9mm- max pressure and seating depth

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9mm- max pressure and seating depth

Post by Jarhead » 30 Jan 2021, 3:41 pm

Hey all,

I fired some handloads out of my 92X today and got some mild pressure signs......

I am running 9mm Luger:

COAL of 1.1.65
3.2 grains APS450
Susan island 124 grn LRN coated
Win small pistol primer

IMG_3134.JPG
IMG_3134.JPG (343.21 KiB) Viewed 1847 times


I have backed off the load a bit as a result to 2.9 grns

The range officer asked me what seating depth I am running- I told him 1.165. He said it is too long and if I make it closer to 1.1, the pressure problem will go away. I am reluctant to do this. A longer seating depth means more volume to me and less peak pressure. I said so. He mentioned that more case volume means more space around the power so a faster burn. That makes sense too. If the powder is tightly packed, it can burn slower and result in a lower peak pressure.

I am not gonna risk damage to my shiny new 92X Performance (which I picked up just this morning- Yayyy!!!) by experimenting with this to reduce my pressures signs but I thought I would ask the brains trust on this forum what their experience is..........

So- three questions:

1.What does a shorter COAL do to peak pressure?

2. Does anyone have load data for 124 grn Susan Island LRN's?
Regards,

Jarhead
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Re: 9mm- max pressure and seating depth

Post by bladeracer » 30 Jan 2021, 5:15 pm

I can't see any pressure signs on that case - what makes you suspect pressure?
Does factory ammo look any different?
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Re: 9mm- max pressure and seating depth

Post by yoshie » 30 Jan 2021, 7:05 pm

I load mine to 1.125, I'm still using AP70 so I can't comment on the load.
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Re: 9mm- max pressure and seating depth

Post by Jarhead » 30 Jan 2021, 8:04 pm

bladeracer wrote:I can't see any pressure signs on that case - what makes you suspect pressure?
Does factory ammo look any different?


Now that you mention it Bladeracer, I think you are right. The primers look somewhat flat around the middle but when I look at fired factory Winchester loads, the primer look a lot flatter!
Regards,

Jarhead
___________________________________
Beretta 680 Special Skeet 12G (1350 fps)
Savage MkII .22 (1040 fps)
1969 Mustang Fastback (227 fps)
Tikka T3 6.5 CM (2660 fps)

The Mustang looks the fastest but it's not.
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Re: 9mm- max pressure and seating depth

Post by Jarhead » 30 Jan 2021, 8:06 pm

LOL, my third question did make the cut......


3. Am I right in thinking a 1/2 flattened primer is a significant pressure problem.
Regards,

Jarhead
___________________________________
Beretta 680 Special Skeet 12G (1350 fps)
Savage MkII .22 (1040 fps)
1969 Mustang Fastback (227 fps)
Tikka T3 6.5 CM (2660 fps)

The Mustang looks the fastest but it's not.
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Jarhead
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Posts: 188
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Re: 9mm- max pressure and seating depth

Post by bladeracer » 30 Jan 2021, 10:07 pm

Jarhead wrote:LOL, my third question did make the cut......


3. Am I right in thinking a 1/2 flattened primer is a significant pressure problem.


Probably not, primers vary so are a very poor indicator of pressures.
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Re: 9mm- max pressure and seating depth

Post by wanneroo » 31 Jan 2021, 10:08 am

1.165 OAL seems excessively long to me.
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Re: 9mm- max pressure and seating depth

Post by Macross » 04 Feb 2021, 7:22 am

You can run up to 4.0gr of APS450 behind a 124gr bullet no worries.... Your load sounds very light to me. I have to load 4.0gr to get my glock 34 to cycle properly. Anything lower and it will stove pipe etc from time to time.

To meet Power Factor in IPSC using APS450 and 124gr projectiles, your gonna need to be up towards the 4.0gr as well depending on length of barrel. So I dont see how 3.0gr'ish loads are gonna be giving you over pressure.
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Re: 9mm- max pressure and seating depth

Post by BadShot » 04 Feb 2021, 6:21 pm

Don't know if LRN makes much difference, I run 3.9grn APS450 behind a 123gr FMJ all day long, gives around 1100fps.
3.7gr on a 135gr Plated HP
3.5gr on a 145gr Plated HP
Federal SPP's look flat, CCI & S&B SPP's look OK.

I had some Coated Lead RN 125's from when I first started reloading, I put 3.4gr APS behind them and was completely underwhelmed, I haven't chrono'd them as I don't intend to use them, very smokey. I don't know if that was from low-powder or the coating.
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