Oh the PRESSURE!!!

[Geeman]

Pressure Trace II...



The strain gauge.




I spent the weekend getting this set up, and next weekend I want to give it a try.  I have a series if stepped loads of BE-86 to try go get pressure info on, as well as proceeding to some of the factory Underwood rounds I have on hand. 

Greg

[sqlbullet]

We need a drool emoticon.  Soooooo jealous.

[The_Shadow]

Well man that's going to be a very very interesting data set, if it all goes according to plans!
Best of luck!  Don't put your eye out with that thing! 

[Geeman]

I just got around to getting the thing set up.  Its a good thing I got extra strain gauges.  The first try I had way too much glue on the thing.  Sets up fairly fast, but getting the damned thing off was a bigger chore!!!!  I had a major hassle trying to figure out what was keeping the program from loading on the laptop.  That only took 4 hours

Now I just need to see if its functional or if I have done something incorrectly.

Greg

[The_Shadow]

So you will need to establish a base line pressure to work from and set the parameters of the program for unknown loads? 

At least Hodgdon still has some pressure values that you can dial in with...I have many older printed data that also contains the pressure values if you need and I'd be happy to share what I have with you.

[Geeman]

Lots (too many) variables to keep up with.  The chamber in the Encore are MUCH tighter than any auto loading pistol, which leads to higher pressure.  The setup should be quite predictable.  The barrel is cylindrical, the cartridge is cylindrical, and it readings should be quite close to actual pressures.  I'm believing that the results I'll get will be high by a few thousand PSI (maybe 3k or so) if I'm estimating correctly.

It may very well be more useful correcting this with a known load, just to equate the results to the type of firearms typical to the 10mm.  Actually, I can set up two different "barrels" in the software, one uncorrected and one set to a known pressure value. 

I'm sure the learning curve is only beginning. 

Greg

[Geeman]

So you will need to establish a base line pressure to work from and set the parameters of the program for unknown loads? 

At least Hodgdon still has some pressure values that you can dial in with...I have many older printed data that also contains the pressure values if you need and I'd be happy to share what I have with you.

Shadow, since you offered...

The powders I have are Pistol Power, 800x, Longshot, CFE Pistol, and BE-86

The bullets I have are 165 GD, 180 GD, 180 HAP, as well as Nosler 135g, 150g, and 200g

Primers on hand are CCI 300 and Winchester LP.

If there is combo I could put together with published pressure data I'd be grateful.

Greg

[The_Shadow]

Nosler 135g
Hodgdon list the Nosler 135 grain JHP over 9.0 grains CFE Pistol @ 1404 fps 26,900 psi COL 1.2500" Winchester LP  5" barrel
Hodgdon list the Nosler 135 grain JHP over 10.2 grains CFE Pistol @ 1551 fps 35,900 psi COL 1.2500" Winchester LP  5" barrel
Alliant shows a 135 grain JHP over 10.6 grains Power Pistol @ 1,530 fps 35,600 psi COL 1.2500" Federal 150 LP  5.5" barrel
(Hodgdon shows Winchester cases Alliant N/A)

Sierra 180 grain jacketed hollow cavity (while these are not the Speer Gold Dot or Hornady HAP they may be close)
**(Speer Gold Dot may show less pressure(concave base) and the Hornady HAP about the same flat base)
Hodgdon list the Sierra 180 grain JHC over 8.5 grains Longshot @ 1221 fps 31,000 psi COL 1.2500" Winchester LP  5" barrel
Hodgdon list the Sierra 180 grain JHC over 9.5 grains Longshot @ 1287 fps 34,600 psi COL 1.2500" Winchester LP  5" barrel
Hodgdon list the Sierra 180 grain JHC over 8.7 grains IMR800X @ 1210 fps 30,000 psi COL 1.2500" Winchester LP  5" barrel
Hodgdon list the Sierra 180 grain JHC over 6.7 grains CFE Pistol @ 1082 fps 25,600 psi COL 1.2500" Winchester LP  5" barrel
Hodgdon list the Sierra 180 grain JHC over 7.6 grains CFE Pistol @ 1208 fps 25,600 psi COL 1.2500" Winchester LP  5" barrel
Alliant shows a 180 grain JHP over 8.7 Power Pistol @ 1,240 fps 34,900 psi COL 1.2500" Federal 150 LP  5.5" barrel
(Hodgdon shows Winchester cases Alliant N/A)

Still there will be variables such as the brass being used, its sized dimensions, but you can make them all the same for your testing for repeatability purposes.

I'll search for more info to add...Good luck!  Many of these have been on the books for 10mm since early 90's and repeated through the years

The shame of it is many powder publications DO NOT show any pressure values (which is bad in my opinion) but I suppose it satisfies their corporate lawyers...

[Geeman]

That should be enough.  I just need a one to use as a calibration load and a another one or two to make sure that calibration makes sense!

Thanks,

Greg