Re: need some load data for 10mm auto
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Clark</div><div class="ubbcode-body">No, I am not kidding, but the loads I mentioned were experimental, not practical.
You can follow recipes in a load book, and you can go advanced and work up your own.
To do an incremental work up in a semi auto pistol, I would make a series of handloads with increases of 0.1 gr of powder. In a cartridge box, if they get spilled, they are worthless, unless the load is written on the case with a Sharpie. A Post it map in the cartridge box with a map of which load is which will help.
The bullets need clearance. A handload work up with more and more powder, until the bullet does not seat as far, will make surprise failures. Each cartridge must be tested to fall in and out of the chamber.
If a gun blows up, there are many secondary failures. What to watch for in the work up is primary failures.
Wrap the pistol with a towel and shoot each round one at a time, with the magazine in the pistol.
Catch each case with the towel, look at it with magnification, and put it back in the cartridge box before resuming the work up.
Before working up, I would put a case in the barrel, and scribe a line on the case with a needle that outlines the feed ramp.
Measure the case base to scribed line max distance.
Cross section another case and measure the web thickness.
If the two measurement are equal, there is perfect case support.
The amount the the scribed line measurement is bigger is the amount of unsupported thin case wall.
9mm will be a .160" web. The line should be .180" or less.
40sw will be a .180" web. The line at .235" is poor.
10mm will be a .180" web. The line at .235" is poor.
45acp will be a .180" web. The line at .235" is poor.
The things you are looking for that will stop the work up:
1) Guppy belly case bulge forms on the brass 90 degrees from the extractor mark[from poor case support, a grain or two higher and it blows a hole will damage a few gun parts. Another grain or two and the case head blow off, many gun parts will be damaged and the shooter and bystander can get injured.]
2) primer piercing [magnum primer cups are thicker and firing pin holes can be bushed]
3) primer falling out [primer pocket and extractor groove too close, the worst is 10mm, the second worst in 7.62x39mm Large Boxer]
4) barrel splitting [happens in CZ52s. Don't work up hot loads in CZ52s. The old load books are wrong. I have contacted the authors.]
Once you have found a real limit, the practical load should back off 6% powder charge per Vernom Speer 1956.
In semi handguns there is another limitation, recoil.
If the cases fly more than 5 feet to land on the ground, the recoil spring is inadequate and the slide is hammering the frame. A little of this is ok, but too much can wear out the gun, the bones, the nerves, and make a guy flinch.
link to an old post of mine calcualting how far cases fly
If the recoil spring force is increased with triple springs with right hand twist on the inner and outer and left hand twist on the middle recoil spring, then 40 or 50 pound is possible.
This will create other problems, the slide will move so fast forward that the chamber will come up empty. The mag spring can be doubled up to speed the ammo rise time, but this makes the magazine hold one less round and takes a big effort to load.
The grip required to chamber a round with a 50 pound force at the rear of slide travel is only possessed by big strong men or little girls that put the slide in a vise.
One can increase the mass of the slide, but that makes it heavier to carry.
What does it all mean?
If one has improved case support, he can work up hotter loads, until the correct recoil spring force becomes a problem. </div></div>
Now THERE is a wealth of information!
I have no intentions of chasing a velocity record with my 10mm, I'm sure it can be an addicting pursuit, but I have several other time consuming ones already I'm not sure I can handle another one. My G29 is a carry weapon and as such I want it to 100% reliable as Glock designed it. I'm pretty sure I can tweak things and make changes here and there, but for the sake of putting some lead into a bad guy, I don't need it to come out with 44 mag velocities. The hot 10's will do just nicely for that.
I will probably end up getting bored at one point and seeing how hard I can push a 40 case without making any changes to the pistol.
I will take a look at the amount of support that is in the conversion barrel, thanks for that tip. Sounds like you've got quite the time involved in this, thank you very much for the help.
I'm still shocked at how fast you can push a properly supported 40 cal round.
