Powder types - need a little education...

[DHart]

I'm a total novice when it comes to powders... and I have begun a quest to try to find pistol caliber factory ammo (.357mag, .44mag and .45 Colt) which will perform better in longer barrels (like a 16.5" carbine) than they do in pistols.

I understand that cartridges which use slower burning powder tend to be able to make better use of longer barrels and do improve in speed and energy.

I'm wondering if I can determine slower from faster burning powders by sight or by weighing the charge that I find in a cartridge. I know that some pistol cartridges employ very fast burning powder (because the cartridge is intended for a short barrel weapon) and when fired from a rifle, may actually lose a little performance.

I have read that some pistol ammo makers economize by using a faster burning powder because it requires a smaller (therefore less costly) charge. If they were to use a slower burning powder (which would be more useful in longer barrels), there would be a larger (therefore more costly) charge... is this generally true?

•Does a slower burning powder require a heavier charge than faster burning powder for similar power level? For example if I open a factory made cartridge and find a powder weight that is significantly heavier than a powder weight in a competing brand of cartridge, would it be safe to assume that the cartridge with the heavier powder weight is using slow burning powder which would be more suitable for use in a carbine than the cartridge which uses a fast burning powder?

 

[Delmar]

DHart-kind of a hard thing to do. The reason being the commercial ammo makers are using cannister grade powders, which is something not available to us retail folk as a general rule.

However, slower burning powders generally require a heavier charge than something fast burning to achieve a similar pressure level. It does seem to have something to do with the case capacity as well.

 

[Kruzr]

A link listing fastest to slowest powders: (from Sierra)

http://www.egpworld.com/RELOADING/POWDERS/1/BURN_RATES.htm

 

[stans]

I understand that cartridges which use slower burning powder tend to be able to make better use of longer barrels and do improve in speed and energy.

This is generally true. Faster burning powders will fully combust and generate peak pressures in shorter barrels. The 38 Special is a pretty good example. There is a pretty hefty increase in velocity in the 38 Special when going from a 2 inch to a 4 inch barrel. There is about half again increase when going from a 4 inch barrel to a 6 inch barrel.

Slow burning powders do require more barrel length for complete combustion. The 357 magnum really suffers a velocity loss from a 2 inch barrel, it performs much better from a 4 inch barrel, and best performance in a handgun is going to come from 6 to 8 inch barrels.

I'm wondering if I can determine slower from faster burning powders by sight or by weighing the charge that I find in a cartridge.

Don't even think about it. Factories do not use the same powders available to us.

I have read that some pistol ammo makers economize by using a faster burning powder because it requires a smaller (therefore less costly) charge. If they were to use a slower burning powder (which would be more useful in longer barrels), there would be a larger (therefore more costly) charge... is this generally true?

I can't speak for the ammo factories, but handloaders have a history of selecting the fastest burning powder for a given use and it does end up costing less per round because a pound of powder will make up more cartridges. I would expect ammo companies put safety first, since one law suite would wipe out any savings made by using a powder that was a little too fast for the intended use.

•Does a slower burning powder require a heavier charge than faster burning powder for similar power level? For example if I open a factory made cartridge and find a powder weight that is significantly heavier than a powder weight in a competing brand of cartridge, would it be safe to assume that the cartridge with the heavier powder weight is using slow burning powder which would be more suitable for use in a carbine than the cartridge which uses a fast burning powder?

Well, there again, don't make assumptions. Generally speaking, the slower the powder, the greater the quantity required for a given operating pressure and velocity.

 

[WhoKnowsWho]

and I have begun a quest to try to find pistol caliber factory ammo (.357mag, .44mag and .45 Colt)

The new Lyman reloading manual has rifle loading data specific for those three calibers. I would assume those are more specialized for longer barrels, since the data is seperate from the normal handgun data.

Oh wait, just noticed you said factory ammo, well, good luck, much better options when you handload!

 

[DHart]

I understand the wonderful benefits of "rolling your own" in terms of tailoring each cartridge excatly for the task at hand... that is cool. At present I don't handload and am unable to make time for it. And my interest is specifically pistol caliber defense loads to be used in carbine length rifles... for defense against two legged evil doers... and for this purpose, I would prefer to stick with factory ammo, even though that really narrows the options. Thanks for the info.

 

[Mal H]

For the limited purpose you are trying to achieve (higher velocity in a long barrel using handgun rounds), I think your premise is probably correct. The heavier charge of powder in similar cases/calibers will generally be a slower burning powder. However, there are so many variables involved that it is impossible to say that will always be the case.

Your best bet for finding out what you want is to buy or borrow a chronograph and get some real velocity figures for the various factory rounds. That is a much more precise method to find the round with the highest vel out of a carbine barrel.

 

[DHart]

Mal... I'm starting to realize that I'm really going to need to chronograph a variety of the rounds I'm considering... (.357mag, .45Colt, .44mag) I want to find loads in these pistol calibers which will moderately increase in velocity when fired from a 16" Trapper, but not so much that the bullet performance in the target is severely compromised (too much expansion too early). When and if I get that done, I'll post my results.

 

[1911Tuner]

Velocity

Howdy DHart,

Before you jump in too deep, understand that it's easy to get wrapped up
in the "Velocity Game". i.e. "If the book says that I'm supposed to get
1500 fps from this cartridge, and I'm only getting 1425, that's a bad thing...right? It won't expand/penetrate/provide stopping power, etc."
Nothing could be further from the truth. The target will never know the difference.

Keep a few things in mind for your carbines.

The revolver cartridge was loaded with a revolver barrel in mind. The bullet
was designed to perform from that barrel length and velocity level. When
you shoot the round in a rifle, you are most likely going to get a velocity increase that will enhance expansion and possibly limit penetration.

The way to make sure of decent expansion AND take care of the penetration issue is to stick with bullet weights that are "standard " for the caliber. .44 mag/240....357/158....41 mag/210 and so on. The lighter bullets will be faster and expand more violently...and may fragment without
penetrating as far as you'd like.

The magnum rounds will give a proportionally greater velocity increase
than their "Special" counterparts, due to their slower-burning powders
and the fact that both the .38 and .44 Special are downloaded from their potential quite a bit. The factories have to do that because of the large numbers of revolvers still in service that are approaching the century mark.

A 16-18 inch barrel shooting a .44 Special round will hit plenty hard out to
about 50-60 yards farther than the same round in a 4-inch revolver barrel...
and the .44 Special revolvers have put a lotta men down for the count.
In .44 Special, I'd go with the 200-grain Silvertip and be confident with it.
In.357 magnum, the 145-grain Silvertip or the Speer/CCI 146-grain hollowpoint is a good one. More penetration comes with the heavier
hollowpoint bullets in magnum loadings...and even more is available with the jacketed soft-points.

 

[Archie]

DHart... it's simpler than you think.

First of all: Powder burning rate varies with the weight of the bullet. Barrel length has nothing to do with selection of burn rate.

That probably seems counter intuitive, but it's true. I've loaded ammo far too long and chronographed too many loads and load variations to be unsure.



Second: Buy the premium self-defense ammo you would buy for a handgun. The fastest round in a short barrel will be the fastest round in a long barrel. (There are some anomolies with this, but it's true enough to bet on.)

Ammo makers use the powder that will function the gun for which the ammo is intended. Auto pistol calibers have to generate "more than XXX and less than YYY psi" to make the gun work and not blow it up. Revolvers are a bit different, but you mentioned 45 Colt. 45 Colt is loaded pretty light so no one blows up "Grampa's gun", a blackpowder frame revolver......

The answer to your problem is (I say again) Buy the premium self-defense ammo you would buy for a handgun.

 

[Deavis]

First of all: Powder burning rate varies with the weight of the bullet. Barrel length has nothing to do with selection of burn rate.

That is an interesting statement. I'm not sure I am completely qualified but I think that you are making a generalization that is true but not for the reason you give. Maybe some of the more experienced guys can chime in here and help out if I'm wrong. I'm thinking out loud here so correct as necessary, this is by no means a "you are wrong rebuttal" I'm just trying to think it through logically. So here goes...

I think the correct thing to say is that the burn rate of a powder depends on the chamber conditions when the round is fired. If I am correct in my understanding of smokeless powder, its burn rate will be based, mainly, on the temperature, pressure of the chamber, and composition of the powder. Smokeless powder undergoes a slow explosion called deflagration and the intensity of its burn is largely dependent on pressure under which it burns. Being under pressure during burn is one of the reasons that the powder is efficient and smokeless. That is why smokeless containers are purposefully built weakly; the container will split before the pressure becomes so intense that the deflagration becomes detonation.

Now, the reason that bullet weight affects the burn rate of the powder is because the bullet has a direct affect on the pressure seen by the powder as it burns. This is because the pressure in the chamber during ignition is not constant. A direct consequence of the bullet leaving the cartridge is that as it travels down the bore, the relative chamber size, as seen by the powder, is expanding. A heavier bullet will take more time to leave the chamber and the powder will therefore be at or reach a higher pressure for a longer period of time until it can no longer supply pressure fast enough to fill the volume being exposed by the accelerating bullet.

You can imagine that if the bullet was very light it would exit the chamber and barrel very quickly leaving nothing for the powder to burn against. You would see the color of the flame front would most likely be orange as the powder burned off inefficiently. Most likely nice flecks of burning powder would accompany this flame front as they tried to escape their high-pressure prison. Conversely, if the bullet were so heavy that the powder lacked sufficient power to expel it from the chamber the pressure would rise dramatically and eventually rupture the weakest part of the barrel.

The issue then becomes a matter of how fast can the powder build pressure behind the bullet, how fast the bullet leaves the barrel, and how quickly the weapon cycles. I'm willing to bet that the bullet usually leaves the barrel faster than the powder can build or maintain pressure in a handgun. In addition, I would bet that the pressure required to overcome the initial inertia of the bullet is greater than the pressure required to overcome the friction of the lands after their initial impression has been made on the bullet. That does not mean that the bullet is no longer being propelled after the initial oomph into the barrel, it just means that its acceleration would be negative relative to the first part of its travel as it goes down the barrel and then exits the gun.

Thus, the delay in the weapon opening its breech must be just long enough that the bullet has been expelled and a large part of the pressure has been vented via the end of the barrel. Otherwise it would expose the operator to unnecessary risk and of course this means that your slide/spring combination must make sure that they have more inertia than the bullet! You can imagine an infinitely light slide being propelled backwards while the bullet sits happily in the chamber providing the wall for the pressure to build as the cartridge loosens and goes backwards with the slide.

That is how I came to the conclusion that it is the chamber conditions that affect the burn rate of the powder being used and not simply the weight of the bullet that you are using. I would be willing to bet that changing the profile of a bullet and the barrel friction would have an affect of the burn rate of the powder as they could potentially increase the amount of time it spends burning in its preferred environment, i.e. under "max" pressure. I wonder if it is a semi-linear change or a logarithmic change with pressure?

What do you guys think? Is the analysis inline?

 

[Delmar]

Powder does not burn at a linear rate-it depends on the chamber shape, diameter, bullet weight and style (how much area of the bullet engages the rifling), the type of primer (standard or magnum), the loaded bullet's distance from the lands of the rifling (free bore), and the deterrent coating of the powder, not to mention pressure.

All have an effect, and one of the reasons why you should always use the components listed in your loading manual, especially when getting close to max.

Take for example the difference between a bolt action 308 and a 260 Remington. Just by looking at their dimensions, you would think the 260, with the same sized case and smaller bore that it would prefer a slightly faster powder. However, the opposite is true.

If you further toss in a mechansim dependent on a proper powder burn, time then comes into play, such as in an autoloading pistol. As you correctly state, the action needs to stay sealed until the bullet has left the barrel in order for it to be efficient and safe for the shooter.

 

[The_Antibubba]

The cost of handloading

...for defense against two-legged evildoers...

I understand what you're trying to do, because i have a Rossi carbine for the same purpose. But if you ever do have to shoot that particular animal, you do NOT want to have to face a prosecutor who will throw your"handmade extra strong mankiller bullets" in your face!

Look at the heavier weight Hunting rounds. There are 180 and 200 gr .357s. The difficulty will be in finding one that's safe for a tubular magazine (FP or HP). When you find one you like, that is when you develop a handload that matches it, so you can shoot many hundreds of identical, but much cheaper, practice rounds. Those premium pounds are costly.

But not as costly as a lawyer to keep you out of prison!

 

[DHart]

YEP... my reason for sticking with factory loads is to circumvent that potential legal issue. You make a great point about trying to match the factory load with reloads to facilitate less expensive practice! Awesome.

I now have a chrony f1, so at least I can see what the various rounds are actually doing out of my carbines. So far, I've only had my 20" Marlins as test rifles, but I have two 16" Trappers on the way. These Trappers will be my back up defense rifles right behind my Mossberg 500 12 ga. "Persuader".

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Winchester/Miroku '92 Ltd. 16" Trapper - .45 Colt

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Legacy/Rossi '92 16" Trapper Ltd. Ed. - .454 Casull

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Out of my Marlin 1894SS .44mag I tested this .44special load:

Winchester Super X - chrony ballistics from Marlin 1894SS with 20" barrel
X44STHPS2 44 Special 200 SilvertipHP Velocity >>>893
X44STHPS2 44 Special 200 SilvertipHP Energy >>>354

With the 20" barrel, the performance of this round was slightly less than Winchester's published data for the ammo when fired from a pistol. Not sure whether the velocity might increase slightly when fired from the 16" Trapper, but we'll soon see! In any event, while this may be a decent defense load, and certainly is very tame to shoot, there must be something which packs a better punch without having to go to full power .44mag in this particular rifle. Someone mentioned that the WW .44mag Silvertip load was a moderate load by .44mag standards, so I'm going to try soome of that when I can find a box. Being an analytical kind of guy and a gun lover... this is fun stuff!

 

[tex_n_cal]

Factory ammo can vary a lot from its published data. I once had a batch of .25-06 that chrono'd a good 300 fps under factory ballistics. I would try shooting some of out a revo, then the same box out of a rifle, before judging the velocity change.

When I first got into handloading, there was a well known gunwriter who swore that the .30-30 would never be accurate out of pistol length barrels, it had too much case capacity. About 15 years later the same guy wrote a different article, stating that the .30-30 gave "excelent accuracy" in single shot pistols! I guess maybe he had a bad barrel the first time around

I have shot a bunch of .44 mag loads with both W296, and Lil'gun out of revolvers, Contenders, and carbines. Generally, those powders are the slowest practical powders for the cartridge, as they are slightly compressed in full power loads. The load that goes 1400 fps out of a S&W will go 200 fps faster out of a 10" Contender with solid breech, and another 100 fps faster out of a 18" carbine. The same powders that gave the best accuracy out of a carbine also gave the best accuracy out of a revo. I don't own a snubby .44, but I sorta expect that flash and blast would be ugly with 296, but it should still shoot well.

Going in the opposite direction, the best loads for my Ruger #1 .22-250 also shoot great in my XP-100R in the same caliber. You'd think that 14" pistol barrel would want different powder, but it doesn't.

I guess this experience leads me to say that powder selection is more a matter of cartridge and bullet, than barrel length.

 

[DHart]

Thanks Tex... there are certainly a lot of variables. And the fact that factory ammo uses powders which are otherwise unavailable or identifiable doesn't help much. I know that with "rolling your own" you can achieve a wide range of objectives. For me, I'm choosing to stick with factory loads at present, for a variety of reasons. I am having a good time chronographing different loads.. this is fun stuff for a "gun geek" like me.