I've recently decided to start using 800x. (Kimber FS 1911), What a  pain in the rear it is for a powder thrower to be consistent.   Anytway,. Took my chrony out to check things out,..and at 9.3 gr. 800x (I don't believe it is in current load books),. I am getting 1275 fps with quite a LARGE standard deviation,. I assume this is completely due to inconsistent powder charges (I didn't trickle these in at all,..just checked them and had my powder cop set so they wouldn't get too out of spec).  So I had some empty 44 mag cases,..and two or three weights of bullets I wanted to try 800x in,. And so I used my Hornady auto charge (not sure the exact name I am supposed to call it) and let it trickle each charge to exactness.  All I can say is HOLY CRAP,.. When trickled to perfection, I was getting readings where all velocities were within 5 fps of each other.    Of those of you who use 800X,..AND TRICKLE your loads down to the exact amount,....are you getting standard deviations as small as I was in my 44 mag.
     I will be trickling my  next loads (don't know when that will be),. and will be hoping they are all nearly exactly the same muzzle velocity.    I have a hunch I.M.R. stopped at 30,000 psi because they knew full well there is not a powder thrower on the market that can make 800x charges very accurately and percentage will have a healthy overcharge.
    OK, Let me know how your trickled handloads with 800x do as far as standard deviation is concerned.

PUKE, What bullets were you using?  180 grain FMJ? or JHP?

Yes, the 800X begs to be match grade tricked loads, I set my powder drop to exact or just low and trickel them up to balance the beam of the RCBS 5-10.  Yes it does make a difference with all the 10mm powders when the loads are exact...

I'm shooting hardcast. It's a lee truncated cone 175 grain bullet mold,. I believe the alloy I am using comes in at around 177 or 178 grains, but don't quote me,..my notes aren't in front of me right now. I use gas check molds for bullets in my magnum revolvers,..but the 10mm isn't really hot enough to require gas checks. I've shot a handful of jacketed in the past, as well as some factory,..but, for the most part,. I stick with the hardcast that I do myself.

That's cool I like to shoot my cast bullets too...

I use 800x and hard cast bullets a lot. I use a Hornady electronic powder dispenser instead of a powder measure.

Here are some chrono results fired from Glock 40 and 20 both had KKM barrels.

The load tested was a Montana Bullet works 200gr WFN and 8.2grs of 800X

G 40 1159,1214,1157,1186, and 1178

G 20 1151,1141,1137,1144, and 1115

I did not get any signs of pressure I'm going to try 8.4grs next.

 I do have that Hornady Electronic powder thrower.  I will be using it when I get enough empty cases to do another loading session. Probably 9.3 gr.  I am so curious to see if the standard deviation goes down to a few feet per second when I use the Hornady to dial them in. That Hornady DOES try my patience.

I use some 800x...not a lot. I haven't used it enough to even know if I really like it. Honestly I bought a pound because it was what Underwood was using for a while and I like playing with different powders. I recently loaded up a hundred 200 grain Gold Dot's with 8.2 grains of 800x...accurate (why I chose that load), and while not as much velocity as is available, enough for me.

After trying several ways of measuring, I finally settled on filling a powder trickler with 800x and weighing each load on the scale. Doesn't take many loads before you can just about nail it to a 1/2 grain with the first dump, then trickle out the rest.

I tried using a reduced throw in my Redding Competition power measure and then trickling up to what I wanted, but it was a lot slower than just using the trickler from the start, at least for me.

I generally don't load anything very close to the redline, but any load that's hotter than 80% of max get's hand weighed, so I don't see 800x as being any more difficult to work with than any other powder for those loads.

Whether 800x is any better or worse than other powders for hot loads is beyond my expertise, though I'd be interested to hear from others who know more than I do.

Underwood was using 800x extensively for everything from 135 grain right up to 220 grain bullets. It seems like a pretty fast powder for the heavier bullets, but burn rate isn't everything. I (and most people I know) assumed that Underwood moved away from 800x because of the difficulty inherent in measuring it, but who knows.

I don't load four-hundred self-defense cartridges a year, so if 800x does something special, the annoyance of measuring it out is nothing to me.

The thing about 800x is that it gets you power without  having to go to high pressure. I think the 10mm is rated at 37,5kpsi max or something like that (although I hear that the original bren ten developement folks went wayyyy higher than that.),..And a regular high velocity load of 800x is around 30kpsi.  So,, my question is,...can you even get enough 800x in the gun to do a kaboom?  Wish I had the cash to send loads off to test labs with pressure barrels,. That would really be nice.

I would definitely say you can load enough 800X to get a kaboom. I believe it was the old Hornady manual that listed a 10.0gr max with their 180gr bullets. That has been reduced to 9.4gr in the current edition. I worked up to that 10.0 gr load years ago and tested it in my blued Delta Elite. It was really hot. Primers were pretty flattened and the recoil was up there. The average velocity was 1309fps with a 29fps extreme spread. I was using 180gr XTPs. The Delta Elite has had a lot of rounds through it and some pretty heavy springs.

Fast forward several years and I was testing 10mm loads in my nearly new, stone stock, 5" Kimber 10mm. 9.6gr of 800X got me to almost exactly the same numbers. I was working up loads for my 10mm AR at the same time. Perhaps foolishly, I ran two 180gr RMR FMJ rounds with 10.0gr of 800X through the Kimber. The first came in at 1381fps and the second at 1430. The second round caused the slide to come back so fast it pushed down the rounds in the mag and stood the top one up straight, jamming the gun. That's the closest I've ever had to a kaboom. Needless to say, I stopped there. The gun was fine, but I knew I was right on the edge of a disaster.

FWIW, I've also tested LongShot and can get the same velocities with a low extreme spread, from the same bullets. The bigger bonus with LongShot was no overpressure signs and no weird pressure spikes. Power Pistol has been right up there, too.

I don't think there is any inherent safety to using 800X in 10mm, actually quite the opposite. It is a performer if you're meticulous in your workups, there's no denying it. If you're pushing it, the use of a chronograph is a must.

FWIW, I think Underwood changed from 800X to LongShot for two reasons. First that it meters better and second that they've reportedly been very good about replacing people's guns that have blown up using their ammo. The latter eats away profits and reputation pretty quickly.

I've used power pistol a lot, 800-x some,..and haven't yet used longshot on the 10. I am going to be loading some with that soon,..I've got a couple pound of it around here somewhere. 
    By the way,..I thought Ka-boom refers to blowing your gun up,..Not wrecking the slide, etc.,  Many people who have done double charges in 1911-style pistols (or glocks, for that matter) have had the wonderful experience of the slide slamming back (sometimes wrecking things,..sometimes not,...._) .........and the magazine getting blown out the bottom of the gun...................and a short time later a tiny trip home to get a new pair of shorts.

I didn't say I had a "Kaboom," I said that was the closest I've ever had to one. It's a goal of mine to not actually blow up a gun

With the jump from 1381-1430fps between identical, hand weighed, 180gr rounds, I would call that a wicked pressure spike. Especially considering the slide speed issue I described. The first one was probably right around max pressure and the second was getting into proof load territory.

All I'm saying is if you're chasing speed, 800X isn't inherently safe as you get near the top end. Your fingers and your face aren't worth another 50fps.

Good luck with LongShot. I've gotten the same velocities and consistent speeds from it, without any surprises.

Quote from: puke on April 05 2020 09:32:08 PM MDT
The thing about 800x is that it gets you power without  having to go to high pressure. I think the 10mm is rated at 37,5kpsi max or something like that (although I hear that the original bren ten developement folks went wayyyy higher than that.),..And a regular high velocity load of 800x is around 30kpsi.  So,, my question is,...can you even get enough 800x in the gun to do a kaboom?  Wish I had the cash to send loads off to test labs with pressure barrels,. That would really be nice.

Um...I'd get a mentor before continuing to reload. Just saying.

Quote from: puke on April 04 2020 02:08:49 PM MDT
... I am getting 1275 fps with quite a LARGE standard deviation...

Quote from: puke on April 05 2020 09:32:08 PM MDT
I think the 10mm is rated at 37,5kpsi max or something like that
...
And a regular high velocity load of 800x is around 30kpsi

These two statement are related and not in a good way.  The reason the "standard" load stopped at 30K PSI is because in the lab they started getting erratic pressure results above 8.7 grains.  You are too, which is why you are seeing large standard deviations.  Were I a betting man I would bet if you keep going on this path you are going to learn more about a "Ka-Boom" than you want to.

Stay safe and good luck.

With 800x, trickled in my hornady auto charge,.. in my 44 mags. my s.d. is incredibly low...like 5 or less fps.
It is not as low in my 10mm, that's for sure.  I just did (yesterday) about 3 mags. full,..trickled by my hornady auto charge. Still a  s.d. of 20 or 30 fps. give or take, velocity was  avg. 1270ish 177.5 gr. hardcast. I don't yet know the answer to that (why the s.d. is near zero in a 44 mag and not the same in the 10mm) unless my auto charger was acting up.  It could also be that a semi-auto just doesn't get as low of a  s.d. due to how they operate.

When you make a statement that  IMR left the max load at 30,000 psi,..because the pressure was erratic,..I look and cannot find that statement made by IMR  at the time they did the load development....anywhere...anywhere on this planet...And I've been looking for a long time.  The pressure will be erratic with erratic charges,..that's a given. But erratic under a certain charge? ...The same charge they list at 30,000? Should it have said 30,000 +/- 10kpsi? Maybe it should have. I don't know on that one.

The chamber wall thickness of my kimber 10mm 1911 is quite a bit thicker than a 44 mag. and for that matter,..is thicker than the 454's that I have data on. I've owned two 454's, and both had cylinder  (outside) walls around .110",.. The kimber is closer to .125 or more (didn't use the Mititoyo on the Kimber,..so the blade width of the crap one from Cabelas will overstate the thickness quite a bit more than the thinner Mititoyo will).

I have personal friends who have had kabooms. EVERY......SINGLE.......ONE.......of them was using a fast powder and either had a detonation or a double charge. I am 60 and still waiting for someone I know to have a kaboom under a too heavy dose of a slower powder...one that fills the case. (I believe that in these types of court cases...for a defense,  the ammo. mfgr. states the powder they use,..and then says something like: you can't get enough of this powder in the case (even if you want to) blow the gun up,..and then they proceed to wait A LOOOOONNNNGGG TIMEEEE for the prosecuting attorneys to try and prove them wrong. This kind of thing usually just wears a gun out faster than lighter charges would. An acquaintance of mine  recently did a double charge of bullseye in his 45 glock (he was new to reloading, and quite young)..and it blew the magazine out the bottom of the gun,..and scared the crap out of him,. but the gun was ok, all he needed was a new pair of shorts.

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. 

I suspect that after IMR and Hodgon became the same company,..the old 10mm imr data was left "as is" originally and then no longer used.  I am guessing that there is a good chance that the original folks involved with the 180 gr. 800x testing are no longer with us. At some point Hodgdon decided they would use their own data and the IMR data disappeared.  The original 357 mag was about 1550 fps. And the load is well known,..about 15.3 to 15.5 grains of 2400. under a 158 grain bullet. Explain to me how a "normal" load, becomes almost non existent after a few decades?  Did all the original 357's blow up because they didn't like the original load? (I load this exact load for all my 357's..and the velocity is exactly what it was back then in an 8" Registered Magnum.) 

The last paragraph leads to the following question: Where are all the blown up 10mm guns that caused the original data to be "pulled" from officialdom? I'll wait.................................              ..................still waiting.   I hear some of the original 10mm 1911's back then weren't as strong as the  ones now.................so I'll even wait a little longer while someone finds the information.

When I have some extra money and connections,..I fully intend to send some rounds to someone with a pressure barrel so I can answer this once and for all. With all the internet yapping you would think that someone out there would send rounds and have them tested. They do that  for revolvers quite often.

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.