https://m.facebook.com/story.php?story_fbid=pfbid02Nd6F2c55AzJrZUKnWi5YEyCVnVBytVm5o8xktpCwktrat4CVjy2VwgThAp2CQfWbl&id=100050382871199
The Facebook page where l have pictures of the cases.

AA#9's usually fills the case/compresses even within published data.
To me, that is engineered safety. Obviously not completely fool proof.

Old saying:  The difficulty in making things fool-proof is that fools are so darned ingenius.

I'll take that as a compliment.

14.8 Grains is probably pushing the limits for regular 10mm loads or more likely a bit over.   12.2 is a starting load and Hodgdon lists 30,800 PSI, while 13.5 is a max load and list 34,100 PSI.   That's an increase of 3,300 PSI for 1.3 grains of powder.  Your adding another 1.3 grains of powder which is adding at least another 3,300 PSI for a total of at least 37,400 PSI.  SAAMI max is 37,500.  However the more powder you add the less free space in the case so adding powder doesn't increase pressure in a linear manner.   

How much over 37,500 is the load is anyone guess.   It's not like a round running 37,500 PSI is safe and the gun can handle 100,000 rounds but then going up to 37,501 PSI is going to blow up the gun.   It's all just incremental wear and tear until the gun beats itself apart unless you do something really stupid.

Is it an unsafe load?   Probably not.   Your empirical evidence proves the isn't going to blow up.
Is it going to cause more wear and tear on the gun than a 13.5 grain load?  Yes.
Does this matter to you? 

I could be mistaken, but would think Underwood?s 135gr Nosler running at 1,600 fps / (ft. lbs): 768 would be darn close to the SAAMI max of 37,500 PSI. This load has to be one of my all time favorite factory loads.

https://underwoodammo.com/10mm-auto-135-grain-jacketed-hollow-point/

I checked with Underwood regarding the PSI of their 135gr Nosler rd. They told me is was?

Good morning,
That particular round PSI is at-36,900

Quote from: Reddog81 on December 08 2022 03:46:54 PM MST
14.8 Grains is probably pushing the limits for regular 10mm loads or more likely a bit over.   12.2 is a starting load and Hodgdon lists 30,800 PSI, while 13.5 is a max load and list 34,100 PSI.   That's an increase of 3,300 PSI for 1.3 grains of powder.  Your adding another 1.3 grains of powder which is adding at least another 3,300 PSI for a total of at least 37,400 PSI.  SAAMI max is 37,500.  However the more powder you add the less free space in the case so adding powder doesn't increase pressure in a linear manner.   

How much over 37,500 is the load is anyone guess.   It's not like a round running 37,500 PSI is safe and the gun can handle 100,000 rounds but then going up to 37,501 PSI is going to blow up the gun.   It's all just incremental wear and tear until the gun beats itself apart unless you do something really stupid.

Is it an unsafe load?   Probably not.   Your empirical evidence proves the isn't going to blow up.
Is it going to cause more wear and tear on the gun than a 13.5 grain load?  Yes.
Does this matter to you?

No. Because when I buy a handgun I buy it to use it. As far as for wear and tear. I use light loads or maximum loads or beyond that, and/or anything in between. Not only do I shoot the above load as noted, not all the time. That's what's good about hand loading. You can tailor the round to any application you want to use it for. If one was to shoot constantly the above listed round. You can go to a heavier spring. But my object was to see how a stock glock 20 would function with the above load without modifying it.
It's funny you say about wear and tear on handguns. Real quick. I have a former coworker that has a 1980"s or 80 Colt Python. He's not a gun guy. He just collects things. Example: Star War figures, Hot Wheels cars. Doesn't take them out of the wrapper which is called today blister packs. Colt python untouched by human hands. Literally. Nothing wrong with that.  The Colt python he has is untouched by human hands as far as for buying it from the ffl dealer to his possession. Today if you were fortunate enough by him that you can handle it. He literally has white cloth gloves for you to handle it. I told him why don't you shoot it. Even the light loads. I know he's not a gun guy. His reply was: I'll be putting wear and tear on the Colt Python. Well that's true.
His philosophy is different than mine. My Philosophy is. Use it, but don't abuse it.

I recently posted on another gun related forum about the use of Blue Dot and AA#9, and that both were often recommended for use in the 10mm. Another member, possibly a professional gunsmith, posted that neither powder had the proper burn rate for the 10mm. Especially the AA#9.

Quote from: Sailormilan2 on January 05 2023 12:32:47 PM MST
I recently posted on another gun related forum about the use of Blue Dot and AA#9, and that both were often recommended for use in the 10mm. Another member, possibly a professional gunsmith, posted that neither powder had the proper burn rate for the 10mm. Especially the AA#9.

Sounds like he didn't really know what he was talking about then. Blue Dot can be used for some very accurate loads in 10mm, although not the fastest. AA#9 works just fine in 10mm.

Quote from: Graybeard on January 05 2023 01:11:09 PM MST

Quote from: Sailormilan2 on January 05 2023 12:32:47 PM MST
I recently posted on another gun related forum about the use of Blue Dot and AA#9, and that both were often recommended for use in the 10mm. Another member, possibly a professional gunsmith, posted that neither powder had the proper burn rate for the 10mm. Especially the AA#9.

Sounds like he didn't really know what he was talking about then. Blue Dot can be used for some very accurate loads in 10mm, although not the fastest. AA#9 works just fine in 10mm.

Agreed. I sent the OP, who was looking for advice on reloading the 10mm, a private message to come to this Group for information on the 10mm. I have no idea if he has done so.