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Same weight bullet and charge, 2 calibers, same PF?


obsessiveshooter

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If I load for a 45 1911 with the same specs (bullet weight, 4.3 gr titegroup, same primer) as my .40 Limited load, can I expect a similar power factor? I know the speed of barrels can vary, but I'm not sure if other things are at play here. Transferring my powder drop unchanged from the .40 reloading setup would be ideal.  

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I'm sure you will see a difference in velocity due to the difference in case volume between 40 and 45.  I don't know how big a difference, but if I take a 9mm, 124gr JHP bullet and load it with 3.9gr TiteGroup powder, and then vary just the oal from 1.40 down to 1.070, I get different velocities which = different power factors.

 

And, with regard to barrels, if I chrono the same load in an STI Eagle 5.0, a Glock 17, and a Glock 34, I get more than a 5 PF difference between the lowest (Eagle) and highest (Gen3 Glock 34).  What's really interesting, is that I added a Gen5 G34 to the mix, and with the same load, the Gen5 G34 chronos lower than the Gen3 G17.  I wasn't expecting that.

 

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I don't use reloading manuals, I've never owned one and I'm sure I never will.  They are like physical encyclopedias in 2021.  But, I do use Hogdon's website for load data to get started with a new rifle bullet weight or a new pistol caliber.  

The Hogdon website shows that my 4.3gr titegroup under a 180gr will not be close to Major PF.  So case volume clearly plays a big role here.  Also, 4.3gr TG over a 230gr bullet should make PF easily, but not be ridiculously high.   

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20 hours ago, obsessiveshooter said:

If I load for a 45 1911 with the same specs (bullet weight, 4.3 gr titegroup, same primer) as my .40 Limited load, can I expect a similar power factor? I know the speed of barrels can vary, but I'm not sure if other things are at play here. Transferring my powder drop unchanged from the .40 reloading setup would be ideal.  

 

16 minutes ago, obsessiveshooter said:

I don't use reloading manuals, I've never owned one and I'm sure I never will.  They are like physical encyclopedias in 2021.  But, I do use Hogdon's website for load data to get started with a new rifle bullet weight or a new pistol caliber.  

The Hogdon website shows that my 4.3gr titegroup under a 180gr will not be close to Major PF.  So case volume clearly plays a big role here.  Also, 4.3gr TG over a 230gr bullet should make PF easily, but not be ridiculously high.

Almost sounds like somebody asked a question they already had the answer to?

Nice.

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36 minutes ago, Dr. Phil said:

 

Almost sounds like somebody asked a question they already had the answer to?

Nice.

Nope, I just spent some time looking it up this morning.  I started the thread because others might have thought about it too, and because I was hoping to start with other people's real-world experience, especially since USPSA shooter sometimes have work-arounds etc loading for our special needs.   

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Same load in smaller case equals more pressure and more pressure equals higher velocity.  .40 SW case capacity is about 28% less than .45 ACP.  What makes you think the results would be the same?

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