800x, and velocity s.d.

[sqlbullet]

I am pretty sure Kevin at Underwood ammo could give you a list of guns he has replaced.  There is a reason every boutique ammo maker went to 800X...Same concept you are pursuing now.  And there is a reason all of them have abandoned it...There are common circumstances in which  pressure become erratic.

You are correct that I cannot cite a source from IMR/Hodgdon group about why they stopped at 30K psi.  They don't usually comment on what they don't publish.  But I can assure you that given the appetite that 10mm fans have for velocity, if they could get there with 800X they would.  It's money in the bank if they could.

I will agree that the vast majority of catastrophic ammo failures by handloaders are going to be with fast powders.  For one thing, as you correctly state, it is far easier to not notice an over-charge mistake.  A much bigger contributing factor is that for "practice" level loads the economy is in the fastest powder that can make velocity.  I can load way for 1000 fps loads with 231 than with Longshot or 800X, and I am more likely to find a deal on 231 as well.  Shear volume of reloads is going to tip those stats.

The reason lots of load data disappeared over the last 30 years is the appearance of the very technology you want to use to test your loads: The piezoelectric pressure sensor.  The copper crusher method which was used to originally develop those loads you cite was crude.  It gave a rough idea of overall pressure.  PE sensors connected to high frequency sample instrumentation gave data down to the fraction of a micro-second.  And in that data they realized there were spikes that could be dangerous.  The new sensors revealed that this data was not as safe as the previous test method indicated.

Good luck in your quest.

[Graybeard]

'With the short time I've used 800-x (under 500 loads),..I can tell you that is does a pretty good case fill. I have not tried to compress it,..and I don't know if it "likes' compression like H110 does, etc., But I would like to know how much 800x the case would hold,..and still let you seat your bullet properly."

So are you actually considering loading as much 800X as you can fit under a 175gr cast bullet? Are you also considering making a compressed load?

Sqlbullet is dead on, btw.

[The_Shadow]

Well much like Blue Dot, 800X was more of a shotshell powder.  It did however prove to be quite efficient in cartridge case ammo as well.

That being said, I know some guys that ran the original 800X load with the 135 grain bullets and they experience extreme pressures and one had a case failure that cracked the frame on his G-20.
I have loaded beyond the loads listed with the 200 grain bullets...So the data needs to be understood and slowly worked on what works in you own firearms with bullets you work with...

Warning this DATA has been proven to be too high pressure wise


And this is the IMR Data, so you can look over the pressure info to compare


Having done the pull-down documentations of Underwood's early loadings when he used 800X showed some "SMILED" cases and blown primers in my S&W 1006 with 22lbs spring. This info listed below were tested by me after putting the cartridges back together

Underwood 135gr Nosler JHP
Ballistics Information: 10mm Auto
Muzzle Velocity: 1600 fps
Muzzle Energy: 767 ft. lbs
IMR800X 11.8 grains yielded Tested Velocity: 1738 fps
Case Data: expansion measurement's: Diameter 0.4325" "Smiled" 0.4295" primer blown out, no ejection, case stayed in the chamber but loose. 

Underwood 155gr Hornady XTP
Ballistics Information: 10mm Auto
Muzzle Velocity: 1500 fps
Muzzle Energy: 775 ft. lbs
IMR800X 10.8 grains  yielded Tested Velocity: 1503 fps
Case Data: expansion measurement's: Diameter 0.4270"-0.4280" primer slightly flat, (0.4280") is the size of the S&W factory chamber.

Underwood 165gr Speer Gold Dot
Ballistics Information: 10mm Auto
Muzzle Velocity: 1400 fps
Muzzle Energy: 718 ft. lbs
IMR800X 9.6 grains  yielded Tested Velocity:  1415 fps
Case Data: expansion measurement's: Diameter 0.4275"  primer slightly flat  (Some Underwood loads showed 10.2 grains 800X by another forum member)

Underwood 180gr Hornady  XTP
Ballistics Information: 10mm Auto
Muzzle Velocity: 1300 fps
Muzzle Energy: 675 ft. lbs
IMR800X  9.4 grains  yielded Tested: 1326 fps
Case Data: expansion measurement's: Diameter 0.4275"  primer slightly flat

Underwood 200gr Speer GD NFP = not for the public!!
Ballistics Information: 10mm Auto
Muzzle Velocity: 1166 fps
Muzzle Energy: 603 ft. lbs
IMR800X  8.4 grains
These were what were loaded for Jesse when he sent the bullets to UW to be loaded

Underwood 220gr Hard Cast
Ballistics Information: 10mm Auto
Muzzle Velocity: 1200 fps
Muzzle Energy: 703 ft. lbs
IMR800X 8.4 grains yielded Tested Velocity: Tested Velocity: 1209 fps
Case Data: expansion measurement's: Diameter 0.4285"  primer moderately flat, also had some leading.

[Muskrat]

One thing I've observed with 800x is that it gives the smallest velocity increase with a longer barrel of any powder I've used. I only picked up 16 fps going from a 6' to a 8" barrel with 800x, while I'll  normally pick up 50~80 fps with other powders and the same bullet.

[Graybeard]

One thing I've observed with 800x is that it gives the smallest velocity increase with a longer barrel of any powder I've used. I only picked up 16 fps going from a 6' to a 8" barrel with 800x, while I'll  normally pick up 50~80 fps with other powders and the same bullet.

That's really interesting. Reviewing my testing notes, I got exactly the same average FPS with 10.0gr of 800X out of my Delta Elite as I did with 9.4gr out of my 5" Kimber, 1309fps. This was using 180gr XTPs. In my gas operated 10mm AR, 16" barrel, I saw the biggest increase in fps with the 10.0gr load and the extreme spread went from 29fps to 19fps. No weird pressure spikes with the AR. Also very likely an accurate load.

All that reinforces my belief that different bullets, chambers, bore diameters, have a bigger effect on the performance of 800X than some other powders. I kind of hesitate to use the term "forgiving" about certain powders, but I have noticed that some, like BullsEye, LongShot, can give good performance with a + or - .2gr variance. That doesn't seem to be the case with 800X.