Does anyone have inside info on why Underwood loads their 45 Super ‘down’ to 1100fps.
That’s roughly a 45 ACP+P. I’m inquiring about the penetrator so bullet deformity should not be an issue.

Buffalo Bore lists much higher velocities.

Underwood is a fine company and I’m expecting there is a solid reason for not pushing it to 1200 or more.
I’ve spent hours on reloader forums and 1100 is the low end.

I appreciate any insight you can offer or if there is an ‘in-house’ Underwood rep that would be great.

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Perhaps to keep them subsonic?

If you dig into their specs it’s listed as ‘subsonic’ but that may be a carryover from general description.
Of course it would depend on barrel lengths as far as subs.

I understand on their ‘defender’ offering staying at 1100 may prevent excessive penetration.
On an Extreme Penetrator one would ponder that they would want to max it out.  

It’s a guess on my part but I wonder if the powder they are using hits their pressure limit at 1100.

A screwdriver profile solid copper 200G at 1200 fps should be possible with the right powder.
Maybe it’s a liability issue but Buffalo Bore doesn’t seem to have a problem in that range.

This question has nothing to do with a proper personal carry round. I understand penetration windows.

It’s just about EXTREME PENETRATION. Real world application is not part of my curiosity. Simply from a ballistics standpoint why wouldn’t they drive the solid to the max?

I’m new to ‘Super’ and couldn’t find any Starline. My intent is to safely obtain 200G solids at 1200 if it’s practical. This is the best place I trust for the collective knowledge.

I’m a hillbilly. Explain why this would be a limiter please.

Solids don't swage into the rifling as easily as lead core so it can lead to pressure increases.

Both sensible answers I would have never though about.

Thank You.

Just looked it up. Extreme Penetrator Bullet Length is .696

For comparison of opposites looking at lead bullets.

45 ACP 200 Grain Round Nose Flat Point Lubed Bullet

Bullet Length 0.54 inches.

That’s a .156 difference in length. I would think the solid copper is at or nearing a compressed charge.
Mystery solved. Also as mentioned, copper being less malleable would be more pressure.

This also answers my questions about why Buffaloe Bore uses Hard Cast on their 1200+ fps.
Simply more room for powder increases velocity and less friction lessens pressure.

Thanks again for pointing out the obvious.