Prochrono problems i think


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jake1369
April 20, 2013, 09:31 PM
hello, i'm still new to reloading but i think i have a problem with my ProChrono. i loaded some 9mm 124gr gold dots with 8.7gr of aa7, cci 500 primers and a OAL of 1.123. my chrono reads 1255fps out of a para p-18 with the 8.7. but speer #14 shows 1180fps with 9.1gr aa7 and a OAL of 1.20. this same load shows 1105 out of my little sig p239. is there some way to test this chrono?

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rcmodel
April 20, 2013, 09:47 PM
Do you have a .22 rifle or pistol??

Or some factory loads for your 9mm?

On the other hand 8.7 grains of AA7 is nearly a full grain over the 7.8 Max load with a 125 Sierra in the Lyman #49.
And it shows 1,119 FPS.

And Accurate data shows 7.4 is MAX giving 1,090 at 34,724 PSI with the bullet you are using.
http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf

Where exactly did you get your data showing 8.7 grains?? :eek:

Sound's to me like you don't have a chrono problem.
Sounds to me like you are about to blow yourself up using bogus data you found somewhere!!

rc

jake1369
April 20, 2013, 09:53 PM
Speer #14 shows their GDHP with aa7 at 8.1 start load for 1077 and 9.0 max for 1180

rcmodel
April 20, 2013, 10:04 PM
Speer #13 shows 8.0 Start = 1,159
And 8.9 Max = 1,249.

Still, you need to use more then one data source before jumping in with the highest load you can find anywhere!

Unless you are shooting the same S&W 5906 they used in the #13 manual?
You are HOT with your gun, and your chronograph is accurately telling you so.

And I don't care what Speer #14 says!

rc

jake1369
April 20, 2013, 10:26 PM
roger that, thank you for your help. I thought the speer manual would be good for speer bullets. I didn't start at 8.7, i started at the 8.1 and went up. the primers and brass both looked good. i thought my chrono was bad. again thank you for your help i have a lot to learn. there is so much conflicting data. accurate states one thing and speer states another. easy to get hurt.

rfwobbly
April 20, 2013, 10:28 PM
I agree with RC. The reason speeds are listed is because it's the easiest way for you to know your chamber pressures are safe. The max speed is set by the max chamber pressure. You said it yourself, anything over 1180 fps has a dangerously high chamber pressure.

If you'd like to stay in reloading with all 10 fingers intact, then friend it's time to back off that load.

rcmodel
April 20, 2013, 10:32 PM
Well, probably not hurt, too much.

But easy to beat a good gun to death early, or blow a case after it has been reloaded 16 times.

I suggest you go with a broad spectrum of data sources, and kinda average it out, if you will.

If you need bleeding foreskin +P+ 9mm loads?
Buy Buffalo bore factory ammo.
Or a bigger gun.

BTW: I think your Chrono is working just peachy keen with the load & gun you are using!

rc

1SOW
April 20, 2013, 11:40 PM
The 124 gr Speer G.D. bullet is claimed effective at not much over 1100 FPS
I also load for a P239 and have some at 1200 FPS (different powder.---also measured with a Pro-Chrono. ), but plan to back off that by 50FPS "when I can find some more "G.-D." bullets"!!

Yours is likely a compressed load, eh?

gamestalker
April 21, 2013, 02:48 AM
I load some nasty 124 Gold Dots too, but I worked up from around mid range to get them up where I wanted them in terms of velocity. If you insist on +P loading, which is your own prerogative, and I'm certainly no one to speak against it, at least start out some where in the mid range of the data. 9mm is already a high pressure handgun cartridge (32,000 psi +), so without any definitive pressure signs to warn you, you can get hurt without seeing it coming.

Be safe!

GS

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