Just an idle thought here - I'm not planning to really do this, just wondered if anyone's heard about this...

What do you suppose might happen if one were to load pistols with really slow powder, like 4064 or 4350 in pistol cartridges like 38spl, 45acp, or even 44 mag?

I wouldn't do it out of fear of getting a detonation, but I just wondered if anyone had ever heard of this.

Just an idle thought here - I'm not planning to really do this, just wondered if anyone's heard about this...

What do you suppose might happen if one were to load pistols with really slow powder, like 4064 or 4350 in pistol cartridges like 38spl, 45acp, or even 44 mag?

I wouldn't do it out of fear of getting a detonation, but I just wondered if anyone had ever heard of this.

Haven't heard of anyone getting a detonation....have done what you suggest just to proove that a .45Colt case can actaully launch a bullet at deadly speed even with rifle powders (idea being, with a .45colt, even if you had to break down .308's to do ti). BUT it's terribly messy with unbuned powder, and there is a chance of missfire.

Not really a missfire...the primer lights off and the powder starts to burn, but for whatever reason, it fails to really combust. On a guess, at low presusre, the bullet moves...and in a revovler, it can move a LONG way before any real resistance from rifling. The increase in case volume can out pace the powder's rise in pressure....get a wad of "almost burned" powder. Stuff looks weird, it become translucent (the gray color is mostly a graphite coating) and cogs into a solid mass. Had t pick the powder mass out before driving the bullet back out of the barrel.

Smaller size cases would be worse.


So...yes, you can get slow rifle powders to make bullets exit a handgun, but once in awile it will leave a bullet stuck in the barrel with a wad of melted powder stuck behind it.

If you don't use enough H110/WW296 the same thing will happen, so it doesn't even need to be really slow powder, just not enough of the slow handgun powders.

Well, according to my 1990 IMR powder manual in the Rifle section, they list loads for the 44 Mag with a 240 grain bullet with a MAX load of 27 grs. compressed of IMR 4831 for 720 FPS out of a 22" barrel.

Is that a slow enough powder? :D

Regards

Well, according to my 1990 IMR powder manual in the Rifle section, they list loads for the 44 Mag with a 240 grain bullet with a MAX load of 27 grs. compressed of IMR 4831 for 720 FPS out of a 22" barrel.

Is that a slow enough powder? :D

Regards

Most rifles work differently. There isn't that long jump through the cylinder and forcing cone before finding the resistance of engravement...so there isn't that sudden big increase in volume before meeting resistance...and that resistance i what really gets the fire going in the powder (when using these slow powders).


Volume can increase so rapidly that it outpaces the rise in powder bruing...when that happens, it's not a missfire, but the fire kind of goes out (presure drops below the level whee these slow powders burn effectively).


If you just have to use medium to slow rifle powders in handgun cases in a REVOLVER, then will need the largest volume calibers (like the .44mag/.45colt) in order to have a fighting chance to fill that sudden volume increase. One problem with the smaller revolver rounds is that (1) they have such a small powder volume and (2) most are built on larger cylinders (like the .45acp revovles) which increases that long jump to engravment.

With rifles, the bullet only has a fraction of an ince to jump to engravement...and no open cylinder gap to further bleed off pressure just when it's needed...so they generally will puch the bullet out of the barrel.

Smokeless powder requires pressure to burn. Pressure in the barrel creates ignition and more pressure. Combustion curves are calculated around some complex physics which involve back pressures, chamber configuration (like a shouldered case), bore diameter, working velocities, etc.

You'd sabotage all the physics and chemistry engineered into a powder by the mfg. by choosing a powder for an application it's not designed to perform.

Rifle powder in a handgun won't burn efficiently. Handgun powder in a rifle and you're going to risk a catastrophic failure in the firearm.

Slowest powders I use are IMR 4227, and AAC 1680, both will turn in excellent accuracy in the .45 Colt, .480 Ruger, .357 Maximum, .375 Super Mag and others, but produce less velocity. Pistols such as the Contender and other single shots using wildcat cartridges often require slower mid-range rifle powders, such as IMR 4198 RL-7, H322, Bl-C2, H335, IMR and H 4895 and Varget. The 10 inch and 15 inch barrels seem to thrive on such powders, producing good velocities and accuracy.

I told Gmd3006 I would look at this thread awhile back, and didn’t get to it. Thanks to Nasty Jack for reviving it.

I think the old post by Contender pretty much tells the story. If you take a standard load of 24 grains of H110/296 over a 240 grain jacketed bullet, you have about 4720 ft-lbs of stored energy in the powder. The bullet will exit the muzzle of a 6.5” test barrel at 1430 fps with 1090 ft-lbs of energy or about 23.1% of what was in the powder. This number is the ballistic efficiency. 80.1% of the powder will have burned in the barrel, and the rest will fly out the muzzle when the bullet leaves.

Going to Contender’s load, 27 grains of IMR 4831 contains about 4800 ft-lbs of stored energy, but puts that same bullet out at only 720 fps and with 277 ft-lbs of energy from a much longer 22” barrel. This is a ballistic efficiency of not quite 5.8%, with an estimated 19.5% of the powder burned in the barrel, and the rest ejected or left in the bore. Quite a waste of powder.

No modeling changes I can enter into my software provides such lousy performance from that load with a 22” barrel as Contender reports without inserting unrealistic assumptions about start pressure and case volume. I think this is because the software won’t model a stalled burn, something that has been implicated in secondary pressure spikes. It apparently occurs when a bullet coasts down the tube so quickly and easily after being started by the initial pressure peak that it gets abnormally far ahead of the volume of gas evolving from the burning powder. If the barrel is long enough, the bullet velocity starts to drop due to friction overcoming what pressure there is. This drops pressure and temperature precipitously; far below the normal smooth decline of a powder burning pressure curve. That slows the powder burn further because slow powders depend heavily on pressure to keep up burning speed. Then forward inertia of the mass of burning powder catches it up to the bullet base and slams into it. This results in sudden local pressure rise at the bullet base, as the concentrating of heat generating combustion abruptly raises pressure and temperature throughout the mass. The mass can then detonate in the same way a gasoline engine knocks.

Texas gunsmith Charlie Sisk is able to reproduce this effect on demand (unlike undercharge detonation, which nobody seems to be able to produce on demand) and has intentionally blown muzzles off barrels in demonstrations. You can Google on the topic to find some of his forum postings. RSI’s web site also has information on it in their Pressure Trace instrument info. Thus far, I understand it has only been observed in barrels more than about 18” long. It takes some distance to get the pressure drop to occur.

In rifles, only a very light bullet is easy enough to push down the tube for the above problem to occur. The narrowing of a bottleneck case also provides a constriction of the gas flow that aids in building pressure. In a straight wall case, the wide diameter of the bullet relative to the volume of the case, means a large portion of the total surface area the powder builds pressure against is moving. It only has to move forward a few calibers to double the volume the powder is building pressure in. That and the lack of a gas constriction make it hard for a slow powder to build pressure.

While you don’t normally see barrels in pistols that are long enough to cause a secondary pressure spike, some rifles chambered for pistol cartridges have them. Use of slow powders may be dangerous in these guns. In revolvers, using a slow rifle powder will also likely cause the problem that occurs with small loads of H110/296, where pressure drop due to gas bleeding out of the barrel/cylinder gap drops pressure enough to fizzle the burn and leaves the bullet stuck in the barrel.

High cost, poor performance, potential hazards. All yours with slow rifle powders in handgun cartridges.