Reduced loads, minimum loads and detonation in handguns

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Sonnytoo

Blackhawk
Joined
Aug 4, 2007
Messages
631
Note that ALL of this info was gathered from several long articles in my 1981 NRA book of HANDLOADING. Good articles; good book. Some of this material is also directed toward rifle loads and forum members should be aware of this fact.
Reduced Loads article by WM. C. Davis, JR.
Powders suitable for full-charge loads are usually of large granulation and have deterrent coating on the grain's outer surface to achieve better velocity-pressure relationships in max loads.
Since smokeless powder burns at a rate which is strongly dependent on pressure, reduced loads which use powders suitable for full-charge loads often do not burn completely and produce poor results. Using powders of finer granulation, designed for faster burning, result in more consistent loads. "Minimum loads in rifles and handguns require the use of lubricated lead bullets and fast-burning pistol or shotgun powders."
Using rifle cartridges with large powder capacity and small-diameter bullets, less than .35 caliber, require special caution with reduced loads.
"For reasons not completely understood, reduced loads of slow-burning deterrent-coated powders in such rifle cartridges will, on rare occasions, develop destructively excessive chamber pressures when fired." However, the author then notes that Hercules ran exhaustive tests with severely reduced loads in rifles, using slow-burning powders, and was unable to blow up any rifles, despite the most severe tests that could be conceived. This led to rather convincing evidence that such blowups were more likely the result of double charges of powder.
For Handguns only:
Two basic things to watch out for in assembling loads with reduced or light powder charges. Certainly, the first is to be aware of the danger of double or multiple charges. The second point is to avoid the use of jacketed bullets. Use only lubricated cast bullets due to their greatly decreased friction in traveling down the bore.
"WW296 is a handgun powder that should be used in the charges which are specifically recommended and never in reduced loads." And we are also familiar with H110 having specific caveats against using reduced loads. Problems associated with the use of these powders may lead (at least) to the primer pressure pushing the bullet into the barrel forcing cone, leaving a large chunk of unburned powder sitting directly behind the bullet.
The author recommends, for full-charge factory loads, such powders as Blue Dot, 2400, SR-4756, IMR-4227, WW 296 or H110. (I am aware that there have been some warnings against using Blue Dot in handgun loads, but I am NOT aware of the specific warnings. Perhaps one of our readers can help out here.)
"Powders for reduced loads should be easily ignited by the primer, burn completely, and be of low bulk density to occupy as much space as possible in the cartridge case." He recommends well-known double-base powders such as Unique and 2400 for easy ignition and (usually) good results. For handgun less-powerful loads in the .357, .41 and .44 Magnum cartridges, suitable powders are Unique, PB, WW 630 and HS 6.
"For light targe loads, using lead bullets, Bullseye, 700X, WW 231, and HP-38 are available."
He notes that a large amount of air space in reduced loads is detrimental to their performance and suggests that one way to solve this problem is by the careful use of fibrous filler materials. There have been problems, however, such as "ring-bulges" occurring with this method.
An alternative procedure, which has often been mentioned by other posters on this site, is to elevate the gun's muzzle just before aiming at the target and firing the shot, thereby assuring that the powder is always positioned at the head of the cartridge case.
The author doesn't always distinguish between powders recommended for handguns versus powders more specifically used in rifles. Use this information at your own risk..or buy the book and make your own determination.
Another related article in this book, MINIMUM LOADS IN HANDGUNS, by William Dresser, stresses the use of normal-weight-for-caliber wadcutters to minimize airspace within the case, as well as the nearly universal use of Bullseye pistol powder due to its ease of ignition. His article concerns using absolute minimum loadings, for "basement" target practice, which is really not the point of my post.
I offer this material as I did find it to be very interesting, and may answer some concerns of forum members. I understand that this information may seem dated (1981) and that more recent information may offer newer or better methods. Please use this material at your own risk.
Sonnytoo
 

Jimbo357mag

Hawkeye
Joined
Feb 22, 2007
Messages
10,103
Getting good shooting, accurate, and reliable reduced loads is an art. I have had good luck reducing 357mag and 44mag down by 10% - 20% from Max using AA #9 and Blue Dot with standard weight bullets. For 20% or more reduction from Max I use Universal or HP-38. :D

...Jimbo
 

454PB

Bearcat
Joined
Mar 30, 2005
Messages
48
Everything in this article is still true today.

Those of us that "experiment" with hard to ignite powders or very light loads have to be especially vigilant.

I've pounded a few stuck bullets out of barrels, and stuck cases out of chambers. Every time it happens, it's a learning experience.
 

Snake45

Hawkeye
Joined
Mar 14, 2009
Messages
6,064
Jimbo357mag":jv09iwaq said:
For 20% or more reduction from Max I use Universal or HP-38. :D

...Jimbo
Jimbo, dunno if you know this, but HP-38 and WW 231 are exactly the same powder. This is useful to know if you can find one powder but not the other, or load data for one but not the other, or a much better price on one than the other, etc.
 

Jimbo357mag

Hawkeye
Joined
Feb 22, 2007
Messages
10,103
Yep, the new stuff is the same. There was probably a difference a few years ago but not anymore. The same can be said for H-110 and W-296. :D

...Jimbo
 

dmazur

Bearcat
Joined
Oct 31, 2007
Messages
62
I found an article in an old Hodgdon 2007 Annual Manual, titled "Trail Boss - It's Not Just for Cowboy Action Shooting". The author has written several pages that explain reduced loads, using Trail Boss, for pistol as well as rifle cartridges.

This is a low bulk density powder that appears to be excellent for developing light loads without the dangers usually associated with light loads.

In addition to having little/no concern about detonation, this powder isn't position sensitive (makes no difference if you point muzzle up or down) even with less than full case loads.

So, it might be something to review, for those who want to develop "powder puff" loads...
 

bearing01

Bearcat
Joined
Sep 15, 2009
Messages
71
How common is it for guns to get blown up on factory ammo due to double powder charge? Anyone here see that happen?
 

Snake45

Hawkeye
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Mar 14, 2009
Messages
6,064
bearing01":3vlmc3ij said:
How common is it for guns to get blown up on factory ammo due to double powder charge? Anyone here see that happen?
I don't believe that in 35 years I've ever heard of one documented case.

While I'm posting, I think "detonation" of small charges of fast powder is also a myth. Last I heard, no one had ever been able to make it happen under controlled (laboratory) conditions. I believe the current thinking is that "detonation" blowups are actually double or triple charges.
 

Yosemite Sam

Hunter
Joined
Mar 18, 2002
Messages
2,113
Snake45":va2hl59e said:
bearing01":va2hl59e said:
How common is it for guns to get blown up on factory ammo due to double powder charge? Anyone here see that happen?
I don't believe that in 35 years I've ever heard of one documented case.

While I'm posting, I think "detonation" of small charges of fast powder is also a myth. Last I heard, no one had ever been able to make it happen under controlled (laboratory) conditions. I believe the current thinking is that "detonation" blowups are actually double or triple charges.
That's my understanding, and what is becoming the "conventional wisdom" on several sites that I read. However, Driftwood Johnson makes a good argument for what might be a detonation scenario here.

I'm tending to think it has more to do with burn characteristics of specific powders, which also happen to be powders that it is easy to double charge.

In any case, it's a situation where choosing a proper charge (powder type and weight), and exercising care when loading should prevent issues. My only "concern" about the issue is academic, once I learned that I can make light loads when using the appropriate powder.

And yes, Trail Boss is great for light loads. A "just above minimum" load in .45 Colt with even a 250gr bullet is a very soft shooting round. I don't have a chrony, so can't tell you the velocity. My only complaints with this powder are that it doesn't flow through my Lee Auto Disk measure very well, and seems to stain brass badly.

I'm also finding that HP-38/W231 works really well in light-mid loads in both .45 Colt and .44 Special. This is my current favorite powder.

-- Sam
 

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