10mm with AA#7 From Hornady manual

[sargents1]

I have a bit of a dilemma. I pulled some load data from an old 7th edition Hornady manual that lists

155gr Hornady XTP HP
15.1 Gr AA#7 (Max Load)

So, being the cautious fellow I am, I knocked half a grain off that and loaded up a dozen or so cartridges. Now I have a handful of shiny new 10mm loads with 14.6gr of AA#7 in them.

Then, I checked a few other sources and found Nothing over 13.5gr for a 155gr bullet and AA#7. Going by what these other sources say, I now have a dozen little hand grenades....these are at least a whole grain, maybe 1.5gr over Max.

Has anyone tried that 10mm/AA#7 data from the 7th Edition Hornady manual?

I am running a Glock 20 with a Lone Wolf barrel and 22# recoil spring and I really dont want to blow up my gun...nevermind my hands, face etc.

 

[rcmodel]

Nope.
And I wouldn't either. Not yet anyway.

As for the "old" Hornady #7 manual?
It can't be too old, because my #6 came out in 2006.

It shows 11.9 START - 15.1 MAX too.

It would seem if it was a misprint and folks were blowing themselves up, they would have corrected it before publishing the #7 manual.

So, being the cautious fellow I am, I knocked half a grain off that

Being cautious would be using the recommended starting load and working up.
Or at least reducing any published MAX load by 10%.
That would give you 13.6 grains to start.

Were I you, I would set your grenades aside for now.

Then load some more at a safe recommended starting load and work up.
If you get back up to the 14.6 loads, without bulging brass or other pressure signs, you are good to go with them.

rc

 

[sargents1]

Yeah, that's what I figured.

I was hoping someone would reply "Sure, I have a Glock 20 and I have loaded right up to 15.1gr and its A-OK.", but I guess that is probably a stretch.

Thanks.

 

[rg1]

Hornady 8th edition:
10MM Auto
Colt Delta Elite
case Hornady
primer Winchester LP
155 Hornady XTP oal 1.260"
A #7 start 11.9-1150 fps----12.4-1200----max 12.7-1250fps
Checked Hornady 7th edition and using the same components above they do list a maximum of 15.1 for 1450 fps with a start load at 11.9.
From Accurate Arms #1 Manual with Hornady 155 JHP at 1.250" oal they list 11.4 grains as a start and 12.7 as a maximum at 1379fps. They used CCI 300 primers in Hornady cases.

 

[Mike 27]

They greatly reduced the loads in the 8th edition. I ruined about 80 peices of brass with this load. I strongly recommend against using the data from the 7th and the AA7. I emailed Hornady on this one and their answer was that they tested the loads and had safe pressure with the 7th and when they retested in the 8th they lowered it. I think the 8th edition had a max around 13, but I still have not bought it. It was along the same lines as the Sierra and the accurate max loads. I had cracked brass and they were so over sized I could hardly get them to re-size. The primers were slightly flattened. I fired out of my glock 20 and if you really want to see a glock bulge this load will do it.

If you have tried the 14.6 with your pistol then you might be ok. I wanted to warn you that Hornady did back down the max though in the 8th.

Mike

 

[noylj]

First, the rule is to start with the lowest starting load you can find. The rule for starting loads is, if the manual doesn't show a starting load, to take 10% off the max load.
If the max load is 15.1gn, the highest starting load you should have started with would be 13.6gn.
My Hornady 8th edition shows start at 11.8gn and max at 12.7gn--so even the 10% below max load would still exceed the current data.
It appears from the Hornady manual that they were not getting good results with AA7, as AA5 shows a higher velocity. This tends to indicate pressure spikes/variations that limit them to "instantaneous" pressure where the instantaneous pressure at higher charge weights exceeded SAAMI maximum.
Thus, AA7 appears just from looking at one manual to not be a good choice for 10mm Auto. This has been a BIG factor in the changes in max loads as they no longer go by the max average pressure (such as the old CUP tests) and now know what the max instantaneous pressure is.
Your load is "probably" OK, as your gun can probably handle the short peak pressure (as reloaders have for decades before better testing came along)--though it might get "beat up" a bit, but I wouldn't risk it.
Always use at least two independent sources and always start with the lowest starting load.
You may want to look at Silhouette, Power Pistol, or HS6 as powders that meter well and perform well with such a light bullet.
AA7 appears to be an excellent choice for 180gn and heavier bullets--though AA9 would be an even better choice.

 

[GooseGestapo]

There have been several different manufacturers of AA#7.
Chek, Israeli, now St.Marks...
Secondly, the "early" data was worked up in Delta Elite's and S&W 1006 that have fully supported feed ramps in the barrels.
Later data is "Glock" compatible...

I had an excellent load worked up for the 200gr Hornady XTP and AA#7 back in the early '90's. It used the "then" published max load for AA#7.
I shot 3 of my loads through a Glock M20. The first two were later found to have the case buldges. The third round blew out the case head and damaged the slide stop.

Glock replaced the slide stop. I sold the gun promptly.

The next editions of all the manuals showed a 15% drop in powder charges for the 10mm to where it is only ~100fps faster than the .40s&w...

Do "drop" your charges about 15% with AA#7 to "work up" your charges.

 

[sargents1]

To all.

Thanks for the replies. I'm glad I didnt load a big batch because those loads are going in the trash (dont have a bullet puller yet).

The moral of the story is:

"Check Two sources BEFORE you load."

 

[Mike 27]

I would not throw them out. You will end up with a puller eventually. This is the exact load I ended up picking up a collet puller for and took down a number of rounds after trying to size the cases. It was an awesome load and I didn't realize there was a problem until I started sizing the brass.

 

[Shmackey]

When you load for 10mm, you're really loading for your specific gun--a lot like loading for bolt-action rifle. I'd have no problem putting those rounds through my ramped 1911, which seems to eat anything.

Most Glocks and some Deltas just don't have the case support for "Norma-plus" loads. Some Deltas, S&W semi-autos, Glocks with aftermarket barrels, and most ramped 1911s can handle them to a point. Then there's the S&W 610 revolver.

 

[hentown]

You'd be absolutely safe shooting those loads through the LW barrel! However, I'd start a little lower for the next batch.

 

[sargents1]

You'd be absolutely safe shooting those loads through the LW barrel! However, I'd start a little lower for the next batch.

That is a bold claim. Especially since the Chamber support on the LW is essentially the same as the OEM Glock. Neither one is what I would call "complete" support. Good, but not complete.