45 Colt case capacity variations are LARGE!

[bgokk]

If someone is loading at or near maximum charges the difference could result in a KABOOM!

I was going thru some cases and noticed that there is about 3/16” difference in depth between F C (that’s F space C) and F-C (which is F dash C) head stamps. F C has a thicker web. I also found that W-W & F-C are the same depth.

To arrive at this startling information I used a highly scientific tool – a wood dowel tapered on one end so it would reach the web of the case.

Using this tool I also found that WINCHESTER brass is about half way between F C and F-C/W-W.

I tried to post this about noon today, but was unable to insert the JPG of this complicated tool.
The top line is the depth of F-C/W-W. The middle line the depth of WINCHESTER. The bottom line is F C. I know about using water to determine case volume, but this is so graphic.

[flyingmonkey35]

Kaboom!!!!

[Dale53]

The difference in case capacity can also vary between cases with the same head stamp but made at different times.

Just another reason not to load "balls to the walls" for most of your ammo...

FWIW
Dale53

[Mach_Cat]

herters brass seams to have less capcity. when running brass through my dillon 650. the herters will ring my alarm for over charge. I pull the case out and weigh it exact on the money. Almost every herters case rings the alarm. Also a pain to reprime. been pulling out all the herters now and just setting them aside. Maybe make wax bullet blanks out them!

[dubber123]

I found out accidentally, and luckily with no harm to my 625, that my particular lots of FC and RP brass were enough different that the FC cases matched the velocities of the RP brass with 1.5 grains LESS powder.

[Idz]

Case capacity is usually measured by filling it water and then weighing how much water it holds. A depth gauge doesn't account for the odd shapes at the bottom of the brass drawing near the head which vary between manufacturers.

[bgokk]

The difference in case capacity can also vary between cases with the same head stamp but made at different times.

Just another reason not to load "balls to the walls" for most of your ammo...
+1....

[Outpost75]

Weigh the cases, then reduce the powder charge by 10% of the difference in average case weight, to compensate for heavier brass of the same caliber, which will have less capacity.

[220swiftfn]

Then again, with SAAMI specs of 14,000psi in a case designed around the bulk of black powder, you're not going to get in trouble with book loads......

Now if you're loading "Ruger only" loads, you might want to pay attention to the components used (and reduce loads as needed)....


Dan