.45 ACP +P measured in CUP

[KansasTrapper77]

I am looking for published load data for .45 ACP +P with published pressure IN CUP. None of my books or regular websites have it.

I know the pressure max of .45 ACP +P in PSI is 23,000 PSI. I want to know the CUP equivalent. And have it drummed in my head that there is no conversion. So I figure if I can find the same cartridge tested and recorded in CUP I will have an accurate max in CUP units.

Thanks in advance for any assistance or guidance.

 

[GRIZ22]

What are you.trying to do? The 45 ACP doesn’t need a +P for most applications. If you need more power go to a 44 Magnum. There are also other alternatives. 41mag, 45 Colt in a modern revolver

 

[41 Mag]

I just went through a half a day researching +P data. There is data on Hodgdon's site which list CUP, but it isn't standardized for all loads. It also may or may not be with the powder you are using.

That said you can get a ball park idea simply looking down the loads and comparing the velocities withthe pressures. No this isn't on the money but it will give you an idea of about where you'll end up.

 

[AJC1]

Old data doesn't list +p and modern data is in psi. The issue I see most is data listing pressure. I don't see how it matters which system your in as long as your inside limits. You could do the math to calculate the increased pressure based on percentage.

 

[mcb]

You can always go to SAAMI's website and look it up for yourself.

SAAMI Standards - SAAMI

American National Standards Published by SAAMI The SAAMI Standards are published to provide safety, reliability, and interchangeability standards for commercial manufactures of firearms, ammunition, and components. SAAMI Z299.1 – 2018 – Voluntary Industry Performance Standards for Pressure and...

saami.org

The transducer (psi) and crusher(CUP/LUP) are both still valid methods and are both listed for most cartridges in the specs. Unfortunately 45 ACP +P only has the newer transducer (PSI) measurement. There is no SAAMI spec recorded for using the crusher (CUP) method with 45 ACP +P for some reason. Usually due to who every submitted the original 45 ACP +P specs did not do the work and submit it with the rest of the required data when it became a SAAMI cartridge.

Some older less popular cartridges only have a crusher spec and no transducer spec. It's best to always go to SAAMI's website for the most up to date specs.

 

[MEHavey]

Worse engineering (vice scientific) case.
Standard CUP +9.52%

 

[AJC1]

Worse engineering (vice scientific) case.
Standard CUP +9.52%

I'm curious if they just wanted a nice round number for pressure???

 

[mcb]

Also remember older data from around the early 1980's back will often use PSI as the units but in reality they meant CUP/LUP. SAAMI officially added the transducer method in the late 1970's. Before the transducer method came along it was assumed that the crusher method was an accurate measure of chamber pressure. It was not until the transducer method was mature technology in the early to mid 1970's did they realize that the crusher method was not an exact measure of peak pressure and thus we see the introduction of representing crusher measurements with CUP/LUP and transducer with PSI. It would take a few years before the majority of the industry fully adopted the convention of listing crusher as CUP/LUP and transducer at PSI. So check the date of the data you are using and if it was publish in the 1980's or early take all PSI measurements with a grain of salt as they might actually be CUP/LUP. Despite the fact that the crusher method does not give an accurate measurement of PSI it is a very consistent and reliable measurement and thus remained in use today and in the specification but under a new unit.

 

[mcb]

I'm curious if they just wanted a nice round number for pressure???

Most certainly. They round to the nearest thousands in most cases, nearest hundreds in other cases. Some of the specifications and technical guides are only available to actual paying SAAMI member companies and not publicly available. IIRC in some of those documents there are guide lines for when and how to round data and other statistical manipulation of collected data when creating a new cartridge.

 

[KansasTrapper77]

Why? Is a bit convoluted, I have a New Model Blackhawk “Flattop” in .45 Colt. Brian Pearce with Handloader has determined that it is capable of 23,000 psi loads and has published data more than once for “Medium Frame .45 Colts” but even then it is pretty limited. There is an abundance of .45 Colt load data ranging from black powder safe to strong action RUGER ONLY loads BUT most of it is published in CUP.

I am trying to develop a deer hunting load for a 230gr Berry’s Hybrid Hollow Point @ 900 fps. I tried one of the loads published in Handloader but had poor results. I am now searching for other data. I know 23,000 PSI is my max. I would like to find an equivalent in CUP for the piles of already published data.

I’ve searched the handful of books I own, Hodgdon’s website, and even SAAMI’s website as suggested. I figure there is some Data out there of a .45ACP +P in CUP. Just need to find it.

Thanks again all for the replies.

 

[mcb]

Why? Is a bit convoluted, I have a New Model Blackhawk “Flattop” in .45 Colt. Brian Pearce with Handloader has determined that it is capable of 23,000 psi loads and has published data more than once for “Medium Frame .45 Colts” but even then it is pretty limited. There is an abundance of .45 Colt load data ranging from black powder safe to strong action RUGER ONLY loads BUT most of it is published in CUP.

I am trying to develop a deer hunting load for a 230gr Berry’s Hybrid Hollow Point @ 900 fps. I tried one of the loads published in Handloader but had poor results. I am now searching for other data. I know 23,000 PSI is my max. I would like to find an equivalent in CUP for the piles of already published data.

I’ve searched the handful of books I own, Hodgdon’s website, and even SAAMI’s website as suggested. I figure there is some Data out there of a .45ACP +P in CUP. Just need to find it.

Thanks again all for the replies.

Given that SAAMI never published a spec for 45 ACP +P using crusher means your going to have a hard time finding someone that has measure loads using that method since they have no reason to do so since there is no official spec to compare it too.

If you willing to go out on a limb slightly then think about this, as @MEHavey alluded to. We know that the maximum average pressure for 45 ACP +P is ~9.5% greater than 45 ACP as measured with a transducer. That can be calculate from the published SAAMI spec. I believe it is a reasonably safe assumption that we should see a similar increase if we measured those same maximum average pressures using the crusher method. The is no reliable general (across multiple cartridges) conversion between the two measurement systems but when constrained ourselves to one specific cartridge than a 9.5% percent increase in measured transducer pressure we should expect to see very similar percentage increase if we measure using crusher. So 45 ACP has a crusher spec of 18,000 CUP so we would expect 45 ACP +P to measure ~9.5% higher or about 19,700 CUP with the crusher method.

Hope that helps a little. As usual start low and work up to your desired load.

 

[NMexJim]

https://www.hodgdonreloading.com/reloading-data-center

There is a listing for .45 ACP +P and 230 grain HP. There's probably a load in here for you although none are in CUP. Not something I'd worry about personally.

There is a Rainer HP, but I'd probably use the Hornady XTP. You'll have to find your own seating depth just like you would anyway w/ Berry.