Conflicting reloading info

[slow1911s]

Originally Posted by rvb

since you guys seem to like analogies.... it's more like... how would you know your car is dangerously close to over heating w/o a temp guage... all appears fine until things blow and steam comes out from under the hood.

As far as "driving with traffic" ... how do you know how fast your target velocity is? Well, you can buy some factory ammo of the same bullet weight to chrono and get a starting point*. It's not an end-all goal based on powder burn rate, but it'll get you a comparison point.

A chrono can tell you a LOT about your load. I always start significantly (use some common sense for exact #s) below the middle of the book load. Or in this case w/ wildly different book loads I start near the bottom of all the data. Load in steps up to your target load, and then somewhat above, with enough of each for re-tests/etc.

As you work up in loads, you should see velocities increasing roughly in proportion. If you see that you are increasing powder w/o a corresponding increase in velocity, you are probably close to exceeding max pressure. Some powders will even slow up as powder is increased when you're getting into dangerous territory. I like to go past my target charge to continue to look for these warning signs, so I know if I nearing the max. It's not the end-all of safety steps. you still have to watch for primer flow and bulges in un-supported portions of cases and know what you'd expect in terms of recoil, etc etc.

Another key thing the chrono tells you is standard deviation... ie how consistent your loads are. This has less to do with powder charge and more to do with bullet consistency (imo), oal, crimp, etc. For pistol, I like to see single digit SD.

It's bad enough that most books never seem to have THE bullet you want to use... now if two books are all over the place in data, you'll have absolutely NO idea what your load is doing w/o a chrono.

some data is better than none.

-rvb

*with some powders you may never get to factory load velocities w/o exceeding pressure max.

Folks - listen to this man. If you're gonna reload - you need a chrono.