powder charge question

[Hawken50]

I'm new to reloading (loaded and shot my 1st batch today) and have a question. if 2 manuals have 2 diffrent max and min. loads for the same powder and bullet, which should you go by? split the diffrence?

i ask because i'm shooting 60grn sierra jhp and imr4064. sierra's book lists min at 37.6 and max at (appx.) 40. on the other hand the imr website lists 40 as min and 43.8 as max. both are listed for the specfic bullet and powder but they don't even cover the same ground. a little help?

 

[taliv]

dropping that far down shouldn't be dangerous so i'd go with the lower starting value.

however, what are the dates on the book? and when did you buy the powder?

 

[ocabj]

I'd trust the powder manufacturer's numbers higher than anything else, but data can always be listed incorrectly. I'd go with lower numbers first (in this case, 38 grains or so) and work your way up. Once you chronograph the starting loads, you'll have a good idea on how far you can go.

 

[Hawken50]

thanks for the help.

taliv- i just bought the powder. the data is from imr's website, so i'm assuming it's current. i'll have to get back to you on the book date.

ocajb- little problem, i don't have or have access to a chronograph. anything else i can do?

 

[ocabj]

Hmmm... well, chronographs are good ways to check to see if you are shooting a load too hot or not hot enough. You might want to look into buying one in the future.

Just follow the basic rules in handloading manuals for checking for high pressure loads such as: checking for cratered primers, soot around the primer and case head, blown primers, and a stiff bolt to open after firing round. People also look for backed out primers. I honestly don't think this is a good indicator because I've had this happen with lots of loads that were very mild and this can be caused more by longer headspace or low pressure loads rather than high pressure loads.

 

[trickyasafox]

for a mild load i go a few tenths higher then the lowest listed, for a midrange with the spread you discribed i'd split the difference

 

[Headless Thompson Gunner]

The brand of primer and case you use can affect the pressure generated by a load. So can the bullet seating depth. So it's possible that by using different combinations of these other variables for them to come up with two different ranges of "safe" charge weights. Each range is correct, for it's own unique set of variables. See if there are any such differences in your two sets of data.

You don't always have to start at the absolute minimum. Starting somewhere in the middle is usually safe. Pick a midrange charge and carefully check for signs of high pressure. Then adjust up or down as needed. I doubt this practice would be dangerous, so long as you careful and cautious about how you proceed.

 

[Rico567]

I'm not that familiar with the sources of your info. My first suggestion is that if you have two references that disagree- go for a third opinion. Find an independent third source and see how it compares to the others.

My second observation is that older manuals and sources tend to have stronger maximum loads than more current references. Whether this means they have been "lawyerized" to protect against litigation, as some have suggested, I don't know. I do know that my old Speer #8 manual and the current #13 have significantly different maximum powder charges for many loads.