Confusion and Paranoia

[jaycee]

Any reloader knows that between lot #'s of powder , pressures and consequently velocity can and does vary.

[ET1]

Jaycee

Yes that statement is true but in this case with 4759 it does not apply. Powder manufacturers keep a reasonably close tolerance to the powder they manufacture. Not a difference of close to 10%.

The old 4759 came in 1/2lb cans and for years after many cans used the average velocity of 2300fps was experienced with 43grs. Then Hodgdon bought IMR and not long after that the 1lb plastic container of 4759 appeared. Here other shooters began to experience a loss of about 100fps with their 43gr load with the 1lb plastic container of 4759. In order to regain that velocity most found that by changing that load up 46.5-47grs they again acquired 2300fps. I also did a PT test to see the difference between the two 4759 powders and got a difference of about 5000 PSI.

Now if you want to believe your statement about lot variance applying here you go right ahead.


Ed

[MikePal]

Any reloader knows that between lot #'s of powder , pressures and consequently velocity can and does vary.

Powder manufacturers keep a reasonably close tolerance to the powder they manufacture. Not a difference of close to 10%.

I find it hard to believe that a powder manufacture like IMR would allow a variance in production between lots outside a fairly tight tolerance to the spec. I used to do Spec Functionality Audits with companies like IMR who supply to the government and they wouldn't be in business long if they couldn't meet the specs with every lot #.

[Big Jack]

Mike normally you would be correct. 4759 had some pretty major swings. 200 fps has widely been reported.

[MikePal]

Mike normally you would be correct. 4759 had some pretty major swings. 200 fps has widely been reported.

Makes me wonder how many of the issues that were reported were actually from a variance in the powder itself or simply the other variables affecting the load. A change in primer can see a 200 ft/sec change in velocity.

It would be interesting to find out the real reasons IMR stopped production, maybe more to the story than just "outdated technology, high manufacturing costs and low sales".

[Big Jack]

Not primer related. Even Chuck Hawk reported in on it.

With other powders I don't see that much of a swing maybe 30-50fps which is nothing much in my book with a cf.