First round of load development now what?

Discussion in 'Reloading' started by GSoD, Apr 20, 2008.

  1. GSoD

    GSoD Well-Known Member

    Messages:
    45
    Joined:
    Nov 22, 2007
    Hey,
    Well, I actually pulled it off. Finally took my first batch of reloads to the range. All fit in the magazine, all fed, all fired, none blew up in my face. Had a couple of fliers but I expected that as I was having some consistency troubles with my bullet runout (seating die problem I suspect)
    Couple of questions for the pros :

    a) Is my math correct?
    I measured my best group from outside edge to outside edge of the two furthest holes. They measured 1.35" apart. I was firing at 200 yards, so I figure I divide by 2 to get an approximate 100 yard reading. This gives me a reading of .678 inches. I then subtracted the caliber of the bullet to give me the centre to centre reading. .678 - .308 equals .370.

    Did I do this right?

    b) Now what?
    My best group (.370 if I measured correctly) mentioned above was acheived with 44.4 grains. At 44.7 grains the group increased to .518" and at 44.1 the group increased to .567" What is the next step? Do I put together batches in .1 grain increments from 44.2-44.6? Should I consider .370" to be pretty much as good as its going to get with an out of the box non-custom rifle, slap a bunch together at 44.4g, test for repeatability and chronograph for suitability for long range?

    c) Too much?
    Lets say I stay in the 44.4g neighbourhood. Is this an excessive load in regards to will it shorten gun life or invite early catastrophic failure or is this a happy place to be?

    d) No pressure signs?
    I worked up from 42g of Varget to 45g of Varget and inspected each case after firing. But I didn't notice any obvious pressure signs. No cracked necks, no flattened or pushed out primers. No visible signs of case seperation. Is this normal or is this confirmation I don't know what I'm looking for?

    SPECS:
    Gun - Remington 700P with Jewell trigger set to 2lbs
    Caliber - .308
    Barrel length - 26"
    Bullet - 175g Sierra HPBT
    Powder - Varget
    Primer - CCI
    Brass - Once fired federal, full length re-sized, trimmed once to 2.015
    OAL - 2.810
    Load development range - 200yards
    Load increments - 42g-45g in .3grains
    Best load - 44.4g with .370" group
    Goals - 99% Recreational target shooting from 300-1000 yards and !5 Moose hunting within 300 yards.

    PS - Thanks to everyone here who has helped me directly by answering my questions or indirectly by posting their info. I can only assume this is why my first time out was such a riot success.
     
  2. rocky_lange

    rocky_lange Well-Known Member

    Messages:
    182
    Joined:
    Jan 3, 2008
    44.4 of Varget should have no ill effects on your rifle. My sweet spot is 44.5.

    Yes, you can dial it in by .1 gr increments and chrono them. If you get similar groups sizes with a few different loads, I would stick with the load that produced the smallest standard deviation.

    Want to go further? Next step, start adjusting catridge overal length. Start with jamming the bullet into the grooves a few thousanths if your magazine well will allow and the back off to a SAAMI length. You might find a tighter group there as well.

    Still want more? Play around with the crimp. Some bullets like a little more neck tension than others before making the jump to the throat. But, most important, you can use your bulllet seating die to apply a light crimp. I did say light crimp, right? I have gotten a little zealous with crimping with my seating die and crushed a few cases. Best to use a crimp die like Lee offers, they are more consistant.

    Oh yeah, don't forget to check trim length on the brass as well. Keep them even. If crimping with a seating die, longer cases will crimp more than a slightly shorter case.

    These are the steps I follow and have had good results. Can't say everybody will agree that they are neccesary and some may say not to work up loads this way at all. Like I said, this is what works for me.

    Rocky
     

  3. mattj

    mattj Well-Known Member

    Messages:
    213
    Joined:
    Jun 27, 2007
    Your group size math is a little off. You want to subtract bullet diameter from the original group size before you do the division.

    1.350" - .308" = 1.042" center-to-center at 200 yards.

    1.042" / 2 = .521" (IPHY)... still not bad :)


    Your result would be correct... if you were shooting .616 caliber bullets ;)