No. 7 "out" For .38sa?

[Peter K]

Hi,

some years ago Accurate No. 7 was very popular for .38SA or 9x21. Nowadays a lot of the guys and grrls use VV or IMR or Hodgdon. Why is this so? Is No. 7 no good anymore?

[Larry White]

AA#7 does seem to have lost some appeal, but its as good as it ever was. Some of the newer powders are cleaner and may have fit the new power factor a little better and I dont know anyone who has done any work with #7 and major 9. I still have some and if I was going to go back to open I would use it.-----Larry

[George]

Love AA7 for major 38 stupor, but unless you can load long like stupor it's a total loser in 9x19 & 9x21 at short OAL's. Just cannot get enough in the case to make major under anything but a heavy bullet.

--

Regards,

[Harmon]

that stuff is just plain nasty!

after you finish shooting a match it looks like you dipped the slide in black sand..

IMR4756 is better by far.

Power Pistol is excellent choice too

[BSeevers]

AA7 will erode your barrel quickly. Yes I have seen it. That was at 175PF and might be reduced at the new factor but there are so many other good choices. It is a bulky slow great comp powder that produces a lot of gas for the comp. My last barrel with it lasted around 25K.

I think "sand" is what erodes the throat. It would be interesting to see how hard that residue is.

[Harmon]

im thinking the same may be true with true blue or troo bleau or true blew how ever you want to call it.

HS7 is also pretty bad.

VV powder of any flavor would be better than AA7, HS7 or True Blue..

If you can get some IMR4756, try it...i really liked it.

[George]

Won't buy the AA7 bad rap. Almost did, stuck with it and now never, ever will. It's just a theory and not a fact and just because AA7 doesn't burn as clean as you might want it to in a certain setting, that doesn't mean it won't work fine in a setting optimized for it's burn rate (sloooowww).

I don't/won't buy the "it erodes barrel" routine as being a fault of the powder. Only improper application of a powder will do that. Too much barrel lead allowing too much flame front past before full obduration, or too slow of ignition flame front spread and initial pressure peak rise also slowing bullet obduration and sealing. This is what is most likely at fault, not the powder itself. Take a look at barrel leade in the barrels that folks think AA7 wore out, it was probably generous to start and allowed for a lot of throat torching.

Barrel wear is all about the throat and if the bullet seals right away, the wear rate will be the same as any other powder that drives the obduration process at the same rate and generates the same end pressure result. The pressure generated regulates the heat and therefore the erosion rate. If the peak pressure of a powder is similar and the peak rises at the same rate, then the temp rise rate is similar and the erosion rate is similar, just plain physical fact.

Seal the bore at the right time and barrel wear will be normal. Seal it late and wear will happen faster. 50,000 psi is the same temperature in the same size enclosed space no matter what powder generates that pressure. The pressure/temperature and the time the metal is exposed to it is what erodes the barrel metal, not the type of powder that generates the pressure. If the pressure curve is the same, the temperature curve will be same and the erosion rate will be the same (I've said this earlier, but it deserves repeating).

There has to be another reason for this extra erosion folks seem to have found (if it is there), so "if it is there" it has to be due to a factor unrelated to temp and pressure. Slow bore sealing is the most likely culprit. Fix that, you fix any erosion issues (if they existed).

Something to keep in mind: If a powder generates a faster flame front and initial peak, it will kick a bullet in the pants early and seal the bore right away. Now if that powder also burns a little faster overall yet, is formulated so as not to create overpressure situations, then this powder is going to exhibit better berral wear in a barrel with a generous leade. A slower powder that obdurates the bullet slower/later and therefore lets a bit of flame lick the barrel ahead of the bullet a tad will wear the barrel faster in that same barrel leade. This is not a problem with the powder, but rather a problem with the choice of barrel leade and/or bullet hardness/softness. Fix the real problem instead of taking aspirin.

--

Regards,

Edited August 14, 2005 by George

[BSeevers]

I disagree its only a "theory". Call Wil Schumann of Schumann barrels or George Smith of EGW or a Lot of other people. I really don't care what anybody uses but if you don't want a early eroded barrel my experience is stay away from AA7. Trying to help other shooters. NoBody makes this statement about VV, IMR, Hog, or most any other powders. YMMV but as I said 25K for me. My last barrel on 3n37 was 60K+ and I replaced it more on principle than on barrel throat wear or accuracy loss. Although it was wild to hold up the old "smooth" bore compared to a fresh Schumann.

[shred]

My take (I've used a lot of slooow powders in my 9x25 days..):

Dirty = unburned stuff. Unburned stuff = particles. Particles @ 50K PSI/1400 fps = sandblaster.

[George]

Can't buy the grit issue as having anything big to do with the erosion in comparison to the cutting torch effect that happens when hot gas runs ahead of a projectile for a little bit of the bullet travel.

The small amount of grit being ground in by the projectile may be actually lubricating the situation at this pressure point ;-)

[Harmon]

Its nasty and there are better powders such as but not limited to:

N350,

3n37

3n38

IMR4756

IMR7625

Power Pistol

and SP2..

SP2 shoots good, so does 4756, 7625 and power pistol..

ask some GMs and Masters what they load...benny hill is probably one of the few that use AA7.

ive been playing with the IMR powders, probably gonna stick with 4756 despite the fact that it can be a pain to load!

[mike4045]

Not sure about the erosion problem, but it is very dirty. Ran AA#7 side by side with 7625 and it was alot dirtier. 7625 also shot smoother and flatter. With #7 about 200 to 250 rds of practice and I had to clean the gun. With 7625 I got thru an entire practice session about 500 rds before cleaning. It was no where near as dirty as #7.

Mike

[TWHaz]

My take (I've used a lot of slooow powders in my 9x25 days..):

Dirty = unburned stuff. Unburned stuff = particles. Particles @ 50K PSI/1400 fps = sandblaster.

I have to agree.

I tried some longshot in my 38 super.

Shooting 7.3g it was some what clean.

Shooting 8.0g it left flakes and grit, that turned my blaster into a single shot after 100 rounds or so.

4756 or 3n38 are sure cleaner.

[G-ManBart]

I disagree its only a "theory". Call Wil Schumann of Schumann barrels or George Smith of EGW or a Lot of other people. I really don't care what anybody uses but if you don't want a early eroded barrel my experience is stay away from AA7. Trying to help other shooters. NoBody makes this statement about VV, IMR, Hog, or most any other powders. YMMV but as I said 25K for me. My last barrel on 3n37 was 60K+ and I replaced it more on principle than on barrel throat wear or accuracy loss. Although it was wild to hold up the old "smooth" bore compared to a fresh Schumann.

If you've seen it, what were the specifics of the barrel errosion? What kind of barrel, what were the conditions, i.e. how hot did the person get the gun before taking breaks etc?

I put 65K+ rounds of the old power factor with AA #7 through my old open gun (Bar-Sto barrel) and the accuracy was just as good at the end as when it was new. I sort of lost count there after 65K so it could be more like 75 or 80, but I can't be sure. If the powder was a problem I think it would have shown up in that amount of use. If it takes 100K plus to make a difference, what's the big deal? Most people are going to replace the gun by then.

There was a run of #7 a long time ago that had a problem. That's when the "theory" got started even though the problem was eliminated quickly.

[George]

There was a run of #7 a long time ago that had a problem. That's when the "theory" got started even though the problem was eliminated quickly

That is the same source for this vicious AA7 rumour I had heard. If the grit isn't as hard, or harder than the bbl steel itself, it ain't gonna' wear the bbl. I still say it's torch cutting at work in the first part of bullet travel and has nothing to do with the powder itself. VV under an undersized FMJ will eat a bbl out real fast too

[shred]

There was a run of #7 a long time ago that had a problem. That's when the "theory" got started even though the problem was eliminated quickly

That is the same source for this vicious AA7 rumour I had heard. If the grit isn't as hard, or harder than the bbl steel itself, it ain't gonna' wear the bbl. I still say it's torch cutting at work in the first part of bullet travel and has nothing to do with the powder itself. VV under an undersized FMJ will eat a bbl out real fast too

So, water can't cut through rock then? smashing soft stuff into hard stuff at high velocity eventually wears things out. It's real obvious in the comps of 9x25's-- shoot a not-all-burning powder and the comp erodes significantly faster, with a speckled pattern, than powder where everything gets burnt, all else remaining the same; bullet, cases, powder charge, etc.

[GentlemanJim]

WE ran many tens of thousands of rounds in 9 mm major with no visible wear or erosion.

AA7 works very well with heavy bullets..not real clean but not bad.

we were using 168gr hard cast lead @180 PF loaded to 38 super OAL

When we started shooting again..we tried AA7 with 124gr JHPs.. it was MUCHO DIRTY.

AA7 served us well with the old loading...now we use HS6...quite clean..and does a fine job.

Jim

[George]

Comp erosion from unburnerd powder is still due primarily to torch cutting from the flame/pressure front still being at cutting torch temps. The supposed sandblasting effect of unburned carbonized cellulose is not significant, or of any effect at all in comparison to a randomly dispersed flame front of burning gas at 3k degrees and moving at 3000fps+ (the gas is way faster than the projectile). The sputtering flame pattern of unburned particles mixed with flame tongues is almost certainly what creates the specked pattern, not impact from carbonized cellulose powder particles.

The time particulate spray erosion takes compared to heat erosion is evident by comparing the Grand Canyons creation time to how long a plasma torch takes to cut stainless steel

BTW, tool steel is at least an order of magnitude harder than any rock material of igneous sedimentary type.

[Bob Hostetter]

Most of the problems with AA powders came from when they were first released to the USA market (early 90's?). They did cause barrel erosion much quicker then a lot of other powders and they did it with all brands of barrels. I saw a lot of barrels with lead area and rifling erosion and it tended to look like the bore was sand blasted. If I remember correctly we discovered that AA was using a glassine (?) compound to help control the burn rate of the powder and that was the cause of the problems. They changed the compounded fairly quickly and the problem pretty much disappeared but the stigma has stayed with the AA powders with a lot of shooters.

Also keep in mind that this was the time when we had started using lots of slow burning powders in high pressure 9mm bore cartridges. A lot of people were using bullet weights as low as 100gr's to make major with in the 38 Super. Slower burn rates, higher pressures, higher velocity's, and higher heat all cause faster barrel wear.

By the way using water as an example of something soft cutting something hard is not a good example. Since water doesn't compress very well it should be considered very hard, especially at high pressures or velocity's.........

[George]

and YES, it WAS one single batch of powder that did this. This happened way early in the product life and that one incident has cemented this tale in place ever since. And by "George", this present untruth absolutely needs to get laid to rest as the "no longer true" thing it really is. I have used AA7 since 1989 and still use it today. The bad batch thing was way, way back and has NOT happened since.

Regards,

[bwit]

A friend and I just tried some .38 Super loads today for open w/ AA #7. They were excellent, clean and loud because the gas supply is huge and the flattest shooting open guns I've seen. The C-More dot jumped slightly and returned to where it started. I made you want to keep pulling the trigger, and keep pulling and keep pulling . . .

[PJ BAD]

As BWIT said, we loaded up a bunch of AA #7 to test on Monday and couldn't believe our eyes! We used Benny Hills formula of 12.2 grains over a 115 grain HP at an OAL of 1.260. The power factor is around 180 but it worked the comp better than anything we had ever shot. Its extremely loud and even more so because we were shooting under a canopy. As far as being dirty, I don't think it was any dirtier than the 7625 I've been using.

As always, Your mileage may vary!

[slidelock1]

I disagree its only a "theory". Call Wil Schumann of Schumann barrels or George Smith of EGW or a Lot of other people. I really don't care what anybody uses but if you don't want a early eroded barrel my experience is stay away from AA7. Trying to help other shooters. NoBody makes this statement about VV, IMR, Hog, or most any other powders. YMMV but as I said 25K for me. My last barrel on 3n37 was 60K+ and I replaced it more on principle than on barrel throat wear or accuracy loss. Although it was wild to hold up the old "smooth" bore compared to a fresh Schumann.

I HAVE talked to Wil Shumann (April 19, 2007) about AA7, and he stated that at one time AA7 was in fact a gritty powder that eroded the barrel. However, it was completely reformulated years ago and that now is is no more erosive than any other powder out there. He mentioned the fact that he has used several HUNDRED pounds of it through his open gun with no erosion! He also mentioned that Hodgdon had a similar problem with HS7 eroding barrels and Hodgdon reformulated HS7 and renamed it Longshot. Maybe Accurate should have renamed AA7 to put to rest the bad rumors about it, but be that as it may, I have used several kegs of it in my open gun with zero erosion observed! So, if you like it, use it without fear.