How to determine pressure for handloads?

[FoghornLeghorn]

Some manuals give pressures of various loads. For the 45 Colt in the 1873 Winchester max pressure is 14,000 psi.

But there are no such guidelines for Vihtavuori powders, and I'm wanting to use their N340 powder for 45 Colt 200 grain plated. (BTW, Midway just got a bunch of Vihtavuori powders in stock.)

Their starting load for the 200 grain lead bullet is 10.9 grains for 1119 fps. Max load is 11.6 grains for 1194 fps.

I'm curious because they have a whole different category for cowboy shooting and don't even list the N340 powder. They list the N330 powder 8.0 grains at 876 fps. Max for N330 is 8.6 grains at 978 fps.

Is that because of the parameters for cowboy action shoots? Or is it because the 1873 action and the Colt SAA is too fragile for anything more?

BTW, both Berrys and Xtreme say their standard plated bullets are fine for any velocity up to 1200 fps.

[ballardw]

Most of the cowboy action types are looking for just enough oomph to get to the target. Minimum recoil translating to faster recovery and follow-up shots.
Plus minimum powder cuts costs for those that do lots of practices.

If you have $$$ then perhaps https://www.shootingsoftware.com/pressure.htm though I'm not sure how well that translates to revolvers.

[HiBC]

I suggest you look over and understand the togglelink breech lockup used in your 1873 Win clone,and compare it to the locking bars of later Winchesters like the 92. They are not in the same league for strength.
There is reason to heed the 14k psi figure,and IMO,equally good reason to NOT go out on thin ice making guesses. I'd stick to pressure tested,published data.

Published Cowboy loads are likely of appropriate pressure for the toggle actions.

I'll agree you don't need to worry about the velocity limitations of the cast bullets.I would not chase those velocities.

You might look at handgun data appropriate to older original Colt 1873 guns.

For perspective,the1911 Colt semi-auto pistol was intended to roughly equal the 45 Colt SAA performance. Around 800 fps. The 1911 operates at a pressure of about 18,000 and I'm not sure what pressure unit, whether LUP,CUP,or PSI.

Respecting your 14 k, I'm not looking it up,but it would surprise me if you can safely go into the "over 1000 fps" realm. The Cowboy loads might be a good idea.

[MarkCO]

Max pressures are determined by SAAMI. The labs of the manufacturer's use various (hardly ever actual copper or lead crush pellets) measurement apparatus to evaluate their powders/bullets/primers, with variations, in pressure barrels, usually fitted with transducers. As max pressure is approached and data is collected, the ballistician determines the high end, with a factor of safety for a certain recipe. Some extrapolation occurs along with experience at the lower end, with some spot checks of course. Usually, slower (relatively) powders are not listed for pistol loads when the pressure won't seal the case to the chamber suitably or the combustion becomes inefficient (dirty).

A very rough explanation of how some labs develop their load data. I have spent some time in several over the years, just absorbing what they are doing and how. Discussions when they are done are a bonus.

[USSR]

Actually, since FL is talking about Vihta Vuori powders, SAAMI is not involved, but rather Europe's CIP. However, I'm sure they are well aware of the long established 14k psi limit for the .45 Colt. As previously stated, cowboy loads are loaded low to reduce recoil, and the Winchester Model 1873 is weak by design, so loads must be light.

Don

[P Flados]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

I ran Quickload for a 200 Lee RF.

I would tend to stay well below the calculated maximum pressure. Quickload is not know for accuracy with pressure in straight wall ammo.

Cartridge          : .45 Colt (SAAMI)
Bullet             : .452, 200, LEE 452-200-RF
Useable Case Capaci: 32.749 grain H2O = 2.126 cm³
Cartridge O.A.L. L6: 1.580 inch = 40.13 mm
Barrel Length      : 20.0 inch = 508.0 mm
Powder             : Vihtavuori N340

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.222% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-22.2   35     7.00   1089     527    7370    699     98.2    2.251
-20.0   36     7.20   1112     549    7740    718     98.6    2.201
-17.8   37     7.40   1134     571    8122    736     99.0    2.154
-15.6   38     7.60   1156     593    8516    753     99.3    2.109
-13.3   39     7.80   1177     615    8921    770     99.6    2.066
-11.1   40     8.00   1198     638    9339    786     99.8    2.025
-08.9   41     8.20   1219     660    9768    801     99.9    1.986
-06.7   42     8.40   1239     682   10209    815    100.0    1.948
-04.4   43     8.60   1259     704   10663    829    100.0    1.912
-02.2   44     8.80   1279     726   11129    842    100.0    1.878
+00.0   45     9.00   1298     748   11606    856    100.0    1.844
+02.2   46     9.20   1317     770   12097    869    100.0    1.812  ! Near Maximum !
+04.4   47     9.40   1336     792   12600    882    100.0    1.780  ! Near Maximum !
+06.7   48     9.60   1354     814   13115    896    100.0    1.749  ! Near Maximum !
+08.9   49     9.80   1372     836   13643    909    100.0    1.719  !DANGEROUS LOAD-DO NOT USE!
+11.1   50    10.00   1390     858   14184    922    100.0    1.691  !DANGEROUS LOAD-DO NOT USE!

[FoghornLeghorn]

Originally Posted by P Flados

I ran Quickload for a 200 Lee RF.

I would tend to stay well below the calculated maximum pressure. Quickload is not know for accuracy with pressure in straight wall ammo.

Cartridge          : .45 Colt (SAAMI)
Bullet             : .452, 200, LEE 452-200-RF
Useable Case Capaci: 32.749 grain H2O = 2.126 cm³
Cartridge O.A.L. L6: 1.580 inch = 40.13 mm
Barrel Length      : 20.0 inch = 508.0 mm
Powder             : Vihtavuori N340

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.222% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-22.2   35     7.00   1089     527    7370    699     98.2    2.251
-20.0   36     7.20   1112     549    7740    718     98.6    2.201
-17.8   37     7.40   1134     571    8122    736     99.0    2.154
-15.6   38     7.60   1156     593    8516    753     99.3    2.109
-13.3   39     7.80   1177     615    8921    770     99.6    2.066
-11.1   40     8.00   1198     638    9339    786     99.8    2.025
-08.9   41     8.20   1219     660    9768    801     99.9    1.986
-06.7   42     8.40   1239     682   10209    815    100.0    1.948
-04.4   43     8.60   1259     704   10663    829    100.0    1.912
-02.2   44     8.80   1279     726   11129    842    100.0    1.878
+00.0   45     9.00   1298     748   11606    856    100.0    1.844
+02.2   46     9.20   1317     770   12097    869    100.0    1.812  ! Near Maximum !
+04.4   47     9.40   1336     792   12600    882    100.0    1.780  ! Near Maximum !
+06.7   48     9.60   1354     814   13115    896    100.0    1.749  ! Near Maximum !
+08.9   49     9.80   1372     836   13643    909    100.0    1.719  !DANGEROUS LOAD-DO NOT USE!
+11.1   50    10.00   1390     858   14184    922    100.0    1.691  !DANGEROUS LOAD-DO NOT USE!

Thank you, sir, for that.

[Unclenick]

Please note that QuickLOAD is an estimator and its pressure calculations cannot be considered equivalent to actual testing. If you look at data from it and from commercial measured pressures for the same load you can get mismatches for a number of reasons, so its estimates need to be vetted. Usually, QL's starting loads are fine (10% below max charge weight) but just as with published data, you need to work up loads while watching for pressure signs. It does not take into account problems with case fill, for example, so take it with a grain of salt. I love the program and have used it for about twenty years now, but know to watch out for its limitations.

The reason N340 is not part of the published data is likely because it is slower burning than the powders you found data for, and slower burning powders generally require more pressure to burn cleanly and completely and to produce consistent velocity than faster powders do. They also tend to need larger charges. I expect the manufacturer found it unsatisfactory for this purpose, though you can try it. Just be sure to start low and watch for the usual pressure signs.

[pete2]

Best us poor folks can do is stay within published data limits. I had some starting loads from an old Speer book that were hotter than they should have been so be careful.

[zeke]

From V V 6th edition (1996?) Reloading Guide
Hdy 200 lswc, WLP primer, 1.594 col, Rem brass, 6 in barrel, CIP standards, N340

10.4 gns = 1080 fps, 10,000 psi (starting)
11.2 gns = 1156 fps, 13,300 psi (max)

If memory serves, V V eventually using our psi measuring standards and reduced some of their hotter pistol loads, which these do not appear to be (hotter).

[Unclenick]

QL slightly overestimating pressure in this case.

Zeke,

I have a copy of that manual and didn't think to look. Should have. Its pressures are all "psi by copper crusher", same as the old military tech manuals. You can see this by looking at the CIP's current peak pressures vs. the ones in that manual. It puts the 30-06 at 350 MPa, for example, but the current CIP number is 405 MPa.

Fortunately, in the case of the lower pressure revolver cartridges, the copper crusher and the piezo transducer tend to agree pretty closely, so there's no change here. The SAAMI CUP and psi for 45 Colt are the same and the CIP numbers, which come out just short of 16,000 psi also stayed the same (110 MPa or 1100 Bar). The fact this number is a little higher than SAAMI is due to differences in the diameters and locations of the pressure sampling ports and different inertial mass in the pistons.

[zeke]

This manual has 2 sections of 45 LC. One measured in CIP, one by CUP. Am not sure how this correlates, but the manual specifically states the CIP is done by European Standards at the case mouth, and not by SAAMI standards.

If memory serves, V V later started using SAAMI standards.

All kind of irrelevant for the OP purposes, and am certainly not very knowledgeable on pressure testing methods.

[Ike Clanton]

Why do so many max 45 colt loads stop at 13,300 PSI when 14,000 is the max? The listed CFE-P max load is 9.2 grains at 13,300 PSI so I pushed it up to 9.5 which in theory should put it around 14,000 and have had no issues.

[Unclenick]

Ike,

That's a safety measure used in most load manual data. It means that during testing the load developer had enough variation that one or more rounds made it to 14,000 psi when the average was 13,300 psi.


Zeke,

I checked and what I have is VV#2, from 1995. It's got CIP pressures by copper crusher. VV#3 was published in 2002. VV#4 was published 2007. I can't find a hardbound #6, so I am wondering if you remember the version incorrectly. #2 does not break 45 Colt into standard and CAS loads, but the abbreviated PDF manual published in 2004 does (it has no edition number) so your version must be late enough to do that, since you say there are two 45 Colt sections.

Both CIP and SAAMI used copper crushers first, then piezoelectric transducers later. The CIP crusher and piezotransducer are not the same, dimensionally, as SAAMI style copper crushers and conformal piezo transducers, so they just don't convert all that well.

The CIP method does not measure at the case mouth. It is the NATO EBPAT method that does that. The CIP method measures 45 Colt pressure 12.5 mm (about half an inch) from the head of the case (letter M column on the CIP homologation table). SAAMI measures it at about 16.2 mm from the head.

Vihtavuori will have to use the CIP method in Europe, as it has the force of regulatory law there, while SAAMI is a voluntary industry standard here. If you look at the VV data, the barrel lengths are all in mm, so you know they are European test barrels and not US standard. I know SAAMI and the CIP have held discussions about how to reconcile their measuring systems, but haven't got all that far yet.

[ballardw]

Originally Posted by Unclenick

Ike,
I know SAAMI and the CIP have held discussions about how to reconcile their measuring systems, but haven't got all that far yet.

I can see it now: SCAAMPI as a new standard/organization!
And don't call them shrimps!

[zeke]

Uncle Nick-Am referencing the the paperback Reloading Guide 6th Edition. On the back cover it indicates SIXTH EDITION, 1996

In addition to the information given abpve earlier on page 9 in the disclaimer, there is also a warning before the actual handgun data.

" The loading data in the metric tables given here were obtained in laboratory conditions based on CIP October 1, 1992 pressure limits and respectively in the English tables on Saami March 9, 1993 pressure limits. In the both above mentioned tables the pressure values are based on the pressure measurement according to the CIP. Although the test methods according to CIP and Saami are similar, no known correlation exists between these two accepted methods of pressure measurement."

V V put out a series of free bee paperback RELOADING GUIDES. The earliest owned is 2nd edition, but can't find a date on it.

[HiBC]

I don't have any toggle link lever actions. I don't have experience with them.
14,000 (cup,lup,psi cip,or whatever unit) seems prudent.

Reference was made to "pressure signs"

Aside from maybe difficulty cycling the lever, what "pressure signs" will there be to read at 14k?

The term "pressure signs" makes me think of the voodoo of reading brass,primers,etc that occur on the high side of 60,000 psi.

When I load for my 120 year old single locking lug Krag I just do not think of "pressure signs" as my boundary.

I just bought a Lyman 311284 30 cal mold that supposedly was designed for the Krag. Its 214 gr. From a mag article on loading for the Krag,its supposed to be accurate to about 1900 fps.

I'll be well short of the 40k range a Krag is supposed to be good for, and I'm not thinking in terms of "pressure signs" ,or a lack of them, suggesting I can "stoke her up a couple more grains"

I'm thinking with the gun designs less robust than a 98 Mauser standard,the "pressure sign" I might read is the bolt in my eye socket.

I prefer more margin of safety than that. Published,tested data is a good thing.

[T. O'Heir]

Vihtavuori powders use CIP Specs. Slightly higher than SAAMI, but still well within safe margins. Rummage around here.
https://www.cip-bobp.org/en/tdcc
Seems to me there's a pressure formula in the Lyman book. Likely make your head explode though. It's Math. Serious Math.

[Unclenick]

Zeke,

Got it! They must have put out the same abbreviated data booklets that Hodgdon and Winchester and others did before the Internet became ubiquitous. I don't have any of those. But you said it has two areas for 45 Colt. Is one standard and one CAS? My 1995 hardbound book doesn't have that, but if your's does, that's pretty strong proof that 1996 is when they first started the second classification.