logic check

[shu]

after a couple of years having fun reloading, messing about with different powders and bullets, puzzling over wide variations in published load data for the seeming same combination of bullet and powder, and just gathering numbers because it is what i like to do, i am asking myself: "where am i going with all this?"

what am i trying to achieve, and what is a logical sequence of steps to get there?

accordingly i sat, thought, and came up with the following progression, which i offer for comment or criticism.

for present, i am mostly interested in getting best accuracy at target pistol for modest cost. that means plated bullets of medium to low weight, at medium to low velocities. however i wanted to come up with some general guidance i could follow in developing a load for any purpose.

the last piece to the puzzle, about which i am most interested in getting comments, came as the thought that all powders will give a cleaner and more consistent burn as pressure increases. therefore plan to run the powder toward the high end. for any bullet and barrel, highest velocities will come from slowest burning powders. if less velocity is wanted (for softer recoil or because bullet is not stable at higher speed) then use a faster buring powder; plan still to run it toward its high end to keep pressure up, burn clean and consistent.

this of course presumes quality firearm in good condition.

==========

if at any time there are indications of overpressure - flattened primers,
difficult case extraction, or it just feels too hot - then stop and back off.

1. select bullet (weight, material, profile) for intended purpose.
2. select muzzle velocity (low recoil, long distance, power factor).
3. review available data, select powder expected to give that velocity at near max load. (reasoning: variations in velocity should decrease as pressure increases. this presumes pressure capability of weapon is not in question.)
4. select oal. (if published oal for the exact bullet is not available then
use at or longer than nearest compatible bullet for which published oal can
be found, yet not so long as to touch rifling or cause chambering problem.)
5. select cases of same headstamp. (for pistol cartridges at low pressure
it may be safe to mix cases; but we seek to operate near the pressure limit,
moreover we seek to minimize factors which may cause velocity variation.)
6. crimp; the minimum which will prevent bullet setback. (while firm crimp
promotes higher pressure and therefore more consistent burn, we want to
avoid unintended deformation of case or bullet.)
7. beginning at published starting powder load (or 10 percent below published maximum) construct strings of cartridges for test. use higher standard of quality control (bullet, case, seating imperfections) than general production.
8. measure muzzle velocities of test cartridges; evaluate mean, spread, and
standard deviation of the strings as powder load increases.
9. for best powder load (lowest velocity spread and standard deviation)
build another test string and fire for group size.
10. if desired, explore different oal. (if oal is shortened, back off the
powder and work up again.) construct and fire test strings first for velocity
and then for group size.

 

[Kamicosmos]

Sounds about right. Pretty similar to my reloading goals, in fact.

 

[stans]

Well, for best accuracy, I have not had the best results with plated bullets. I find I get better accuracy from plain lead, properly sized so they are 0.001" over groove diameter or traditional jacketed bullets sized to match groove diameter.

 

[Jaywalker]

I don't load for handguns, so I can't speak to that aspect of it, but this sounds similar to the threads like, "How to choose the right powder..." I like your list.

I'd add that, at least in rifles, more powder is better - it gives a more even burn. "Load density" of 90% or better allows the primer to ignite the powder the same way each time, rather than some across the top sometimes and sometimes just near the head.

I also look at the pressure at max, even if I don't intend to get all the way there. The pressure listed is an average of several shots - the closer it is to the SAAMI max, the less variation you can infer from the tested shots. Again, a rifle example - a SAAMI max of 54,000, and one load shows 51,000 test average, and another shows 52,000. The one with 52,000 showed less variation, and that load's individual shots didn't exceed the 54,000 SAAMI max. With no other info, we could assume a more consistent burn.

I like choosing powder/bullet combinations that are either common or recommended in the manuals. At the least, it allows plenty of cross-check capability in multiple manuals - they're often quite different. As to that, reloading manuals are like any other reference material - the newer the better. There've been some changes - sometimes lower and sometimes higher - recently. It's wrong and dangerous to assume that these changes are a result of fear of lawyers. There's been a lot of work with piezo testing equipment recently that shows that some standard loads in the past had some stiff pressure spikes that didn't show up with the older crusher tests.

I'd caution that we don't assume a linear burn rate, however. I think there's a good chance that the powder makers concoct coatings that burn most evenly near their max pressures.

Jaywalker

 

[halvey]

I think first is to really think about what you want to accomplish. I cut down my calibers over the years greatly. I mean, with reloading, you can accomplish the same things as by going with another caliber.

Sometimes we tinker too much at the bench and don't get out and shoot enough.

I only load for 3 calibers. I can see myself actually loading for a couple more only in the future.

For my .380, I need a hot carry load and a mid range practice load.
For my .45, I need various loads (pins, plinking, idpa etc), but they can be pretty much accomplished with one powder.
For my .308, I'm thinking my target and hunting loads will be pretty much the same.

In reality, that's not a lot. Once I got the load, not a whole lot of tinkering needs to be done.

From there, your steps are right on.