AA #7 takes a powder

[theHeretic]

A friend recently gave me some of his supplies [he stopped up reloading about 6 years ago]. Among the items was about half a pound of Accurate No. 7. The powder was in the original bottle with the original sealing foam disk loose but in place. Since I normally load 9x19 and 38’s using Unique, I decided to try to develop a practice load for the 38’s using this powder.

After some research I decided to try 6.0 grains under a 115 grain lead with CCI 500 primers and loaded a total of 6 cartages for a test.

The first round fired with a rather dull report and a light recoil striking the target quite low. The second produced a pop with no recoil and nothing on the target. At this point I stopped to inspect, opening the cylinder and checking the barrel. Sure enough the bullet was lodged firmly. I assumed that I had not charged that case [only happened to me once before] and returned to my loading bench to drive the bullet out. While there I weighed the four remaining cases to assure myself that I had charged each case.

I returned to my range [about 30 yards from my loading bench] and tried the third round. Same pop and no recoil. This time I did not open the action until I was back indoors at the bench. I found the bullet lodged in the barrel with the powder charge packed behind it in the forcing cone.

I know that No. 7 has a slower burn rate than Unique, but when I ignited a 10 grain sample in a test dish, it burned at about twice the rate as shredded paper.

Needless to say, my grass got a little fertilizer. My question is, What went wrong? I noticed no smell or texture abnormalities. The powder seemed to be quite dry and stored properly and, based on the price tag on the bottle, could not have been older than 7 or 8 years old.

Any thoughts would be appreciated.

 

[bender]

weird.

I had a pound of Accurate #5 and a pound of #2 both over 15 years old... and for the last 10 years they've been in my hot Texas garage... I recently shot up all the #5, no problems.

Haven't tried the old #2 yet

I also have a 15 year old pound of Win 231, which I have been using without problems... however, it looks funny... kind of a rust color on some of it. Works good, though. I'm gonna dump it out anyway.

In fact, since I stopped reloading 15 years ago.... and now have started it up again... all the powders I am using are 15 years old, and all are working fine: 2400, Unique, Blue Dot, 4895, and several others.

Don't know why yours went bad.....

 

[Steve C]

I would say your problem is most likely that you've used a relatively slow powder in an unsuitable application with a light weight bullet. AA#7 has a burn rate similar to Blue Dot and is more suited to high pressures of the 9mm and magnum cartridges. Accurate does not even list for AA#7 as a suitable powder in the .38 spl in their current data. An older free manual I have shows the only AA#7 use in the .38 spl as load of a 193gr Lead bullet with 5.9gr of AA#7 as a start load.

Go to ACCURATE POWDER to get current data for AA#7 in the 9mm and other cartridges its suitable for.

 

[greg531mi]

AA#7 is a slow burning powder, but great with FULL Power 9mm loads, it likes it hot, heard the powder was made for 9mm carbines......seems something is wrong with that can of powder, it depends on how you store it too....

 

[griz]

I think Steve got it right, #7 isn't suited for light 38 loads. You might be able to work up some stout high pressure 38 load with it, but why bother. Use it in the 9mm where it will work great.

 

[bakert]

AA7 is not a good choice for .38Sp. From what I read some years ago in an article by I believe by Dean Grennel, after a certain point, even a small amount can cause dangerous pressure spikes. AA7 does work very well in 9MM though. For the .38s, AA5 is one of my favorite powders. Reasonably clean burning and some good velocities.

 

[theHeretic]

Perhaps I was unclear. I am aware that AA#7 is better suited to higher-pressure cartridges. I was not trying to disparage this product.

Even so, given that the primer detonated was able to push the bullet into the barrel, it should have caused some of the powder to ignite. This did not happen. In fact, the powder was found packed in the barrel and had obviously been subjected to the primer flash.

My question is about the conditions that would cause powder, any of the modern powders, to fail. I was unable to detect any indications that would cause me to think that there might be a problem prior to the incident. Since I do not know under what conditions it was stored, I am looking for clues. It metered quite nicely [in fact better than Unique] and did not appear to have excessive moisture.

 

[redneck2]

Trying to explain this the best way I can...

"slower" powders (relative term) have coatings that retard the burn. It takes heat/pressure to overcome the coatings. If you don't have enough heat and pressure, they won't burn, or burn completely.

If you have a "slow" powder relative to the bore/case you can pop the bullet out with the primer. You never generate enough heat/pressure because the bullet has already moved and created too much volume.

Opposite happens when you use too much of a too fast powder, have too little volume, or too heavy of a bullet. Powder burns, creates heat which makes the powder burn faster, which creates more heat and pressure quicker than the bullet can move. Little pieces of the gun litter the landscape.

HTH

 

[Steve C]

I had a similar FTF with a load of 2400 that was contaminated by the case lube I'd used. This was many years ago when I was using steel dies and new to reloading. The unburned powder was yellow in color and had a oily look to it.

If the powder isn't obviously bad, ie sour odor, or show signs of contamination then its probably a problem with the load.

Ball powders are harder to lite off than flake powders. Such squibs are noted in powders like H110 or W296 if loaded too light. I still think the reason you got the squib was a combination of too low a powder density, too light a bullet and using a standard primer. Not enough fire and not enough pressure is allowed to build so the powder didn't burn.

If you would change to a 158gr bullet or 148gr bevel base wad cutter and magnum primer you probably won't have this kind of squib load.

Redneck 2 gave a good explanation.

 

[redneck2]

Sometimes there's a pretty fine line between what works and what doesn't

Anything to "heat up" your load slightly (within load limits) can help.

I'm not familiar with CCI's numbers. If 500's are standard, I'd try WW's as they're hotter than standard and on the low end of magnum. I've had good results with them with AA5 and most all other handloads.

Sometimes a hard crimp that stops the bullet jumping out from the primer is the cure.

Just raising the charge a few tenths (again, per recommendations) or making sure seating depth is correct may be enough

I had problems with my .45acp. Upping the charge slightly from minimum and reducing oal solved the problem.

 

[griz]

I don't believe anything about the load "failed". Powders designed for higher pressure just don't light well under those conditions. I ran into the same thing trying to use AA #9 in a light 357 load. The bullet always left the barrel, but there was lots of unburned powder in the barrel, all over the cylinder, and on the bench in front of the gun.

 

[CZ57]

I agree with you guys that this is a case where the powder was not the best choice. #7 for .38 Specials below +P, or #9 for light loads in .357 Magnum. These are high performance powders and there's really no good reason to use them in a lower velocity load. For high velocity/pressure loads they shine. One other factor in the burn rate of Accurate powders is that burn rate is effected by the level of nitroglycerin added because these are Double-Based powders. #5 is considerably higher in nitro and much easier to ignite. A much better choice for the .38 Special until you get to what would be +P+ level or +P with heavy bullets. Many guns are not designed for it, hence no recommendations from Accurate for its use.

 

[8ring]

I have experienced the same phenomenon that Redneck mentioned. I got a couple squibs using a relatively light load book load of Universal in .357mag, a light crimp, and a magnum primer. There was a load pop and considerable smoke from the cylinder. Unburned powder stuck to the base of the bullet in the bore.

I believe the magnum primer blew the bullet out of the case before the powder could completely ignite. That's my theory anyway.

Try your #7 in .357mag with medium weight bullets.

Chris

 

[Powderman]

I just took a look at the online AA manual, specifically the load data for .38 Special, found at: http://www.accuratepowder.com/data/...oadsHandgun/38 S_W Special pages 97 to 98.pdf

AA #7 is not even recommended for light weight bullets. The only data I see for AA7 is with heavy (almost 200 grain!!!) bullets.

Now, if you have a .357, it seems that AA #7 can be used for quite a few load combinations. Check it out at:

http://www.accuratepowder.com/data/...dloadsHandgun/357 Magnum pages 100 to 102.pdf

Good loading, and good shooting! Remember to use a good roll crimp, too.