alice
New Member
I'm wondering if I should fill length size the brass for my new 300 win mag or neck size what do you guys think?
300 win mag question
- Thread starter alice
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ShtrRdy
Well-Known Member
I like to full length size to avoid chambering problems. You could try neck sizing only and see how it goes.
shortgrass
Well-Known Member
Is the brass once fired, fired in another rifle, or new? Factory rifle or a custom chambered blank?
Aoudad 101
Well-Known Member
I'm wonder same thing... I am using peterson long brass and 1 time fired ??
Neck size only for new brass. Partial length resizing after that.
And read up on only bumping the shoulder back vs. truely full length sizing a belted magnum.
I use these to help set up proper shoulder bump.
Competition Shellholder Sets - Redding Reloading Equipment: reloading equipment for rifles, handguns, pistols, revolvers and SAECO bullet casting equipment
Reloading equipment for rifles, handguns, pistols, revolvers, custom dies, bullet casting equipment, powder measuring and weighing equipment, bullet seating dies
Watch this video (maybe a few times):
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Wolf76
Well-Known Member
Usually neck size for 3 loads. Then I bump neck size with a forster die. Shoulder needs to move forward to chamber dimensions before bumping it back a 2 thousandths.
Left Hand Dave
Well-Known Member
Do whichever is more accurate in your rifle. Try both and go with what shoots the most accurate.
Wolf76 pretty well summed it up. Use a gauge to check the shoulder before pushing it back 2 thousandths. If you still have questions call me.
Here's a good read for reloading belted magnums. I use a Redding body die with the Redding shell holders and a Lee Collet afterwards but their are several methods that work well. Because the belted cases headspace off the belt, he "bulge" above the belt is often the tightness felt when chambering and is often mistaken for a shoulder that has grown (speaking from experience). A good, cheap piece of equipment is a cartridge gauge in conjuction with a headspace gauge, measure a factory case and once fired case and you'll have a great idea of how much to bump shoulders and when the body needs resizing. https://www.larrywillis.com/300winmag.html
Bob Wright
Well-Known Member
Look up Eric Cortina on Youtube to neck size or not. He's covered this question 8 ways to Sunday.
I use to neck size only when it was introduced years ago. Not anymore.
I use to neck size only when it was introduced years ago. Not anymore.
Always full length with .002 shoulder bump. Your brass will last longer and your bolt will always close even if some dirt gets in.
X2!
Retired CPO
Well-Known Member
If I shoot and reload and shoot again in the same rifle, I neck resize only. If I reload for someone else I full length resize.
Hi Alice. Neck resizing only works for some bolt action rifles and then limits the ammunition to being used in only that rifle. While not an issue when hunting alone if hunting in a group you would not have the option of sharing ammo with someone who runs out. Another problem with neck sizing only seems to be an issue with the necks cracking after only a few reloads. I never noticed any increase in accuracy from neck sizing so I gave it up and full length resize everything.
