Advice on QuickLoad re Powder Compression

[South Pender]

I’ve been working with QuickLoad to find good powders for some upcoming reloading projects and have come up with a question:

When I enter a powder and look at the results for various weights of powder, I sometimes find that the last “Near Maximum” just before “DANGEROUS LOAD-DO NOT USE!” will be with a charge weight that shows the ”Filling/L.R.” as being over 100%. So this would seem to indicate a compressed load. My question is what amount in excess of 100% would be seen as a reasonable compressed load. For example, would a load showing a Filling/L.R. of 103% represent too much compression resulting in broken powder kernels? As I understand it, a general principle of reloading has been that charges that fill the case often result in best accuracy. How much compression can we get away with before going too far?

I should add that I haven't actually tried to charge any cases with an over-100% charge to see whether a bullet can be seated, but have wondered about this. Any insights on this?

 

[Lkwebb]

Quickload is a lil bit on the conservative side IMO.
When testing a load even with quickload in the higher capacity still comes down to watch for pressure signs. Go up a lil at a time.
My 6ppc I use 29.1 grains n133 and it shows 110.3 filling capacity but it's right at the shoulder
Are you using optimal barrel time to get you close to your node window.

 

[Laurie]

Those few manuals that let you know that some charges are compressed quote loads that can go as high as 115% fill-ratios. This particularly applies to Nosler data. Heavy compression (110% and up) appears in the Nosler data for both types of powder, extruded and ball. Traditionally, manuals warned against compressing ball powders for various reasons, but only Norma does that anymore.

I had a look at this last year:

http://www.targetshooter.co.uk/?p=3543

 

[Lkwebb]

Here is a obt chart if you would like to try it...

 

[Jager]

I generally run compressed loads up to about 104% or so. You can go higher, but as compression increases, there is more and more pressure exerted on the base of the bullet. At some point your seating depth becomes unstable, resulting in the bullet being pushed back out some unpredictable amount.

What that point is - the crux of your question - will vary depending upon caliber, the amount of bullet shank seated into the neck of the case, case elasticity, the type of powder... and probably a couple other things.

When running a powder chart in QuickLoad, you can set the maximum amount of compression you want to see.

 

[CharlieNC]

You sure the warning is not for pressure instead?

 

[jepp2]

You sure the warning is not for pressure instead?

This ^^^^^^^^^^

 

[South Pender]

You sure the warning is not for pressure instead?

Not sure what you mean. For the loads I've examined, the "Near Maximum" charge indicates a safe load pressure-wise. For those loads, the QL output shows a percentage of fill. Sometimes, the maximum safe load has a ”Filling/L.R." over 100% This is not a warning, just useful information. My concern is how much over 100% can you go (with safe pressures) before compromising the load from excessive compression.

Laurie, that piece your wrote in Target Shooter is really informative. Thanks for that. I take it that you consider a Filling/L.R up to 105% as mild compression. I'll keep that in mind.

 

[Laurie]

I take it that you consider a Filling/L.R up to 105% as mild compression. I'll keep that in mind.

Yes, that's my entirely personal and unofficial definition. I run cartridges with this degree of compression - and a bit higher too - all the time. Everything I load these days seems to require powder up the case shoulders.

 

[dellet]

It all will be powder dependent.

If you do a bunch of models it might start making sense of some kind. Examples might be using a pistol powder like Red Dot in a 308 case. You will probably reach max pressure warnings before the case is 50% capacity.

Accurate 2015 in a 22 Hornet case might need 200% to make Maximum pressure.

Some compression warnings are mechanical vs safety issues. Fine ball powders, if dropped though a tube slowly settle very tight. You almost can’t compress them. Like trying to compress a sack of cement. Thus can damage the bullet or expand the case before it will compress. If it deforms the case it can jam or raise pressures even more due to no chamber clearance.

Stick powders can drop so poorly that to sometimes get near 100% density with a seated bullet, you would need to crown the powder over the top of the neck and force the bullet to compress the powder into the case.
Black powder shooters use a compression die specifically for this purpose. That much compression on stick powders breaks all the sticks.

It’s a bit by design that max loads for powders in a given cartridge have a correlation of both pressure and density.

If you compress powders with light neck tension, leave them to sit over night. The recheck seated depth. Often the powder will push the bullet out.

Trail boss compressed is famous for this.

 

[Laurie]

One point to note in all this is that the Redding Competition seater die must not be used on compressed loads. Doing so on anything other than very light compression damages the seater stem and Redding will not replace it FOC as they warn against the practice.