three of the author's .357 Mag revolvers giving reduced velocity with an increase in powder charge when in combination with CCI 550 primers. He tried a few tests which seem to eliminate poor ignition as the issue.

The conclusions reached so far:
1) Not all guns behave the same in terms of accuracy, velocity and pressure with a given load.
2) If a load is not yeilding expected velocities, it is NOT always OK to increase the powder charge. In straight-walled magnum revolver cartridges loaded with older style spherical (ball) powders such as H-110, increasing that charge, in hopes of acheiving greater velocities, until the powder is compressed can result in pressure spikes that are dangerous - even to the point of possibly destroying the gun.
3) Internal ballistics can be difficult, even for experts with expensive, hi-tech equipment, so don't wander far from proven paths.

I found it very interesting that the effect of reduced velocity with increased powder occurred only in one of the three test revolvers and, in that revolver, only with one of the three brands of primer tested. This effect was repeatable - it happened the same way in repeated tests.

Also interesting were some of the possible variables that the author suspected, and the steps taken to eliminate them.

Marty, I am a fan of "Handloader"! I read the articles you mention and it just makes you go "Hmmm...." I'll be looking forward to the follow ups to see if he figures it out.

I'll have to find it on the news stand!

I had the same thing happen in loads for my .204 with 8208XBR powder ignited with both CCI small rifle mag primers and Rem 7 1/2 primers. At first I thought it was a problem with my chrono setup. I loaded some more rounds and repeated the test a few days later with the same results.

Oddly, this happened just with a series of powder charges around halfway between min and max. Velocities started climbing as expected from 3/4 of the way up the scale until max. From min charge to nearly halfway, the velocities also climbed normally with increased powder charge. Like the test in the article, extreme spread of chrono readings was very small within each group of rounds with the same charge, so I am guessing that poor ignition was not an issue (as did the author).

If he figures out what caused the velocity drop, and comes up with a solution, I will try to duplicate his process in my rifle. I don't think there will be a solution, though - just maybe a plausable explanation, when pressure curves are examined.

I stopped loading with the 8208XBR in my .204 as I was getting cratering in the primers badly enough that I was worried about excessively wearing the firing pin. There were no other signs that showed high pressure. The one thing that I didn't check for was residual traces of One-Shot lube on the cases.
I plan to try this powder one more time after I get a case tumbler. For now, I will stick with IMR3031, IMR4895 and IMR4064 which have all given me spectacular results.