IMR 4831 in .223 Rem bolt gun at 100 yards works well as a target load.

[mikeAB]

WARNING: This load is way too slow for hunting, and may not have the pressure needed to work an impingement gas system reliably.
IMR 4831 in .223 Rem bolt gun at 100 yards works well as a target load.
Test:
All loads charged with 1.9cc ~= 25.5 Gr IMR 4831 powder.
All loads fitted with Remington 7½ bench rest primers.
First Load:
Sierra 53 Gr Match Kings set 1.880” Head to Ogive.
Noslor cases on there 17th loading.
Second Load:
Same as first, except Sierra 69 Gr Match Kings set 1.900” Head to Ogive.
Third Load:
Hornady V-Max 40 Gr set 1.880'' Head to Ogive.
Lake City cases on their tenth loading.
Fourth Load:
Same as third, except Hornady V-Max 50 Gr set 1.900” Head to Ogive.

Test conditions/equipment:
Weather: wind direction shifted constantly no steady state, wind speed 5-10 gust to 15, 80 F, slightly humid, light clouds, no haze, visibility excellent.
Rifle: Savage 112 BVSS, 1:9, 26” medium barrel, fired off Caldwell mounted on a heavy shooting table.
Wind flags set every 25 yards.

At 100 yards each load tested with eight | three shot groups.
Results at 100 yards.
First Load gave < 1” groups.
Second Load gave == 3/4” groups.
Third Load gave == 3/4” groups.
Fourth Load gave == 3/4” groups.

At 200 yards each load tested with three | three shot groups.
Results at 200 yards.

First Load gave < 3” groups.
Second Load gave < 4” groups.
Third Load gave < 3”
I did not test the fourth load at 200 yards.
Point of impact was 16” below point of aim at 200 yards.
During cleaning I found no undurned powder.
Barrel had more soot in it at cleaning than usual, but it never got hot.
These were not compressed loads, I would call them snug loads as the bullets snug into the powder but did not compress it. Always look in the case to make sure you have a full charge.
The IMR 4831 (in these cases) came up to the bottom of the case neck.
If you load .223 rem or similar case with IMR 4831 keep in mind that it is BIG STICK powder and may jam up in your powder tube.
I simply went slowly when it came to the powder charging stroke so the powder would poor in slowly and not drop in all at once and possibly jam up in the powder tube.

[Jimro]

Check your barrel for internal ringing.

Jimro

[GeauxTide]

Would you use a powder that slow in a case that small?? I'd love to hear what Unclenick's thoughts are.

[Economist]

Any chronograph data?

[mikeAB]

Jimro.
Thank you for your concern.
I visually inspected every powder through and made sure I had a full charge.
After firing I inspected every case and primer for over pressure signs and found none.
I know of the worries of shooting cast bullets with light loads of IMR 4831 set with some type of filler.
If you have any data on full case charges of IMR 4831 with jacketed bullets suspected of causing chamber ringing please let me know.
Thank you.

[sawdustdad]

There is published data for reduced charges in rifle cartridges. H4895 and Trail Boss come to mind. Hodgdon has published loading data for both.

I've used/experimented with both. You have a range of reduced loads with H4895, but can only go so low. I think it's about 2200fps with H4895 in 30-06. To go REALLY low, use Trail Boss. About 1300fps with a 165g bullet. Fun to shoot. Recoil on par with .223 out of a typical AR.

Highly advised for introducing new shooters who may be recoil sensitive.

These are both proven and safe approaches to loading down rifle cartridges.

[Unclenick]

Originally Posted by mikeAB

After firing I inspected every case and primer for over pressure signs and found none.

If you read the article I linked to in your other thread, you will learn that there are no pressure signs on or in the case or primer when ringing pressure is created down the barrel near the bullet base due to using a powder too slow for the sectional density of the bullet. It's strictly local to that place. The only way to tell you are getting into trouble with a load like this is either to use a bore scope to look for the ringing or equip the gun with a pressure measuring system that uses strain gauges, specifically. When the barrel ringing force slams the sides of the barrel down by the bullet base, that sets up a surface wave that returns to the chamber area and momentarily expands its diameter which registers on the gauge the same way actual pressure underneath the portion of the chamber it is glued to would do. But that's not where the pressure actually occurs, which is why you don't get pressure signs on the case. It's also why neither a copper crusher nor a piezo transducer pressure gun will register the event.

Texas gunsmith Charlie Sisk has blown the muzzles off .338's on command with a particularly egregious example of a load of powder too slow for the bullet SD. He used to have the pictures up on another board, but stopped hosting them on his site. You could email him and ask about it. But again, the cases all looked just fine when it happened.

[thallub]

Just looked at the old IMR Handloader's Guide. It gives 25 grains (compressed) of IMR 4831 a muzzle velocity of 2,375 fps

Looked at the wrong column. 26 grains of IMR 4831, a Remington case and a 55 grain Hornady spire point bullet gives 2,415 fps.

[thallub]

mikeAB is not making reduced loads. He is using a case full of slow burning powder. There's a difference.

[GeauxTide]

I'd listen to Unclenick. In my 40 years of reloading, I've not come across a more knowledgeable individual. FWIW, 25 grains of H-4895 is what I load for 55gr bullets in that caliber.

[thallub]

What does case full have to do with anything?

It has to do with a handloading guide published by the IMR Powder Company. Powder companies do a lot of research and testing prior to putting their recommendations in print.

BTW: i use 25 grains of IMR 3031 and a US military case in most of my 55 grain .223 loads.

[Unclenick]

They do, but they do it on SAAMI standard test equipment which is not strain gauge based and does not show the secondary spikes. Again, read the article I linked to and look around the site. It shows some commercial loads that produce terrible secondary spikes because the equipment they use is looking only at the pressure inside and not at the effect on the surface of the steel that a strain gauge does.

The reason the case being full makes no difference to this problem is it occurs when the bullet is well down the barrel, and not when it is still in the case. There is therefore all the bore volume behind the bullet (expansion) as well as the space in the case involved. Again, this is not an in-chamber phenomenon. If it were, the brass would have pressure signs.

With kind permission from Jim Ristow to share his images, here's a trace from a lot of commercial ball ammo made by Winchester using a spherical powder too slow for the bullet weight:

[Jimro]

MikeAB,

Unclenick has more knowledge than I when it comes to reloading, so if what I write here is wrong he'll correct me.

There are two dangers to using a slow powder. Secondary Explosion in the brass/chamber and Secondary Pressure Spike in the barrel. Here is how I understand the theory behind them, where chemistry, physics, and materials science all collide.

These have to do with the way concussive (pressure) waves travel through gas as a medium, and the chemistry of nitrocellulose.

Nitrocellulose is an explosive, but in the ammunition realm we don't want it to detonate (explode), we want it to deflagrate (burn). An explosion (detonation) is what happens then the activation energy triggers all the molecules to go from solid to gas at roughly the same time. Burning (deflagration) happens when only the surface of the substance is transitioning from solid to gaseous state.

To get a detonation you need heat and pressure. This is why you can cook with C4 by lighting it on fire, but make it blow up with a blasting cap. The powder in your ammunition is lit off by the primer, which is designed to cause a deflagration, not a detonation. But once the powder starts burning, pressure starts rising, and the bullet will start going down the bore. You now have a dynamic system, pressure being created by the burning, and pressure being let off by the bullet going down the bore creating more volume.

The bullet has to overcome friction, and if you use a powder on the very slow side the burn retardants in the mix may cause a situation where the hot gasses pushing those slow burning powder kernels down the bore suddenly run into the back of the bullet which causes a localized pressure spike, which causes those powder kernels to detonate, which is evidenced by internal ringing in the bore and a Secondary Pressure Spike on the pressure trace equipment.

The other condition, a detonation, is caused when there isn't enough case fill and the bullet gets slowed down earlier in the barrel, and a few kernels detonate sending a shockwave back into the chamber area causing a detonation of the powder still burning there. This is the Secondary Explosive Event, or a "kaboom" incident.

Because you have such a high case fill, a SEE is unlikely, but a SPS seems likely. You'll need to check with a borescope for ringing.

Jimro

[T. O'Heir]

"...1.9cc..." CC's are a metric unit of liquid volume. 'CC' means Cubic Centimeter. CC's have nothing whatever to do with reloading. If you're using a Lee scoop as a powder measure, throw it away and use a scale.
That being said, just because Hodgdon didn't test IMR4831 for the data on their site, doesn't mean the powder is no good. Thallub's "a handloading guide published by the IMR Powder Company(owned by Hodgdon) and data on Reloader's Nest(verified) both show 50 and 55 grain .223 loads using 26 grains of IMR4831. The latter is the same guy using 26 for 3 different bullet weights though.
"...25 grains of IMR 3031..." Over current max, but only by .4 grains. snicker. Filling or not filling the case is irrelevant.

[thallub]

Thanks Unclenick: For the graph. Is that the graph of the Winchester round that destroyed several M4 police rifles?

Yep, i know all about explosives. Spent a career in the US Army EOD progam, retiring in 1979. Worked an additional 30 years as a civilian EOD tech/firing range advisor/ammunition advisor. Advised foreign militaries in the areas of ammunition, EOD and management of firing ranges.

Have also spent a lot of time around artillery folks including one well known ballistician. That ballistician is old and in great demand: He commands big bucks.

i'm aware of a few cases where artillery tubes blew up because of pressure excursions when firing low charges. US Army ballisticians have been able to replicate that. i'm not sure that extrapolates to small arms. Why are we not hearing of guns blowing up when pressure excursions exceed 100,000 psi?

i've been reloading since 1953 when i inherited several guns and their reloading equipment from an uncle who was killed in a logging accident. Never got into reduced loads. A few times i have loaded full charges of slow burning powder with no problems.

My ballistician acquaintence is currently in the middle east when he gets back i will ask him about this one.

25 grains of IMR 3031..." Over current max, but only by .4 grains. snicker.

One of the numerous reasons i refuse to own a current reloading manual.

[Unclenick]

CC's are fine if you know the bulk density conversion to grains (VMD number). The problem is you can't get too comfortable with published VMD's. A perusal of the Accurate web site shows that for some powders this number varies by over 11.2% (±5.6%) from lot to lot. The best number they have varies about 4% (±2%). So you still have to cross-check with a scale if you want to know exactly what you are throwing. If you have a load low enough that you have the 6% headroom, then that becomes optional.

Jimro is right on secondary explosion effect (S.E.E.), which is usually observed when small amounts of powder are used that fill the case poorly. On the secondary pressure spike happening down in the barrel, though, no detonation is involved. When detonation occurs you see signs of shattering in the metal. When Charlie Sisk blew barrels off the .338's, it took, I was told it took about a dozen rounds, and the ringing just gradually battered the bore out until it fatigued and broke off. This is caused entirely by powder mass momentum slamming into the base of a stalled or slow moving bullet. Hatcher demonstrated the principle by casting a 4 inch obstruction into a barrel and firing a charged cartridge case with no bullet in the gun. This bulged the barrel right in the middle of the 4" casting. In other words, there was a hand-off of momentum from the molecular rear-end collision to the soft lead in the cast obstruction.

Thallub,

Yes, reduced charges do occasionally blow up small arms. It's just harder to replicate with the smaller guns due to statistically less significant quantities of powder being involved.

One thing to know about those secondary spikes registering on a strain gauge is that they always disappear if you either go to a faster powder or you go to a heavy enough bullet that doesn't start down the barrel as quickly. Unfortunately, buying the equipment is the only way to know for sure if you are getting them or not with a particular recipe.

I don't know if that was same ammo in the blowups or not?