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Discussion Starter · #1 ·
See: http://thefiringline.com/forums/showthr ... 008&page=2

There appears to be a conflict of info between what Dean and JohnK are getting from Speer.

Dean has stated that his contact mentioned that .45 GAP pressures of Speer ammo is 19,900 to 21,000(from memory, sorry). JohnK's contact says no, it's up to 23,000 psi. John's contact also stated that Speer does not produce 230 grain loads because they could not accurately measure the actual pressure of 230 grain GAP ammo.
 

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Aw, Rob, that's just Pete… his pulse must be pounding at this point.

[sigh]

I kinda like my information, Pete… with all due respect to JohnK (and I think I know with whom he was speaking at ATK/Speer), the facts are pretty straight forward, even for those of us whose emotional lives are not dominated by all things G.A.P.

Essentially it is this, and it is all based on SAAMI MAP:
  • An ammunition lot that is, on average, 22,800 psi will ship.[/*:fwt4xreo]
  • A lot that is 23,100 psi, however, will not leave the plant.[/*:fwt4xreo]
  • Ammunition that is 21,600 psi is deemed to be "perfect," and that is the specification for which they strive.[/*:fwt4xreo]
Regarding the .45 G.A.P. 230-grain rounds, JohnK's contact is pretty much on the money

There's some fascinating techo-speak explaining exactly why ATK/Speer never pursued one of those heavyweight rounds, and I'm not going to delve into it too deeply only to see it added to your G.A.P. hobbyist's site.

It has to do with the very specific SAAMI guidelines for the placement of the transducer on the sidewall of the cartridge case. What it gets down to is whether one opts for a "robust shellcase" or a 230-grainer, and the ATK folks are very candid about that… at night they sleep the sleep of the Just knowing that there are no kB's with Speer-branded .45 G.A.P. cartridges.

Do not take this to that other thread… let them come here.

I have spoken.
 

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Discussion Starter · #6 ·
The implied question is obvious in the statements. :eek:

Thanks Dean. I appreciate the update. I'll point them to your forum. :)

Ok, ok. I suppose arguing about 21,000 or 23,000 psi is bordering on the fanatical, but inquiring minds wanted to know. :oops:

One more:
Your .45 GAP article (bottom section) states a slightly lower pressure for Speer ammo of 19,900 to 20,500. Is the Speer ideal of 21,600 a more realistic number?
 

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Glen Wertle said:
Internet...What the f*** is the internet?
quote=Holden McNeil in Jay & Silent Bob Strike Back: "The internet is a communications tool used the world over where people can come together to share pornagraphy & bi*ch about movies together."

Fernando Coelho said:
It was about to die off but then Jeff Cooper became the new Glock spokesman... :bolt:
That didn't help the 10mm or the Bren Ten. And the centimeter is a vastly superior cartridge, in my humble opinion of course.
 

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Thanks Dean, I wouldn't argue over whether the max is 22,800 or 23,100 I would assume that 300 psi difference is within the shot to shot variance.

The main point from the other thread was that the 45 GAP is loaded to higher pressures than the 45 ACP to achieve the same external ballistics. Does that basic statement match the information you've been told Dean?

I am interested in your comment about knowing who I spoke with at Speer, if you'd prefer to use PM's or email to discuss it I'd like to hear your thoughts on it.
 

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Discussion Starter · #11 ·
John states:
"The main point from the other thread was that the 45 GAP is loaded to higher pressures than the 45 ACP to achieve the same external ballistics."

The problem I'm having with your comparison of Hodgdon data at the other site is that the ACP rounds were measured in CUP and the GAP rounds were measured in PSI. According to SAAMI standards, here are a few rifle "equivalence" examples to show variance in the two methods of measurement:

222 rem cup: 46,000 psi: 50,000
284 win cup: 54,000 psi: 56,000
30-30 win cup: 38,000 psi: 42,000

And here's a Hodgdon example you pointed to:
200 gr acp with Clays: 17,700 CUP
200 gr gap with Clays: 20,400 PSI

In the earlier days, cup and psi apparently were used interchangebly even though psi was incorrrect since the copper crusher method was used.

Now, there really are labs that can measure psi accurately with a piezoelectric and strain gauge. For example, for years the max pressure for the 270 Win was listed as 52,000 psi (really cup measurement). Then more recently, publications have been showing 65,000 PSI (true psi measurement) for the 270 Win.

So I'm just wondering if the pressure difference you mentioned in referencing Hodgdon data comparing cup-acp and psi-gap is really comparing apples to apples? I further wonder if the pressure difference in the two calibers is significant with factory ammo since so many shooters can't seem to tell the difference when shooting the two calibers.

Another interesting fact about the Hodgdon comparison is that the gap basically matched the acp velocities even though the gap loadings used significantly less powder grains for HS-6, Universal, HP-38, Titegroup, and Clays. That would be quite a savings for reloaders.

just curious, not fanatical. :?
 

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Discussion Starter · #13 ·
John, please don't misunderstand me. I'm just trying to understand the various modes of pressure standards. I don't have an issue that the gap uses a slightly higher pressure to obtain .45 acp velocities. I still find it interesting that the perceived recoil between the two calibers seems similar.

I'm also very intrested in the possibility that heavy GAP loads with 230 grainers may be over-pressure but nobody really knows for sure. And we reloaders may have gone over-pressure at times since we do not have access to a pressure gauge and the pressure signs on the gap case are almost non-existent.

If an when you folks get more info, please let me know. Thanks for the info and ideas. ;)
 

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pete88 said:
I'm also very intrested in the possibility that heavy GAP loads with 230 grainers may be over-pressure but nobody really knows for sure. And we reloaders may have gone over-pressure at times since we do not have access to a pressure gauge and the pressure signs on the gap case are almost non-existent.
CP has said more than once that by the time you see signs of over-pressure, you've been there two or three grains of powder back. Granted, he was speaking of rifle loads and handgun loads would/should be much sooner.
 

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Here is some more data for the 230gr loads in 45 GAP, whether it's usefull in light of what Speer has to say about pressure testing with 230gr bullets remains questionable, it does list the data in PSI like the Hodgdon data.

http://www.winchester.com/marketing/new ... oductid=20

For another datapoint, Alliant doesn't have 45 GAP data (yet) but does list 45 ACP loads with pressure in PSI:

Alliant 45 ACP 230gr FMC data

Still not quite an apples to apples comparision since they're different companies using different components, but it does give us a max range for each caliber in the same measurement (PSI) to compare.
[/url]
 

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Discussion Starter · #16 ·
thanks for the info. :D

Interesting that Winchester believes they have a handle on pressure with 230 grain bullets, ranging between 17,500 to 21,900 psi. Sure hope they're right since the winchester loads seem to have a buffer in there so they are staying below max average pressures of 23,000 psi.
 

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This is freakin' great, with wonderful overtones of Mark Moritz' late "Friendly Fire" column in American Handgunner ten or so years ago! And it's scant wonder than Pete Jordan hasn't puffed this piece anywhere that I've seen… I'm wondering how it escaped his attention.

And if the name "Freburg" strikes a chord with any of the long-timers here, he was one of the savvier posters on the original Sports Play/SSBB when I first logged on in March '94. He was a Moderator on the CompuServe gun board for a time before joining up with FirearmsForum.com.
 

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VERY interesting read.

I haven't had any use for anything Metcalf had to say since a reloading column in American Gun Pimp Shooting Times where he said 5.3 grains of WW231 and a 200 gr bullet gave 950 fps. Having built and fired thousands upon thousands of that very load, I knew that figure to be pure horsecrap. I wrote him a nice letter about it and he never acknowleged this "error" either publicly or privately. It was about that time that I wised up and realized I had better uses for my valuable reading time than Shooting Times, such as X-Men comic books. :)

Later, I would hear several other interesting stories about Mr. Metcalf's veracity and/or integrity. Which I shall not bring up here.
 
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