.45 Colt (non-Ruger Blackhawk) pressures?

[jager]

   I was researching some new loads for my Colt "clone" and ran across an article by "Chuck Hawks" that mentioned about .45 Colt SAMMI loading pressure was 14,000PSI or 15,900CUP! (You might note, that Hawks is not a fan of "high pressure" .45 Colt loads in any brand pistol!) He stated this information as a matter of "fact" - end of discussion.
   I'd always read that the 14,000 was the maximum "pressure" and assumed that it to be the same as PSI in this cartridge because most reloading manuals seem to treat them as being interchangeable. Some manuals, like Accurate, state that SAMMI specs are 14,000CUP while others say 14,000PSI. The NRA's book, "Handloading", states SAMMI specs as 14,000CUP but show acceptable "Colt" loads as  <15,900CUP.
    Does anyone know for certain, or has the pressure for this cartridge been repeated so many times that it was just a "carry over" from the "black powder" days of "calculating" pressure?
   While 1,900CUP is not "earth shattering", it could account for the difference in the .5 to 1gr. of powder allocated by one "source" over another with the attenuating 50fps increase in velocity. (At least "smokless" powder would have "parity" with the old "40gr black powder load of 1873 without "fudging" .)  BTW, most of my loads are 720fps "cowboy" loads just for the "fun of it" .

[Graybeard]

PSI and CUP are seldom the same. The .45-70 is one round I can think of off the top of my head where it is. I don't think the .45 Colt is however. I'm with Chuck on this one tho most often am not in agreement with him. At least as far as the Colt guns and clones are concerned ya really shouldn't be trying to hotrod the old warhorse.

Now in a Ruger or TC it can be pushed hard. Just make darn sure you never let one of those rounds get mixed up with Colt or Colt clone loads. That's likely why he doesn't like doing it. If you own both I'd not recommend hotrodding it.

[Racer X]

If you have clones and Blackhawks, definitely be careful about intermingling hotter loads. I used to have a H&R Shikari in 45/70 that was to be used only with Trapdoor-level loads. When I bought a Marlin Guide Gun in 45/70 that can handle much hotter loads, I sold the H&R to avoid the risk.

Regarding Chuck Hawk's article on the 45 Colt, I read it and I generally disagree with all his assertions.

1) 45 Colt brass is not weaker than 44 Mag brass. The reason for better case life in 44 Mags is because factory 45 Colt chambers are grossly oversize, which leads to earlier case failure. Dick Casull developed the 454 using standard solid case head designed 45 Colt brass. In tight chambered custom 5 shot cylinders, builders like Bowen and Clements run 45 Colt ammo at 55,000 PSI, which eclipses even +P 44 Mag ammo. And they run these pressures using standard 45 Colt brass. Hamilton Bowen's book does an excellent job refuting all the "weak case" myths. For example, he writes where he sectioned and measured 44 Mag and 45 Colt brass thickness and noted both calibers are "within production tolerances", meaning essentially no difference. In fact, some 45 Colt brass is even thicker than 44 Mag brass he measured.  

2) Although the reloading manuals for heavy 45 Colt loads state "for use with Blackhawks/Contenders", how Hawks accurately say that a Redhawk cannot be loaded to the same "Ruger/TC Only" levels stated in the manual? Redhawk 45s have much more steel between the cylinders and could likely be loaded even hotter than Blackhawks, (although I would not venture there without published, tested load data from a reputable bullet or powder manufacturer).

3) Reference Speer Manual # 13 reloading data for the 300 grain JSP bullet for both the 44 Mag and 45 Colt. Same bullet design, profile and construction. At max loading using H110 and 296, both calibers are running ~ 1200 FPS. However, the 44 Mag load data for that bullet states a max operating pressure of 40,000 PSI; the 300 grain JSP 45 Colt max pressure is only 25,000 PSI. That is, the 45 Colt pushes a larger diameter bullet of equal weight, profile and construction the same velocity, with 60% less chamber pressure.

4) Hawk's quote "The Ruger Super Blackhawk .44 Magnum is the top of the line and a little bit nicer gun than a standard Blackhawk, anyway" - Other than aluminum grip frames and ejector rod housing (blue models only), what proof does he have that standard Blackhawks are not built to the same quality standards as Super Blackhawks?

[44 Man]

If you have a Colt or clone, you really, REALLY need the book 'Loading the Single Action Army' by Dave Scoville.  It's available from Wolff  publishing, the same people that publish the fine 'Rifle' and 'Handloader' magazines.  It should be required reading for anyone loading for a 'non Ruger' single action.  He has a wealth of information in there and is facinating reading.  As for cup and psi, no they are not the same, but there's not a lot to worry about when loading for the .45.  All manuals list the 'normal' loads giving you about 850 fps with 250 gr bullets.  As Dave points out in his book, the Single Action is also chambered for the .45 acp with no distiction made between standard and +P loads.  +P in the acp go to 19,000 psi.  Dave has probably fired more rounds through the old Colt than all of us here combined (well, maybe except Lloyd).  He says it can safely be loaded to 900/950 fps.  A 250/255 gr SWC or WFN cast bullet at 900 fps is a serious round that can take most anything that most of us care to shoot, excepting the big bears.  One of the loads listed (it is listed as max in a SAA gun though) is with the newer RCBS 270 gr SWC made for the SAA, over 20 gr of H4227.  That load did 925 fps through an old Dakota 4 3/4" barrel I used to have.  Remember (oh, this will start an argument) that 'momentum' trumps 'velocity' in heavy handguns.  Velocity allows us to shoot near point of aim at longer distances, but with heavy (250 gr and up) handgun bullets, momentum is what drives deep and kills all out of proportion to the .45's paper ballistics.  A good illistration of this is the old British .455 webley.  Pushing a 255 gr bullet to only 700/750 fps, this round was considered an excellent 'manstopper' back in it's day and served the Crown through several wars.  I recommend Dave Scoville's book to any handloader or enthusiest of the SAA and clones, you will never regret you bought it!  44 Man

[jager]

   Thanks for all your replies. I got rid of my Marlin 1894CB and Ruger Blackhawk a couple years ago to preclude mixing up my higher (non SAMMI loads). I concluded long ago that if I wanted to go the "magnum" route I'd buy a .454 or .44RemMag that have "established" SAMMI maximum standards.  I'm not interested in "hotrodding" the "clone", but I am interested in establishing what the "true" SAMMI specs of the .45 Colt is. And, I do load for a 1917 Webley .455 (not a converted .45ACP) that I would never convert to the higher pressure cartridge due to the design and age of the pistol.
    The question of whether 14,000PSI, 14,000CUP, or 15,900CUP is the actual maximum pressure for a cartridge that is 137 years old? Was this pressure "interpolated" from "black powder" data, or was it pressure tested after it was first loaded with "smokeless powder?" If the 14,000PSI is the "criteria" and it is not the same as CUP, why do some reloading manuals use 14,000CUP as their "stated" maximum?  I want to know because if it is based on black powder data that has an entirely different pressure "gradient", it is not an accurate measure of pressure for smokeless powder in the same cartridge.  We know case strength and dimensions have changed over this time period, along with newer guns.  Was the old data based solely on a "balloon head" cartridge with black powder, which delivered higher velocities than the newer more efficient powder? The resulting answer may be that CUP is a more accurate representation of pressure in this cartridge than PSI if it was based on black powder pressure data from the outset.
   44man, I have not read Scoville's book, but have taken "Handloader" magazine that he edits for years. He can be a good read and I will check it out, thanks!

[dpe.ahoy]

Just think of it as the temperature readings in C and F.  It's the same temp. just using a different scale.  DP