Potential Problem: 45 Auto, Unique Powder, 230 gr Bullet

[irobro]

I have sent several emails to Alliant Powder asking for comment but have not received a reply. The Alliant Reloaders Guide boldy warns readers not to exceed the charge weights printed in the guide but I'm having trouble deciding which recipe to believe. I would appreciate comments from forum readers. My email to them:

It appears there may be an error on your website Reloader's Guide. The three copper 230gr bullets that you provide recipe's for have charge weights that vary widely: 6.5, 6.0 and 7.3 grains respectively. That's a 20% variance with jacketed hollow point the lowest at 6.0 grains, and a copper plated bullet the highest at 7.3 grains. Logic says there is something significantly wrong. Please comment.​

 

[huntinaz]

Lot to consider besides just weight. Different shape, different bearing surfaces, different allow or plating vs jacketed etc mean different pressures and charges.

 

[Nick_C_S]

A 230 grain bullet is not just any 230 grain bullet.

One huge difference can be how deep the bullet sits inside the case. This reduces the internal volume available for propellant. In general, the less internal volume, the faster the propellant's burn rate - i.e. more pressure.

Speer #14 has separate data for their 230 round nose, compared to their other 230 profiles.

Whenever I get a new bullet, I always take and record their measurements. Most importantly, the dimension of how deep it sits in the case. For instance, with 357 Mag, Sierra's 158 JSP sits .345" deep in the case; Hornady's 158 XTP sits .370" deep. That's 25-thousandths difference. If I do a work up using a Sierra bullet, I can expect considerably more pressure if I simply switch over to a Hornady XTP; and doing so is ill-advised. A reduction in charge would be in order.

 

[rg1]

I've loaded several different 230 gr. bullets in 45 ACP, plated, jacketed HP and RN, and one lead 230 gr. In all I see 6.0-6.1 grains of Unique to be a good reliable load. Highest charge for me has been 6.5 grains and I would not go higher with any 230 gr. bullet I reload. Remington's 230 Golden Saber, a brass jacketed HP gets a little more powder to get the same velocities due to it's bearing surface shape. I consult a lot of data sources and do not use data that's higher than the norm. Be very careful exceeding 6.5-6.7 grains with any 230 gr. bullet and a lot less hammering on your pistol and brass if you keep charges near 6.0 grains of Unique. Alliant data used to be more reliable for various bullets especially when they were Hercules. Now most of their data is for Gold Dots and TMJ which often doesn't relate to other bullets. I don't use Speer data unless shooting their bullets, just me.

 

[Unclenick]

Yes to Nick's information!


Irobro,

Constant charge with bullet weight depends on the bullets all having the same seating depth in the case. But many of the hollow point designs have such blunt nose forms that they won't feed properly when they are seated out to the maximum COL for a round nose bullet. So they seat them deeper. Powder charge has to be reduced some so doing that to avoids excessive pressure.

The other factor is bullet hardness. A plated bullet, like a Gold Dot or a Ranier or a Berry's plated bullet offers less rifling engraving resistance, so they produce lower start pressures. For that reason the powder doesn't burn as fast early in the firing event and the bullet is further down the barrel when the pressure peaks. The additional space behind the bullet due to its moving further forward¹ means the powder is burning in a larger volume. This is why the plated bullet loads call for more powder².


¹The powder burning space increasing because of the bullet moving forward is called expansion.

²With more expansion you need more gas to achieve a given pressure, and it takes more powder to make that additional gas.