Manual discrepancies....


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armoredman
December 18, 2005, 11:25 AM
I requested some new 9mm load data from Hornady for thier 115gr XTP, which they were kind enough to copy and mail to me, with thier newest catalog of very cool stuff...at the same time a friend gave me a copy of the 1991 Hornady Handbook of Cartridge Reloading - very cool.
BUT...stuff doesn't jive...
Listed under 9mm 115gr for instance, the 91 lists AA#5, which I use , the latest doesn't. The starting load for AA#2 in 91 was 4.7gr, max 5.9gr. Now the starting is listed as 4.3, top at 5.1! The COL changed from 1.050 to 1.075, too. Do manufacturers do this a lot? I have been using older manuals for some time, what's up with this? Are my reloads that were well within limits now dangerously overloaded? Sheesh!

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Uncle Don
December 18, 2005, 11:30 AM
It's not uncommon to find such discrepencies, especially when looking at older manuals compared to the newer ones. We live in a litigious society and the powder companies need to be "conservative with a cushion". I use one load in which I'm .7 grain over the the manual and according to the chronograph and pressure signs, it's still plenty mild. However, the load is listed in an old manual I have.

While I don't advocate going over, I'm simply saying that newer manuals are printed with liability in mind.

dakotasin
December 18, 2005, 11:31 AM
data is going to vary from manual to manual, and data is going to vary from year to year as powder lots change, bullets change, etc... data also varies widely from gun to gun.

as for your specific load... i don't do 9mm, so somebody who is more versed in 9mm will have to help you out. but, i do know that i use reloading manuals as a guide for where to start, and then i let the gun tell me where it wants to operate (and where its individual max is - no manual can tell me what the pressure is for my individual gun and chamber w/ my specific components and lot #'s).

RecoilRob
December 18, 2005, 12:22 PM
A lot of the powder companies changed their pressure measuring to electronic strain guages and this showed instantaneous peak pressures exceeding the max allowed, so they reduced the charge recommendations.

The older ways to measure pressure showed more of an 'average' pressure and were not as sensitive to rapid peaks so some of the older loads could be considered overloads now.

Of course, the Lawyers have had an influence on them too I'd wager. If ANYTHING shows overpressure.....even if 1 Billion rounds had been fired safely at the old levels....they would be forced to reduce it or face the possibility of being unable to defend themselves in court.

The Bushmaster
December 18, 2005, 12:29 PM
Don't you just love this "Sue Me/Sue You" society we live in these days...Everyone is trying to get rich off of someone else. Leaches...:cuss:

Ol` Joe
December 18, 2005, 12:48 PM
Rumor has it before AA was bought by Western they bought their powder from various over seas manufactures to "meet" their criteria. Keeps prices low, but not the best way to get real good lot to lot consistancy.

The manufactures also show the data for a bullet wgt in most cases, not for each bullet of that wgt listed. HP, RN or SWC for example. They give the max load for the bullet showing the highest pressure and velocity and the rest in that wgt may well take a couple more grains of powder to equal the published result. There are likely other causes for data changes in the books, legal, component, error, ect, but I doubt any manufacture will come out and state exactly which is the cause.
BTW, I`ve also heard of manufactures altering bullet geometery slightly (bearing surface, ogive ) without anouncing the changes. The new books show the change in data, likely very small, but until then they rely on their "work Up to max" warning to keep people safe.

armoredman
December 19, 2005, 10:35 AM
I can't see any signs of overpressure in my loads from the old manual, so I think I'll keep using them - I will say one starting load I did was so light I worry about detonation! I am pulling those bullets today, and starting over.
As for bullets used, I use Remington 115gr JHP and Hornady 115gr XTP right now.

taliv
December 19, 2005, 11:32 AM
in addition to the reasons above, keep in mind that the formula for a given line of powder may get tweaked over a 20 or 40 year period.

i'd recommend using a manual dated within a few years of the powder's date (for those of you who are still shooting powder from the stockpile you made 20 years ago)

except for military pulldown powder, i only use relatively new powder (my oldest is 3 yrs old). so it's not really a consideration.

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