10mm 200XTP 13.0 AA#9 test

[preventec47]

AA9 powder.    The powder is too slow, and not dense enough to get the pressure up (unless you are trying the "lite" versions, which are misleading)..

What would be cool for a new Accurate powder would be a No.8, where charge weights would be similar to No.7 but with the potency of No.9.

Something like that could hypothetically give Longshot and 800X a run for their money.

/////////////
I already load and shoot with AA #8.  It is my standard go to with 155gr XTP bullets.
my AA #8 powder is a 50-50 mixture of #9 and #7.   What I have done is slowed
down the #7 and sped up  the #9.   I got my incentive from the pressure data from
Accurate Arms 3.2.2 10mm load data.   Look at the pressures for the 155xtp bullets
with AA#7 and AA#9 in the load data    see attached.  I load with Starline brass
and 16gr of my special mix AA#8  to exceed any of their velocity numbers and
I am pretty confident I am not exceeding the 37.5K pressure max  I 1st described this
about 2 years ago on another forum and was criticized for breaking the sacred rule
of not mixing powders.  I actually feel that I was just adjusting burn rates as the
powders are nearly identical in most respects.  Anyway, just wanted to report about
2 years of success with this approach and about 450 rounds fired.  I did approach this
incrementally however and built up to my loads.  I began with 10 percent increment
increases with #7 added to 16gr of #9 till I reached 50/50 and everything stayed cool.
BTW, I am shooting with SW 1006 but I dont feel like these are nuclear loads.
Just well balanced loads with a perfectly tuned power for the bullet weight,
case capacity and barrel length.



[attachment deleted by admin]

[The_Shadow]

Preventec47, do you have any velocity numbers from your testing? 
I did remember when you were discussing the mixing both the #7 & #9 powders but don't remember if you have velocity numbers.

[preventec47]

Wherever I was posting the info I am pretty sure I posted the velocity info as I purchased
a new chrony for the specific task and it worked great till I killed it.  Chrony devices
do not work nearly as well as gel for penetration testing.

[The_Shadow]

Sorry about your Chrony...I was just inquiring about some numbers based on the blended powders as tested...
Could you provide or share the load data and velocities as tested, so others can get a feel for your work?
I'm quite sure others will find the data useful as well.

[preventec47]

No I am sorry,  I did not keep up with the data.  But it exists in the forum where
you saw me present it which I dont exactly remember where....  Was it Glock Talk or AR-15.com etc ?

I am a bit rusty now but I did major investigation and study of internal ballistics and all I can
say is if ever anyone reaches a maximum load and there is still space in the case for
extra powder, then the powder for that load is not optimized.  More mass of powder equals
more gas that can potentially be developed to push the bullet out of the barrel for a longer
duration.    Such was my thinking with the AA data for the 155XTP.   At 12.7gr of powder, the
max pressure had been obtained with the AA#7 and there was still room in the case. Thusly,
the powder is too fast for that load.

Remember that the weight or mass of gas developed can never be heavier than the
powder from which it is generated.   So if pressures are limited to say a SAAMI max,
the powder producing the greatest mass of gas will push longer down the barrel and
create a greater average pressure for the time the bullet stays in the barrel.

With respect to the the Accurate Arms load data.......for 10mm 155gr XTP  ,
At 15.9gr of AA#9  clearly no more powder could be fit into the case yet the max pressure
was only 32,500. Thusly, the powder is too slow.   By combining both powders,  a compromise is made between AA#7 and AA#9 whereby the case gets
filled with the perfect speed powder that exactly fills the case and precisely meets the
SAAMI max pressure specification.   There may be loads of faster powders that generate
faster velocities, but I would bet good money that they are generating  higher pressures.
Laws of physics dictate it.    I could put it another way, for any two identical loads where
the powder weights are the same and bullets are identical and same COL and crimp etc.
the higher velocity load is generating the greater pressure.   Conversely if you had two
loads with the same pressure but one was a higher velocity, then that load had to generate
a greater mass of gas... hence greater volume and pushed longer down the barrel.
The powder that was converted to gas in the higher velocity load HAD to weigh more than the other.

[nickE10mm]

So, we STILL don't have any data for what kind of speeds a 200gr XTP w 13.0gr AA9 does in a 6" tube with CCI300's?

Darn....

Lemme know if someone maps this ....

[ShadeTreeVTX]

I'm interested in this load for my M-T and my 6.6" barrel in my G20sf - I don't have a chrony - no where I can use it :'(  ( yet)

Doug

[The_Shadow]

I do remember loading the 200Grain XTP's using the micro sphere AA#9 and it is a compressed loading and the nose of the bullet will start to show closure on the HP with some seater plugs.  In some instances the bullet can be pushed back out!  This was noticed even at 12.6 grains...

Use the least amount of case expansion as possible, to maintain best tension and avoid the bullet pushing back outward!

[475/480]

200gr XTP and 13.0gr of  AA9 ( Surplus WC820) in my STI 10MM -6" barrel got 1164 fps and yes a compressed load.


Sean

[nickE10mm]

Yea but I remember you got higher numbers from AA7 Than AA9 and I thought it was weird when you first posted that data, too.

I think your results are the exception rather than the norm...

For example, Taterhead got a 200gr XTP to 1200fps avg from a stock G20 barrel with 13.0gr. I suspect a 6" would get 30-60fps more, at least.

Anyone else have the data?

200gr XTP and 13.0gr of  AA9 ( Surplus WC820) in my STI 10MM -6" barrel got 1164 fps and yes a compressed load.


Sean