Going to Magnum Primers what should I do????

BHLBAMA

BHLBAMA

New member
I am having to go to Winchester Mag primers for my 300 Weatherby Mag. The large rifle primers were giving me a delayed firing. My question is how much less Powder should I start with or can I use the same load??? Its only a gr above starting loads and 3 grs below max. All my manuals have large primer recipes and this will be the 1st time I have used the magnums.
 
thanks fellows I looked at Remington factory ballistics sheet and the 300 Win Mag using the regular large primers had 2650 velocity and 2339 energy using the the Mag primers it showed 3290 velocity and 3605 energy using the same 150 gr bullet. Does it really make that big of a difference???? This is the reason I asked to be sure on starting loads. thanks
 
There is more different between those loads than just the primer. Changing primers normally makes very little difference, or none.

Jack
 
If you have worked up a maximum load, using standard primers, when you switch to magnum (or any other) primers, I would back off a grain or two and work back up. Chronograph data generally indicates about 1 grain difference in powder to achieve the same velocity. The pressure curve is also being altered: magnum primers have a hotter flame, of longer duration. The powder is being ignited at a different rate. I am always cautious of any substitutions.

If you are having delayed ignition, I would look hard at the sizing of your brass. You could have a "short" belt on the brass, and a "long" belt in your chamber; both are made within "tolerances". It could easily be a bit of slop, allowing the cartridge to slide forward under impact of the firing pin, resulting in erratic ignition. Try neck sizing some fired cases, and see if the problem goes away. If it does, then adjustment of your sizing die should take care of the problem, as well as extending your brass life.
 
Quote:
There is more different between those loads than just the primer. Changing primers normally makes very little difference, or none.

Jack



I thought the same thing Jack it may be a misprint but I wondered and thought I needed to ask after reading this. thanks
 
THanks for the tip Onion...... Ill be making that move next if the Mag primers I loaded up tonight with the same powder dont fire right tommorrow.
 


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