Under-charging

[ChiefPilot]

Aside from the dangers of getting a bullet stuck in the barrel and not noticing it before firing a second round, are there any other dangers to be aware of when underloading?

The reason I ask is my next reloading project is for .30 carbine, but the load data I have conflicts. The WC820 powder I have says to use AA#9 load data, and that USGI loads can be duplicated using 14.0gr under a 110gr FMJ. The data sheet that came with my Lee dies, however, shows a starting load of 11.0gr for AA#9, and a max load of 12.6gr. Clearly, this is a good bit below the 14.0gr load mentioned earlier.

To solve this, I thought I would load up 10 rounds with 11.0gr, 10 rounds with 11.2 gr, and so on and work up to a reliable load (I don't need to duplicate the USGI performance as long as the slide functions reliably). The worst that can happen with a low-power charge is that it won't cycle the slide on my M1 carbine, right?

Thanks!

 

[Third_Rail]

Undercharging can also lead to REALLY high chamber pressures. Be careful.

 

[wrangler5]

The Accurate reloading manual lists max loads of #9 as 13.3g for 100g Speer Plinkers and 12.6g for 110g Speer FMJ, with starting loads of 12.0 and 11.3, respectively. For these bullets with #9, Speer recommends a min/max of 12.3/14.3g and 11.4/13.4g, respectively.

I'd say that even if the max charge is 14, a load of 11+ isn't much of an "undercharge." Like Third Rail, I've heard that small charges can lead to catastrophic results. But my impression is that the problem comes from light loads of fast burning smokeless powder in black powder era cases (like light target loads using a few grains of Bullseye in 38 Special cases) where the powder occupies only a small fraction of the available space, and so can spread out in the case in ways that may avoid direct ignition by the primer flame. I don't have any 30 Carbine ammo, but from what I recall it isn't a real big case, and I'd bet that even 11g of #9 will use up a substantial portion of the available space.

So I think you're right, the biggest risk is probably going to be inadequate bolt function, but I wouldn't be surprised if even 11g cycles things properly.

 

[MNgoldenbear]

The light loads of fast powders are okay, and in fact are recognized as the best target loads in terms of consistency/accuracy (with most standard pistol rounds). With fast powders, the danger is multiple charges in a larger case. Ever see how much room is left in a 357 or 44 case when you drop a normal target load of Bullseye? You can put at least two, if not three or four charges in the case. A rangemaster once told me a guy fired a pistol there with unusually loud report and the gun tied up. When asked, he indicated that he had loaded the rounds. When asked about the charge, he said he didn't know -- he was just filling them up to the line that showed where to fill to. He then indicated the crimp line, the one at the base of the bullet on some commercial loads, that he had been using as his "fill line"! He was informed that he was lucky to still have his hand, to remove the remaining rounds if possible, take them and disassemble them, and get manuals and other information if he wanted to keep trying with his handloading.

It's light charges of SLOW powders that have been indicated in some detonations. Many load data sources indicate that slow pistol powder loads should not be reduced below recommended starting charges (e.g. Win 296, H110, possibly AA#9 may fall into this category). The causes of blow-ups with light charges are still apparently somewhat unclear.

Just looked up a reference - Jeff Bartlett's page, GI Brass http://www.gibrass.com/gunpowder.html -- note that he mentions (1) surplus powders vary in burning rate from lot to lot, (2) always start with a starting load and work up. Also, standard practice is, of course, to work the load up, since the max load in the test gun may be either above or below the safe max for your gun. Also note that he is selling three variants of WC820, each with its own recommendations for max loads, although the first two say to use AA#9 data. The reference to AA#9 data is just a general guide, I'm guessing. A starting load for AA#9 will probably be safe, and you can run a series of charges, as you said you planned to do, to see what the best cahrge would be (like any other load development). Hopefully you have a chronograph. When you get velocity similar to max velocity, you're probably at or near the pressure that the data was taken at, whether you are at the same powder charge or not. Probably best not to go past this unless you're sure that pressures are lower than max specifications.

 

[pcf]

The detonation thing has never been shown as a threat (or possibility) in modern, smokeless powder, small arms cartridges. Many unwilling to admit obvious mistakes will blame detonation. Navy deck guns are a different subject.

Slow powders do not burn well (consitently or cleanly) when there is an insufficient quantity present. A very small charge of slow powder will result in a squib load.

 

[Doug b]

Primer explodes moves bullet down the barrel and stops...powder ignites.
rule #1 violation,never shoot an abstructed barrel

 

[pcf]

I've ruined a revolver barrel firing a light load of slow powder, the result of a squib loads, followed by another round. The revolver did not "detonate".

Definite stupidity, I loaded 38 spcls with 3.0grs of w296 over 148gr wadcutter. The first round lodged in the barrel, the second round shoved both of them out (as best as I can guess). Leaving an obious bulge in the M10 pencil barrel. Of course one case does not set the rule.

Primer explodes moves bullet down the barrel and stops...powder ignites.
rule #1 violation,never shoot an abstructed barrel

How does a primer explode, force a bullet into the barrel, then ignite the powder charge? How far does the bullet have to be out of the case before it's dangerous? Why don't more pistols detonate when using small charges of fast burning powder. The obstruction is in place, and the powder is capable of generating a much higher volume of gas than the small amount of slow burning powder.

I've never seen anything in that suggest "detonation" in modern, smokeless powder, small arms is possible, other than in theory. But that's all that it is, an unproven theory. Proven: overcharges of powder, firing bullets into obstructed barrels, and firing out of battery will ruin a modern, smokeless powder, small arm. Detonation is something that people blame their mistakes on.

 

[klw]

Undercharges

The thought is that an under charge can detonate rather than burn yielding REALLY high pressures. The problem is that this occurs so infrequently that it is always written off to someone inadvertently getting a double charge in the case.

If I could be more careful I don't know how. When I started using a low charge of titegroup in my 500 magnum I knew that this was a possibility so I weighed each and every charge AND used a powder checking die. The charge wasn't REAL low but it was near the lower limit of what was recommended.

The gun detonated. Bulged the cylinder. Damaged the barrel. Totalled the gun.

I put this experience up on the Smith site. Responses ranged from real concern to comments about really stupid people should reload. But there were other comments.

A fair number of cowboy action shooters indicated that they too had blown up single action revolvers under similar circumstances.

I think that small charges detonate. I wouldn't use them. I'd also stay away from titegroup.

 

[Nando Aqui]

Failure-to-Fire in a Match...

I am contemplating getting a new (progressive) reloading press, and have been wondering about the potential for an un-charged or under-charged cartridge to get through.

I have seen failures-to-fire due to hard primers, or weak hammer springs, or whatever; and when racked, the complete cartridge is ejected, of course. My concern is that in the heat of a match, if a failure-to-fire occurs, and the shooter racks the pistol without the presence of mind to look for a complete round to be extracted and ejected, he/she could fire into a plugged barrel.

Consider the following scenario:

You reload 200 rounds of .45 ACP to use at the next IDPA match, competition is hot, and you feel that you are ready to really improve your last posted score. Unbeknownst to you, one of the rounds you reloaded got by with little or no powder.

In the middle of a COF, you pull the trigger, the hammer falls, but nothing happens. Precious tenths-of-seconds fly by, so you dismiss the failure-to-fire as an annoying pistol malfunction, and instinctively rack the pistol quickly, and pull the trigger. Kaboom!

Is it possible? If not an under-charged round, could a primer alone create enough force to lodge a bullet into the barrel?

Alex

 

[wrangler5]

<snip> If not an under-charged round, could a primer alone create enough force to lodge a bullet into the barrel?

A primer alone can certainly move a bullet out of the case. How far down the barrel it goes will vary. I mistakenly failed to charge some 44 Mag loads recently, and the primers were powerful enough to move the bullet part way into the forcing cone of the barrel, thereby locking up the cylinder. I recall having a 9mm squib load once that pushed the bullet out of the case and into the rifling, but not far enough to let the next round chamber. Other bullets in other barrels with other primers might move far enough to let the next round come in behind and . . .

 

[ChiefPilot]

... snip ...
Is it possible? If not an under-charged round, could a primer alone create enough force to lodge a bullet into the barrel?

I saw this exact thing at the range last weekend, or what appeared to be it anyway - shooting pulls the trigger with a resulting click instead of a boom. Racks the slide, finds empty casing. The .45 slug was in the barrel, and after it was tapped out the rifling marks were not quite to the end of the 230gr slug. I don't think he could have fully chambered another round but maybe...

 

[Doug b]

Gun powder burns

Detonation is an explosion,trust me on this one brothers if gun powder exploded we would not be allowed to have it.

 

[Doug b]

Primer power

I remember a few years ago a friend was shooting plastic bullets into a trap in his mobile home.These are powered by primers no powder charge.Now this fella is a really bad shot and sure needed the practice. Sure enough he missed the trap this .38 cal. plastic bullet shot through the paneling and the insulation and the aluminium siding. Wonder what a mag. primer would have done.Hello neighbor.

 

[Otherguy Overby]

Detonation!!

There's some people in Finland, where silencers are legal and they experiment with subsonic loads: http://guns.connect.fi/gow/gunwriters.html

Now on with the topic:

=============from: http://guns.connect.fi/gow/QA1.html

1) "When Lady Luck kiss you goodbye, it is still goodbye!" As small charge of powder as .2 gram or 3.1 grains of shotgun powder is able to blow up action of a .308 Winchester rifle. (My empirical knowledge is based on test-shootings with .308).

That charge is half from definitively minimum load with a jacketed bullet, weighing 123 grains/ 8 grams and about one third from a safe minimum charge for .308 Win. with 170 grains / 11 grams jacketed bullet. The very same .20 gram / 3.1 grains is good, safe and subsonic charge for .308 Win. with a cast, lubricated lead alloy bullet with nominal weight 93 grains. Powder used for test-shootings was Finnish VIHTAVUORI N 320 (a most close counterpart of German blank-cartridge powder, adopted in 1933 and used as a propellant of 7.9 x 57 mm Mauser subsonic "Nahpatronen", loaded by Finower Industrie GmbH during WW II).

Two known accidents were also happened with reduced charges of that same powder by S.E. Effect. One with halved Definitively Minimum Charge and another with third D.M.C. Charge was in both instances before mentioned .20 gram / 3.1 grains. Bullets were - of course - jacketed ones, weighing 123 grains and 170 grains.

According to my test-shooting records is one full gram / 15.4 grains of N 320 safe charge behind both of these bullets in .308 Winchester cartridge with a standard (non-Magnum) Large Rifle primer. Powders N 310 or CLAYS are as or more easy to ignite as N 320, and so fit for use in reduced charge loads. This is the very most important quality of a powder, when the subsonic muzzle velocity is aspired after. Fast burning-rate and clean burning of powder are also beneficial - if not essential - properties.

An overly-reduced charge is a good way to court disaster, but reduced charge detonations are never (?) happened with a first shot of a string, when the rifle bore is still clean and at least slightly moistened with oil or grease. Risk of S.E.E. is increasing when the bore is fouled with carbon, lead dust from primers and unburned powder kernels, when the oil or grease is shot away from the bore.

First signal of imminent danger is increased variation of bullet velocities. A bullet, lodged into the bore, scares me always to have nightmares in seven to fourteen next nights... Velocity variations are usually not progressive but undulating because of variable bullet friction in the bore. Especially that friction (hardness) of jacketed bullets tends to vary, when the powder pressure behind them is low. Unfortunately this pressure cannot be higher, if one is trying to get subsonic velocity with each & every shot from the rifle, giving usually Mach 3 readings of bullet speed - like .223 .

A main reason of S.E.E. is disorder of powder ignition. Powder charge does not burn after the explosion of a priming pellet. It smoulders like a German tinder, developing a cocktail of explosive gasses like nitrogen oxides, hydrogen (very reactive "In Statu Nascendi" hydrogen - not yet bound to H2 molecules), and carbon monoxide. When this highly flammable mixture of gasses catches fire from still smouldering solid powder remnants, may the "BANG !" be horrible. Mere three grains of gasses may literally wreck the strong .308 Win. rifle action. (Three grains of smouldered solid powder is still three grains of material, despite of it's gaseous form of existence).

Maximum allowed chamber pressure of .308 Win. factory-loaded cartridges is 3600 atmospheres. Case head stands 4000 atm. but the action may be hard to open and the empty shell is usually no more reloadable. Primer pocket may be enlarged and/or the primer blown. Pressure 4200 to 4500 atm. may blow the case head, and the action of many rifles stands as much pressure as the cartridge head; no more.

Severe hand and/or eye injuries of the shooter are possible if the action fails. Eye injuries, including the permanent loss of eyesight, are possible, when the case head fails. This depends on construction of firearm's action, but use of eye protection is always advisable when one is bustling with weaponry. Highest measured detonation pressure was 10 000 atmospheres. A pietzo-electric pressure gauge was broken and highest grade on the pressure scale was this 10 kilobars. A sturdy test-barrel of a German gun-proofing laboratory was wrecked, of course.

This disastrous test was repeated with another set of equipment for the sake of comparison. Pressures of first shots were slightly less than normal. It might be fifth or sixth shot, when the new test-shooting barrel blew up. Again a pressure gauge disintegrated and a scale told: 10 000 atmospheres! It was presumably just a fraction from whole horrible truth, because so called "wave pressure" of a detonation may exceed reading A HUNDRED THOUSAND ATMOSPHERES, when the explosive material is in gaseous form of existence, pre-heated and pressurized before explosion.

========continued at: http://guns.connect.fi/gow/QA1.html

Ain't the web great?

 

[LHB1]

Nando,
The solution to avoid "undercharging", "non-charging", "over-charging", or "double-charging" a case while using progressive press is to use a POWDER CHECK DIE AND LOOK AT IT FOR EVERY CASE/STROKE OF THE HANDLE!!! I have two Hornady LNL progressive presses. Both of them have an RCBS Powder Check Die installed and it has never failed as long as I look at it on every stroke of the press. Any variance of powder from normal volume is easily detected by the tell-tale rise of the Powder Check Die stem/flag.

Good shooting and be safe.
LB

 

[klw]

Most of my life I collected reloading equipment. Not many people interested in that so you could get just about anything and at a reasonable price. Hundreds of mould blocks. Dozens of presses. It was fun.

For most of that time I believe the standard myth that progressives didn't produce the best ammunition. I've changed my mind about that. No matter how careful I was I did manage to blow up a gun. Maybe it was my fault. Maybe it wasn't. BUT if I had been loading on a progressive a double charge would have been all but impossible for two reasons. First you can buy a double charge preventing die. I was actually using one on my turret press when I blew my gun up. Second you can tell at a glance what condition all the cases are when you look at the various die stations. You would know by looking, for example, if you had already put powder in your case.

A progressive has one more, rather subtle, safety features. It jiggles the hell out of everything. That's really good because it prevents powder buildups and jams in powder measures.

Remember how all Lyman powder measures have that little dumbbell on the side. That it to rap on the powder measure and help prevent powder buildups between the powder reservoir and the case. It works. On other brands of powder measures where I was weighing the thrown charges I've actually seen one very light charge followed by one big one.

So I think progressives are safer than other types of presses.

Incidentally I had maybe three dozen progressives when I collected reloading equipment. Used them all. Though I think that the Star (not made anymore) were by far the best, works of art really, my personal preference would be the RCBS Pro 2000. I own three of those and two of the RCBS Piggyback III's. Dillon's are ok but these RCBS machines use the APS strip primer system and that is, in my opinion, the best progressive primer system EVER!

 

[ChiefPilot]

As a follow up, I found a load I like at 12.0gr of WC820 behind a 110gr FMJ projectile. While all the loads worked, the cycling "felt" more positive with the 12gr load while still being a bit under the maximum listed load.

Thanks to everyone for their help and suggestions - I sure appreciate it!

 

[Ky Larry]

ChiefPilot, my Speer Reloading Manual #12 Lists the following data for their 110 gr 30 Carbine RN-FMJ bullet:

Starting load 11.4 gr AA#9 Vel 1739 FPS
Max Load 13.4 gr AA#9 Vel 1950 FPS
C.O.L. 1.680"