Overpressure potential of substitute bullets in reloading 9mm

[GeoDudeFlorida]

That chart would mean more if it included the same examples for both a "slow" and a "fast" powder for each. Some of the "fast" burning powders suddenly spike when they hit pressure points. The chart you show has some nice neat straight lines. Might be good for "Zip" but don't count on it for all. Also, ambient temperature can change things. I load one big bore cartridge I loaded with 'LilGun. Nice, except in hot weather, suddenly the primers went flat, my ears were ringing (even with good hearing protection), and a few primers pierced. Great load in the winter.

That thing about temperature is interesting. I live Florida. It rarely gets much colder than 30. If it’s colder than that I am not outside shooting. It also rarely gets much over a hundred. Ditto. If it’s over a hundred I’m not outside shooting. So what are the magic numbers for too hot and too cold? I never see a big difference with the powders I use most - Unique, Bullseye, The Dots, 231, 700x, HS6, 2400, 3031, 4064, 3891, LeveRevolution, etc. I don’t travel much but if I do blowing up a gun would ruin the trip.

 

[wst38tx]

Sounds like you know as much about this as these folks your asking. Case capacity does influence pressure and in small cases like 9mm, small differences in case capacity make big differences in pressure. Sticking with bullets of similar profile helps, seating round nose bullets to HP/FP OALs will definitely change pressure more than seating brand X 115 gr RNs to brand Y's 115 RN seating depth. Besides reading primers, one needs to be familiar with their gun. How does recoil feel? How is POI compare to known safe ammo? How far do empties eject as opposed to known safe ammo? Besides using a Chronograph, unless one has pressure testing equipment or sends their ammo in to be tested, it's just a WAG as far as "safe" pressure. Measuring OAL of the bullet itself compared to a known safe(or published recipe) bullet, will tell you what the difference in case capacity will be when OAL is the same.

So true. (exactly my point) And you Sir, know your stuff - you hit it.
And it's not just how far they eject, but at what angle from gun-target line they eject (on a semi-auto). If that case is flinging out in front of you, better check it out. The more clues you learn, the safer you can be.

 

[wst38tx]

That thing about temperature is interesting. I live Florida. It rarely gets much colder than 30. If it’s colder than that I am not outside shooting. It also rarely gets much over a hundred. Ditto. If it’s over a hundred I’m not outside shooting. So what are the magic numbers for too hot and too cold? I never see a big difference with the powders I use most - Unique, Bullseye, The Dots, 231, 700x, HS6, 2400, 3031, 4064, 3891, LeveRevolution, etc. I don’t travel much but if I do blowing up a gun would ruin the trip.

Good point. I saw your mention of Blue Dot. I haven't seen "LilGun mentioned for 9mm, but it has been reported to spike with higher ambient temps, most likely when loaded to full capacity. I use it for "shot putting" 458 SOCOM 500 gr

 

[GeoDudeFlorida]

So true. (exactly my point) And you Sir, know your stuff - you hit it.
And it's not just how far they eject, but at what angle from gun-target line they eject (on a semi-auto). If that case is flinging out in front of you, better check it out. The more clues you learn, the safer you can be.

I went to the indoor range yesterday with some.38 single action revolvers and got pelted with.45ACP cases. I asked the guy with the lane if it was normal for his Dan Wesson to toss cases that way. It wasn’t. He was grateful for the mention. New load he thought was great but a little hot. Turns out it was way hot.

 

[FROGO207]

My take on the OP's question is that the internal volume of a finished round affects the pressure. This is why the FMJ and JHP of the same weight have diffetent charges. The JHP will be longer. The total length and therefore insertion depth will be different. Coupled with a smaller total case volume than say, 45 ACP smaller changes cause larger pressure swing. Still if you work up a load within published data for that style and weight bullet you should be well within your safe range. I worry more about good neck tension and bullet setback in 9MM than the charge going nuclear if I make them a bit heavy for the published data.

 

[wst38tx]

No.

You can't buy bullets that don't vary by a few thousandths or more in OAL and base-to-ogive, even premium BTHP rifle bullets. Your run of the mill pistol bullets will have even more variation, and that's perfectly fine because it doesn't matter.

Seating depth and bullet profile does effect pressure, but it's not nearly as sensitive as you've assumed.

You should demonstrate this for yourself be testing. Pick a bullet, determine plunk COAL, and workup loads at plunk and plunk minus 0.030. You will find a small difference at most.


Some does, some doesn't.

Maybe I'm being "too careful?" But then, I'm in new territory and I don't have to do this. I'm retired, have plenty of time, it's a challenge, and my acceptable risk quotient is low. Thank you for your input.

 

[wst38tx]

Here is an eye opener for you. Cruise on over to Western Powders website and open the reloading data fire. Then scroll down to the 9mm and pick a powder, or all the powders and compare data for a 115 or 124gr bullet. Then pay attention to how much the charge weight varies between bullets of the same weight. It may open your eyes.

Very good loading manual, they do a great job. That is enough to make me switch to their powder line. That and I've heard good things about their powders.

 

[fxvr5]

This is why the FMJ and JHP of the same weight have diffetent charges. The JHP will be longer.

With 9mm bullets, the FMJ bullets (typical RN) are generally longer than JHP bullets of the same weight from the same manufacturer.

 

[kmw1954]

Very good loading manual, they do a great job. That is enough to make me switch to their powder line. That and I've heard good things about their powders.

It was enough to make me switch when I started loading plated bullets. As you can clearly see not all plated bullets of the same weight are using the same powder charge. My be close but they are different.

I have switched to AA#2 and Silhouette for my pistols and have started using TAC for my 223.

 

[lordpaxman]

The challenge is when you can't find published OAL length for the bullet you are substituting.

I’ll put a plug in here for good notes, whether that’s hard copy, soft copy or both. I measure bullet OAL of all my projectiles and keep records of them. When comparing to published data, if I can, I’ve obtained either the bullet or factory ammo and measured that. Even knowing that there will be differences in the bullet technology. I try to find multiple sources of published data for an approximate fit, even then there may be a best guess involved. Even if you use the exact same components of published data, chances are likely it won’t perform the same in your firearm. Start low, but not too low and work up.
You need to be cognizant of both the low and the high side. Good luck.

 

[fxvr5]

That chart would mean more if it included the same examples for both a "slow" and a "fast" powder for each. Some of the "fast" burning powders suddenly spike when they hit pressure points. The chart you show has some nice neat straight lines. Might be good for "Zip" but don't count on it for all.

Which powders do the 'spike' thing, and where can I see the pressure plots (in handguns) that demonstrate this? Can you point me towards other handgun pressure plots that show a non-linear pressure changes? Thanks.

 

[NMexJim]

I wouldn't avoid any decent mass-manufactured bullet, especially in these times.

Understanding upfront that there is really no standard for bullet manufacture will get you off on the right foot. You can buy bullets that won't have a specified COL available (flat nose being t

I’ll put a plug in here for good notes, whether that’s hard copy, soft copy or both. I measure bullet OAL of all my projectiles and keep records of them. When comparing to published data, if I can, I’ve obtained either the bullet or factory ammo and measured that. Even knowing that there will be differences in the bullet technology. I try to find multiple sources of published data for an approximate fit, even then there may be a best guess involved. Even if you use the exact same components of published data, chances are likely it won’t perform the same in your firearm. Start low, but not too low and work up.
You need to be cognizant of both the low and the high side. Good luck.

An illustration that might help the thread:

 

[9mmepiphany]

The challenge is when you can't find published OAL length for the bullet you are substituting.

I measure actual bullets. I usually have a left over bullet from any purchase that I can use for comparison to the new bullet I'm planning on loading

 

[Walkalong]

One reason I log the length of all bullets I use in my Excel load data file. Comes in handy to know.