Loaded some 9mm last night and misread calipers. COL should have been 1.165" and I loaded 1.065". Will these be safe to shoot? I used 147 gr Berrys RN with 4.3 gr Power pistol. Working on a USPSA minor load. Thanks and Happy Turkey Day.

I would NOT shoot them - 0.1" too deep is a lot in the relatively short 9mm cartridge. Just my $0.02.

NO!!!!!

EarlFH

Do not shoot these rounds. .1" shorter is a massive difference in bullet seating depth and your rounds are unsafe. Pull them as soon as possible so they don't wind up in a gun by accident.

I am fairly new to reloading 9mm, so could someone tell me the effects of shooting something that is only 1/8" shorter than standard? I have heard that length of cartridges does not have any major effect in revolvers with standard loads, other than it would be bad for accuracy. Is this true?

Revolver cartridges such as 357, 44 Mag, 45 Colt have much larger case capacities. There's usually a lot of space left over even with a bulky powder charge, so you can play with COAL a little bit.

Small, high pressure pistol cartridges like 9mm and 40 S&W are very different. This is a small case capacity to begin with, so if you seat the bullet deeper you take away case capacity and add a significant amount of pressure. Bullet length also plays a part. A longer bullet, even seated to the same COAL as a shorter bullet in the caliber, is reducing internal case capacity. In the OPs case, he's using the longest 9mm bullet, the 147gr, seated to far below a normal COAL. Very unsafe.

The small case size on the 9mm makes it a very unforgiving round. It's a very high pressure round and I keep a very very close eye to COL per bullet used and powder used.

In a low pressure round as say a 38 spl it may not have to be quite as exact as a high pressure round.

With a 4.3 gr load of Pistol Powder I think he's at the low end for a load but with that much difference in COL I'd not shoot them.

What can happen is the gun can be blown up! Other than that, not much.

In cartridges for semi-automatic pistols the capacity of the cartridge with bullet seated is much smaller than for most revolver cartridges. Overall length is not the problem, it is the reduction in volume of the "combustion chamber", which increases loading density dramatically. With a 147 gr bullet in a 9mm case, the distance between the base of the bullet and the inside of the case head is ca. .200", maybe a little less. If the bullet is seated .100" too deep it reduces this dimension to about .100", 1/2 as much volume, or slightly less. This has the same effect as increasing the powder charge by about 50%, which will double chamber pressure. In a high-intensity cartridge like 9mm this is very significant.

This link was posted by MaximumBob in another thread. It has to do with the 40 SW and the 180 bullet. It shows the increase in pressure. I myself do not agree with the author on the just the 180 bullet, as this can happen with any bullet in any high pressure caliber. If a 165 gr bullet is seated too deep it's not good either He also did not list the powder used BUT the bottom line is correct. Seat a bullet too deep and bad things happen. As mentioned bad things happen faster and more so is short high pressure calibers.

So the principal is the same for a 9mm.

CALIBERS -- Why the 180gr Bullet is a Bad Choice for .40 S&W

__________________
Still Running Against the Wind

Ah yes, I wanted to post that chart but didn't bookmark it previously. Those pressure readings pretty much say it all.

A more detailed explanation. The Ideal Gas law is PV=NRT. P equals Pressure, V equals Volume, N is the number of gas molecules, R is Boltzmann's constant, and T is Temperature. Do a bit of algebra and the equation that relates to determining Pressure is P=NRT/V.

Now, and intersesting set of effects take place during combustion in a firearm. One is that the Volume of the combustion chamber is increasing as the bullet moves down the barrel. Ideally, we would like to see that bullet moving at a rate that maintains a constant pressure because bullets are rather heavy and don't change velocity very quickly in relation to a rapid change in pressure. One thing to always remember is that what is desired during the powder ignition is a steady BURNING of the powder, not a near instantaneous DETONATION. Propellants WILL detonate if the pressure exceeds a certain value at a certain temperature and the result of detonation is a near instantaneous massive increase in pressure. Since the bullet can't get out of the way of that pressure spike, the result of Detonation is usually something getting blown up. Two factors that push a powder burn towards detonation are Temperature and Pressure. If you play around with the Ideal Gas Law algebraically you'll find that increases in Volume reduce temperature and/or Pressure.

Now picture a case that has been loaded "short". You are starting the whole process with a reduced case Volume AND with a bullet that is moving from a standing start. As a result, during the initial ignition the Volume isn't changing very rapidly at all. The end result is that Pressure and Temperature both rise very quickly and those rises can push the powder charge past the threshold for Detonation too rapidly for the slowly increasing Volume. The end result is usually a case rupture and resulting damage to the firearm and shooter.

This all makes a lot of sense. I am only loading target rounds and use 115 FMJ. Also using only 3.5 grains of Clays powder to produce a mild shooting round. If I want heavy personal protection rounds, I buy them.

Now I might be opening a can of worms here, but I also have used Puflon as a case filler to get even ignition with the small amount of powder in the case. Why does this not follow the normal warnings of not having enough space left in the cartridge? My velocities have been good - lower than factory and I am getting very low standard deviation.

Thanks for the info and from what I understand, I should be good to go as long as I keep the round COAL to specs.

That load should be in the upper +P limits with a standard 9mm case length of .754. Use at your own risk!

Pressures increase dramatically as case volumn goes down. So seating a bullet as little as 0.06" deeper can raise pressure enough to yield 100fps higher vel. That is like adding 1gr of powder. In a load already pushing max, that is dangerous.
The OP load is barely a starting load & seating that deep may be fine, but I would have wanted to test them &/o work upto that, not just put them together & assume they will be fine. PP is far more forginving than Clays, YG or other uberfast powders. Keep in mind, pressures are NOT linera once you pass max. The faster the powder the more steep the pressure curve.

Also dangerous w/ uberfast powders like CLays. Over powder wads are best used for small charges of fast powder in large cases to hold the powder in place. That just isn't needed in the samll 9mm case.

I don't use the Pufflon filler so I can't say on the 9mm. I always thought the the filler was for rifle rounds or black powder rounds that now use smokeless powder. The 45 colt and 38 spl come to mind that were blackpowder and are now smokeless. I see where I could use a filler there but don't.

I did work up to the 3.5 grains of Clays by watching velocities and whether they would cycle my S&W Sigma. I got consistent cycling at that level, but this load still does not cycle every time in my compact Kal Tec so think I am safe.

As many of you know, Puflon is powdered Molybdenum Disulfide. I first started using it in old black powder cases like 45-70, 45LC, 44-40, etc. and have found it to be a great help in eliminating the times I have had to push a bullet out of the barrel due to improper ignition.

I have only used it once in my 9mm and worked fine, but agreed that it is probaably not necessary to continue.

3.5 of Clays is right in the middle of the range of powder charges as listed by Hodgdons and produces about 1050 fps. It is, of course, very clean.

Show me a loading manual or powder makers web site that suggests the use of "fillers"??

Despite the fact that they are "airy" and light they still take up volume in a case and will change the whole pressure situation.

The use of "stuffing" should be left in a Turkey.

__________________
Still Running Against the Wind

Thanks guys. I feel really stupid, I have been using dial calipers for 40 years, but just had a lapse in concentration. I will pull those tonight. Happy Thanksgiving.

No, do not feel stupid. You are the opposite, smart.

You realized something was not right and asked and correcting the situation.

__________________
Still Running Against the Wind