Originally Posted by Nobody
Been a member for sometime though I rarely post. Do a lot of reading though.
I have a 264 Win Mag Sendero II. It's got a 1/9 twist, standard Remmy trigger though it's all been worked over by Clarence Hammonds. I'm trying to develop a load for it using 140 SMKs. I'd called Sierra and gotten a load range of something like 55.?grs - 62?grs of IMR7828. I can fire a couple of rounds and have them touching and the next three rounds are 3/4 of an inch out. Typically, I start at mid-range - I feel that's a safe thing to do though with 264s you gotta' be careful because they generate pressure spikes with even slight changes to load weight.
Anyway, I've got through like...25 rounds and I'm still no where near where I think this gun should be. My question, as the title suggests is, how many rounds should I reasonably expect to have to shoot while developing a load?
And by the way, if anybody has a good, safe load using IMR7828 or IMR4831 please let me know.
Thanks in advance.
I use a chronograph for the process of eleminating bad loads and don't worry about group
size in the begining.
It goes something like this=
First I select the bullet I would prefer to use.
Then I look at loading data for powder that has maximum performance and velocityat 100%
Next I load 3 rounds ,each with different powder charges starting midrange and moving
up to Max listed load by .5 gr increments.
Repeat the process with the next best powder listed.
Now its off to the range to test the loads. Make a log and keep very good records on all the
test loads (Even the bad ones) they will come in handy later on.
Start with the lowest loads and work up using the crony.
I eleminate based on bad SDs sometimes with only 2 shots and save the other rounds for
fowling shots or pull the bullets and reload to save the brass from to many firings.
Once you find good Standard deviations then zero in on powder charge,seating depth,primer,
even bullet type (Same weight).
With out good SDs you will never have good groups at long distances because this is the load
burn consistancy and with velocity changes vertical and horizontal stringing will drive you crazy
even if everthing else is good .( Like bedding ,barrel twist ,trigger pull ,ETC.
This process has saved me many rounds of testing and lots of brass over the way I use to do
my load development.
So now I some times luck out and find a realy good load after only25 or 30 rounds down the
tube but sometimes tweeking to get the very best load can add another 20 or so rounds to
Be patient and it will come.
Just the way I do load testing
J E CUSTOM