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Discussion Starter #1
I've got multiple loading manuals, including Speer, Hodgdon, Hornady, Sierra, and Lyman, Nosler, Barnes, etc.

Also, I've ck'd. several (maybe not ALL ???) on-line sources, and I've only found one listing for +P 45-ACP, which was on Alliant's website.

So, I've got +P data for only one Powder, Allian't Power Pistol. Those loads seem OK, but I would like to try other powders in +P loads.

Can anyone point me toward sources for additional +P load data ?

Thanks --CC
 

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Everything I've read about +P says that it is a "factory only" round.

+P cases have a smaller internal volume than standard cases. A max "non +P charge" in a +P case can result in dangerous pressures.

The "factories" get away with this because they load +P rounds with the SAME LOT OF POWDER that has exceptionally consistent burning rates. As a consumer, you can't be assured of that consistency and you are taking an awful chance if you load anywhere near max in +P cases.

I have found +P cases to be useful for reduced loads, target stuff, where I am looking for small groups rather than lots of power. The smaller case volume raises the pressure enough to make the small quantities of powder burn more consistently.

Regards and don't blow up,
Bob Hunt
 

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+P pressure for .45acp is 23Kpsi. You can hit that with 10.8gr of AA#5 pushing a 185gr JHP, which will yield a velocity (Hornady XTP) of 1150fps, out of 5" barrel on a cold day.

But I will make a couple of suggestions:

(1) +P loadings really don't do much for you - they are hard to shoot (recoil) and they beat on your gun. 10.2gr of AA#5 pushing the same bullet will give you 1050fps and stay within 21Kpsi. Having played with it, I don't think the 100fps is worth it.

(2) If you screw up, because you didn't believe 10.8gr is an absolute max, or you messed up reloading, or your pistol can't handle it - and things go KABOOM. I'll sign the get well card they attach to the wet/dry vac they used to transport you to the hospital.


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Have a great day!
 

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Discussion Starter #4
Really interesting feed-back...

I'm new to loading and shooting the .45-ACP, so I'm admitting I'm no expert ! AND I DERN-SURE DON'T WANT TO BLOW MY GUN APART !!!

So I am actually seeking information and advice here (I'm NOT trying to incite any internet riots, start any arguments or flame-wars, etc. )

My only semi-auto pistol '+P-pressure' reference point is loading and shooting high-intensity cartridges (.40-S&W & 10mm) in Glocks, which are known to have 'generous' chamber dimensions. I've NOT experienced the bulged cases that so many folks have commented on regarding brass ejected from a typical Glock chamber... And my early experiments shooting +P loads in my 1911 shows no bulged cases. (fewer than 200 rounds of +P, so maybe not a valid sample ?)

I've heard +P 38-Special loads may be UN-SAFE in some (older / weaker) revolvers, and I've also heard that +P .38-Special loads should only be used on a limited basis in several better-quality revolvers (to avoid early frame fatigue, etc.)

But in this case, the firearm manufacturer has said that their firearm is designed to handle consistent of use of +P ammo. (I'm shooting a Springfield TRP -- and SA has told me that this model is designed to safely handle a steady diet of +P loads).

Maybe the reasonable answer is to keep the 45-ACP loads on the more-accurate and milder-side ???

STILL, I remain very curious as to why it is considered SAFE to load .40-S&W rounds to a pressure of 33,000-CUP while the 45-ACP must be keep below 20,000 CUP in firearms of the same basic design ???

I don't expect my 1911 to become a .45-magnum, but if I can SAFELY load +P 45-ACP to pressure levels similar to other semi-auto calibers, and if the recoil doesn't preclude reasonable accuracy, then... WHY NOT ?

I'm thinking that the primary issues are to keep the +P loads SAFE by sticking with PUBLISHED LOADS. (Thinking that a published load has some margin of safety regarding randomness of powder charges and powder variations from lot-to-lot ???)

I've fired fewer than 500-rounds in a 1911, so I'm seriously seeking input from those of you who have been working with the 45-ACP and the 1911 design for several years (vs. my broad experience which now spans 'several days'
)

Also, I really don't want to get several hundred rounds of +P ammo loaded and have to dis-assemble it all.

Thanks --CC
 

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1. You do not get a whole lot from +P, which in most calibers is loaded to 10% higher pressure than standard. According to the rule of thumb developed by Homer Powley and refined by VihtaVouri, a 10% increase in pressure will come from a 5% increase in powder charge - that's .2 to .5 grain for most .45 powders - and will give a 4% increase in velocity. Not much return.

2. A .45ACP, even +P is loaded to lower pressure than .40, etc. because the load on the gun's lockup is force = pressure x casehead area. At the same pressure, a .45 would be carrying 29% more force against the breech than a .40. Proof loads are about 1/3 overloads, so you would be well into the safety margin of the gun. Which you can do with good brass, good barrels, and acceptance of a shorter service life. My FLG has a gallery of battered slides and cracked barrels to show it.

3. The .40 is not loaded to 33,000 CUP all that safely. For pictures of a G35 kaBoomed with factory loads, see: http://www.pistolsmith.com/viewtopic.php?topic=5241&forum=14&10

4. I think .38 Spl +P is a bit of an exception. Raising blackpowder ballistics by 10% is not going to blow up a modern gun. It might batter a small framed gun, but they don't usually get shot a lot. In a K frame .38+P is about my comfort limit for match shooting.
 

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Remington sells +p Nickel .45 Brass, for those who wish to tread where angels fear to go!

At least put on Hogue rubber grips so if the case blows out, the hot gas won't send splinters of wood into your hand !
 

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Discussion Starter #7
I really appreciate the feedback and comments from each you that have responded to my original post about +P 45-ACP load data.

What has been most revealing (EYE OPENING) for me was this information posted by Jim Watson:

-- "The .40 is not loaded to 33,000 CUP all that safely. ( http://www.pistolsmith.com/viewtopic.php?topic=5241&forum=14&10 ) Those pictures were (& still are) MOST ENLIGHTENING.

It appears the 'safety margin' of these high-pressure loads is much more narrow than I ever previously imagined.

Also, the physics of back-thrust or force applied against the breach-bolt increasing as case diameter increases seems to be scientifically reasonable.

I remember from my Physics and Fluid Powder training (which is now rather 'dusty' from years of non-use) that in a "pressure vessel" (gas-cylinder, or propane tank, etc.) that pressure forces are equal on all surfaces, in all directions; however, I also know that "Pressure X Area = Force" and that as the diameter of a cartridge case is increased, so is that resulting Force.

It has been years since I've even thought about the physics of pressure, force, etc. let alone applied it to internal ballistics.

Thanks to your combined comments (and those DERN pictures) I've suddenly developed a MORE CONSERVATIVE ATTITUDE about my load selection for 45-ACP and especially the .40-S&W.

Again, thanks to all of you for the input. --CC
 
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