alton9 said:
Savagedasher,
Why would you reduce the load to 35 gr? As I posted earlier, I'm afraid that would put me pretty close to .223 velocities. Am I missing something?
While I can appreciate the desire to "fix" the problem without burning hundreds of dollars in components, sometimes more data for an improved diagnosis is needed and thoughts of going directly to a fix are overly optimistic.
You've already got accuracy and velocity data for 37 grains. Shooting one five shot group with 35.0, 35.5, 36.0, and 36.5 grains and recording mean, SD, and ES along with group size and relative location at 300 yards will tell you a lot with minimal risks of creating over pressure conditions. In contrast, going above book max in hopes of a quick fix is ill-advised. I think you said you were using full sized not previously fired Win brass, so you've had minimal opportunities to see loose primer pockets or some other pressure signs in the brass. CCI primers don't tend to flatten until pressures are really high.
You are mostly inferring safe pressures from low velocity readings on an unproven inexpensive hobbyist chronograph. Well, you can't get high velocity without high pressure, but you can sure get high pressure without high velocity.
I would not say to never, ever, ever go above book maximums when reloading. But doing so requires the exercise of a lot of care and double checking. We do it from time to time in a controlled laboratory environment. When considering going above book maximum here are some things we carefully consider first:
1. What is the actual powder capacity of the chamber and brass under consideration. We measure the weight in water of ten cases that have been fired several times in the chamber.
2. How much extra case capacity is there due to OAL above that with which the data was developed?
3. Are there any signs of overpressure? Loose primer pockets after multiple firings? High pressure readings on a pressure sensor? Unreasonably high velocities for the cartridge, bullet, and powder?
4. Double check the reloading scale. Triple check the reloading scale.
5. Is the current book maximum the result of lawyering? Do earlier editions of the reloading manual show higher maximum loads?
6. Are there lot to lot variations of the powder that suggest we may be working with a slow lot where more powder is needed to achieve velocities safely achieved with this powder in the past?
7. Might the powder have absorbed some humidity and be reading a couple percent high in weight for the same amount of actual nitrocellulose?
We also remotely triggered above book loads until we could establish that pressures were safe.