Start Charge Weight Reduction

[leadchucker]

Some loading manuals just list a maximum charge weight, and simply suggest reducing that by 10% as a starting charge weight.
Some loading manuals list a maximum charge weight, and a starting charge weight, which is almost always about 10% less than the max charge weight.
I just noticed that most of the starting charge weights in the Lyman manual are at least 25% less than the starting charge weights. (at least for the pistol loads I've looked at closely.)

I'm thinking that might explain why I had so many unacceptably weak loads when I started loading, since I was basing the loads on data in the Lyman manual. Now, since I've started using data in some other manuals, I seem to start at a more acceptable load level.

Why are the starting loads in the Lyman manual so conservative?

 

[leadchucker]

Nobody?

 

[kingmt]

Because it gives a more true starting point instead of just a "should be a safe place to start".

I don't like beating up my guns so I go as low as passable. What beats up one pistol might not work there slide of the next.

 

[LiveLife]

Published load data pressure testings are typically done using testing fixtures and not actual pistols.

Technicians running the tests may list the start charges when chamber pressures start to be consistent and produce consistent shot groups. But of course this won't tell us if the start charges will reliably cycle the slides, extract/eject spent cases and reliably feed/chamber the next rounds from the magazines in our pistols with different recoil spring rates.

This is why we need to conduct our own full powder work up to identify the powder charges above the "start charge" that will reliably cycle the slide and then continue the work up towards max charge to identify the most accurate powder charge. Same goes for using published OAL - it won't ensure the listed OAL will work with your pistol/barrel/magazine so we need to determine our own Max OAL and then function check to determine the working OAL that will reliably feed/chamber from the magazine.

Benefit of having lower consistent chamber pressure start charges is for match shooting applications (like Bullseye competitions) where lighter recoil springs are used. The lighter published start charges will give the match shooters a solid charges to use instead of "guessing or experimenting" on their own.

When I conduct load development for a new bullet, to save time, I will use .2-.3 gr increments from start-to-high range load data to get me in the "ball park" of powder charges that will reliably cycle the slide then load .1 gr increment test rounds to determine what powder charge produces the most accurate shot group.