45 Colt Dies

[LAH]

Much has been said about the old Colt case being tapered. He back & forth on how sizing with a carbide die turns it into a straight case & it doesn't fit the chamber as it should. Since I was set up to load for the Colt I did the measurements for what they're worth.

[T. O'Heir]

The .45 Colt isn't tapered. http://stevespages.com/jpg/cd45colt.jpg

[LAH]

I love Steve's Pages. Lots of great information there. But I just measured some Remington factory loads I purchased in 1975. I didn't write the measurement but they are not .480" from end to end. Anyone have some they can measure?

[Real Gun]

I believe the .480 spec applies to sized, empty cases, not loaded ammo.

[LAH]

Thanks Realgun. At the VA now but maybe later I can measure the Remington loads. I'm not sure but these loads may have .454 bullets. And I may have some empty Starline brass to measure.

[Ole 5 hole group]

I don't have any new unfired 45 Colt cases to measure but it's my understanding that the factory cases do not have a taper - however, your cylinder does, therefore, your fired cases will have a taper and most, if not all, steel resizing dies won't return your fired case back to straight-wall. Normal carbide dies won't straighten the case either.

Redding makes a dual carbide ring resizing die that will properly resize your fired case. Doesn't really matter to most individuals shooting the 45 Colt, but for for some the $100.00 die gives them peace of mind.

[noylj]

One can always go to SAAMI for actual drawings.
One also compare a tapered case (see 9x19) to a straight wall case (which may have a 0.001-0.002" taper, if one wants to pick nits that makes it a tapered case--which rates right up there with calling the 9x19 a rimmed case because the rim is 0.394" and the case diameter just beyond the extractor groove is 0.391", ignoring all of that is simply due to the case taper--I'd love to see someone trying to headspace on a 0.003" "rim").
As far as the SAAMI drawing, the case body for .45 Colt is 0.480 +0.000/-0.006" with NO difference in dimensions from the end of the web to the case mouth. I call that a straight wall case.

[Clark]

SAAMI drawing looks like the chamber has .003" taper on each side when you go to cut it.
The cartridge looks straight.

{Edit: Clark, sorry but the SAAMI drawings all have copyright reservation posted on the bottom of them these days, so it violates the board policy on posting copyrighted materials to post them without express and credited permission. You can, however, post a link to the .45 Colt drawing on the SAAMI site.}

If I look at a 45 Colt chamber made by Colt in 1943, it looks like .484" with a taper.
If I look at a Redding FL 45 Colt sizer die it looks like .478" and straight for the first .4" then .477" for the first .8", and the .467" constriction.

To my crude mind, that means we put a case in a .478" die, it comes out and springs back to .480", and then we put it in a .484" chamber with .004" of clearance and we are all happy.
image above same as link below.

[LAH]

No new 45 Colt cases. I do have the Remington factory loads & for what it's worth here's the measurements.

A-.477
B-.474
C-.474

I've never measured .480 on anything I've tried but then again, I've not measured a new un-fired case.

[44 AMP]

Of course new ammo will measure slightly under the chamber/cartridge specs. They have to go into the chambers, after all! How easy is pushing a .480" case into a .480" chamber going to be? Pretty snug fit, I think. Maybe more than finger pressure alone can manage?

Also, consider all the possible tolerance variations in different guns, over the history of their manufacture. Rem, and everybody else makes their ammo to fit the majority of guns. Some of those guns will be on the small end of the spec range. So, to fit them (and everything else as well) the ammo is going to be a bit undersized, compared to max specs.

[Unclenick]

The SAAMI drawing clearly shows .480" as a maximum OD with a -0.006" tolerance down the length of the cartridge, including where it is over top of the bullet. So that is a finished cartridge maximum dimension, and not a resized dimension. It is clearly a straight wall case.

However, the chamber drawing below the cartridge on SAAMI's drawing shows the chamber has a slight taper, commonly done to assist with ease of loading and extraction. When you fire a case it will press up against the chamber, fire-forming to mirror the taper if the chamber in some degree that depends on the peak pressure, until you resize it. So a fired (but not resized) case will show some taper.

If you wanted to work the brass less, you could get a steel die made to match the chamber contour, I suppose, but the loss of carbide die convenience hardly seems worthwhile. I'd rather buy brass from time to time. If the cases aren't expanding much at the breech because of firing low pressure CAS loads, I would just set the carbide die up high in the press so it sizes only the portion of the brass that grips the bullet.

[LAH]

Well said Unclenick.

[Real Gun]

Posts #10 and 11 need to reconcile their pronouncements. .480 may be a correct interpretation of the spec for "LOADED" ammo, but that is not what real ammo measures.

[Unclenick]

Real Gun,

The SAAMI standards employ a standard engineering drawing practice for critical dimensions called unilateral dimensioning. Where one dimension limit has to be observed in order for the device to function at all, that limit, and not the usual +/- middle value, is the dimension given. Tolerances are then expressed only in the direction away from the limiting value, depending on which direction you can be off and still have the device work.

In the case of cartridges and chambers, there is a maximum cartridge size that will fit in a minimum chamber, and a minimum chamber size that will accommodate a maximum cartridge. Thus, maximum linear dimensions are critical for the cartridge to work in all chambers intended for it, and the minimum linear dimensions are critical for the chamber to work with all cartridges intended for it. The cartridge linear dimensions are therefore expressed as maximum values with a minus tolerance, while the chamber dimensions are expressed as minimum values with a plus tolerance.

In the case of the .45 Colt cartridge, the cylindrical OD is given as 0.480" with a tolerance of -0.006". That means an actual case may be anywhere from 0.474" to 0.480" OD. What number you actually get then depends on the wall thickness of the brass. It varies by brand and sometimes by lot within a brand. For resizing, however, the sizing die designer has a different problem. He doesn't know whose brass you will use, so he has to design the die to resize all brass enough to grip the bullet even when the wall is the minimum thickness. So, sizing dies tend to bring all brass down to the minimum OD.

[LAH]

Well said again.