primers, powder, outside temperature 300WM

Discussion in 'Reloading' started by mt Al, Aug 8, 2009.

  1. mt Al

    mt Al Member

    Aug 4, 2009
    First post for me, been a lurker for a while. I've been reloading for a few calibers for a few years and didn't know how much I didn't know until I started reading these posts.

    Here are a few questions:

    I shoot 75gr RL22 with a CCI 200 large rifle primer and 180gr regular corelokt bullet in 300WM. I get pretty good accuracy with this load, plenty good enough for hunting out to 400 yds. I just bought some Nosler ballistic tips to try as well.

    I'd like to come up with an "all weather/all temperature" load for my 300. I have this for my .270 and have taken an antelope at about 550 yds and plenty of deer at 250 - 300 in the last 20 or so years in temps far below 0 and use non-magnum primers with H414. I might already have a good all temperature load for my 300 but have only sighted in and had hunting opportunities when its well above freezing.

    First question:
    First range tests with this rifle a few years ago showed better accuracy with non-mag primers.
    Is this normal (non-mag primers being more consistent)?

    Second question:
    Will the above load w/non-magnum primers work when things are very chilly? I live in Montana and hunt when its nasty cold outside. Do mag primers work better (for real) when its cold?

    Third question:
    I understand that Hodgdon H4350 or H4831 may be more temperature stable than other powders. Do these powders need to be lit with a magnum primer and can anyone comment on their real temperature stability?

    Fourth question:
    I've been building up brass from Remington factory loads and have about 3 - 4 reloads per case. Just bought my first bag of factory new brass (Winchester) and ran them through the sizer die. Is factory new brass less accurate than once-fired? Reason I ask is they they slid up and down the die with almost no force other than when the neck expander was on the way in and out of the neck and wonder if, upon first firing, accuracy suffers as the case expands to fill the chamber.

    Thanks very much for any insight, much appreciated.
  2. AJ Peacock

    AJ Peacock Well-Known Member

    Oct 7, 2005
    Welcome to the forum,

    I'll answer a couple of you questions.

    I use non-magnum primers in my 7mm Rem Mag and have never had problems in cold weather using H4831 and RL-22.

    I've shot terrific groups with new brass. I once had a load that shot lights out in new brass and just average in once fired. I had to adjust the seating depth and increase the powder a touch to regain the accuracy in fired/resized brass.


  3. britz

    britz Well-Known Member

    Mar 11, 2007
    Hello and welcome as well.

    As far as the factory brass question goes... no. the things you will gain from a once fired round (as long as it was fired in your rifle) is that it is now fireformed to your chamber. If you choose to neck size that is an advantage. Sometimes I have noticed slightly more runout in new brass prior to it being fired the first time in my 22-250. The reason it goes in your die so easily is that it is set down to factory SAAMI specs already where as your once fired ammo is bulged out to your chamber dimensions.

    You may wish to have your die set up so you are doing the minimum amount of resizing possible to help you gain some brass life. No need to push it back to to SAAMI specs if you are firing it in one particular rifle. You can find lots of information on this process often refered to as Partial full length resizing.