.300 win mag....to crimp, or no?

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barebackjack
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.300 win mag....to crimp, or no?

Post by barebackjack »

Im loading up some .300 win mag rounds for a guy. I built up a load this summer for the rifle that shoots great. Never had much experience with big cals for hunting. I didn't crimp the test rounds as I wasn't to concerned with magazine issues and bumping or jarring bullets in/out of necks and honestly never gave it a second thought, until now.

Am wondering if crimping rounds for a high recoil gun like a .300 wmag is required or just preference?

Internet search shows a 50/50 ratio for and against it.

Im also wondering if anyone knows just how much a light crimp will increase pressure, im sure it will change things some, but will it be enough to significantly mess with the load ive worked up?

I dont have the rifle in my possession anymore, so cant really test it out.
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Tim Anderson
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Re: .300 win mag....to crimp, or no?

Post by Tim Anderson »

If you are crimping on the canlure then yes it can increase the pressure some. The larger the case the less you will notice or have in pressure spike.. Crimping is needed mostly for revolvers and lever-actions but it would'nt hurt to mark a few rounds and see if the bullet moves when rifle is fired. A black magic marker or Machinest blueing works well for this..
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Re: .300 win mag....to crimp, or no?

Post by lyonch »

Tim Anderson wrote:it would'nt hurt to mark a few rounds and see if the bullet moves when rifle is fired.

Isn't a bullet suppose to move when it is fired :? I sure hope mine move when i pull the trigger :lol: :lol:

BBJ i have no experience in loading larger calibers, but i would personally load them as you did the time before; simply for safety factor reasons. After you get a chance to have the rifle in your possession i would then do some playing around with the crimping process.
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barebackjack
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Re: .300 win mag....to crimp, or no?

Post by barebackjack »

Im not to worried about making it "dangerous". The go to load I worked up is WELL within specs, in fact its on the low side for charge/pressure.

Bullets seemed to seat plenty hard, but I have not a lot of experience with big brass guns so I dont know what it really takes to jar a bullet around in the case.

I know most factory rounds come with a crimp.

I guess ill just load em without a crimp and have the guy shoot a few and see. Can always run em back through the seater and put a light crimp on em.
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Tim Anderson
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Re: .300 win mag....to crimp, or no?

Post by Tim Anderson »

[quote][/Isn't a bullet suppose to move when it is firedquote]

They better not if they are still in the magizine.... :lol: :lol: :shock:
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lyonch
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Re: .300 win mag....to crimp, or no?

Post by lyonch »

Tim Anderson wrote:
[/Isn't a bullet suppose to move when it is firedquote]

They better not if they are still in the magizine.... :lol: :lol: :shock:

If you have bullets moving in your magazine, you have some pretty serious issues going on. Maybe i dont shoot enough large caliber guns to notice anything, but i think the first sign would be that your grouping opens up on you if they are moving back and forth. I dont think i want to sit behind a gun that can move the bullets back and forth as they sit in the magazine :shock:
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Tim Anderson
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Re: .300 win mag....to crimp, or no?

Post by Tim Anderson »

lyonch: This is why some cartridges have to be crimped. Its not limited to just big bores but the type of weapon being used. AR-15 for example with a 30 rd. clip, Auto pistols as well as revolvers, and ammo that is rideing around in a truck all month in a plastic ammo box. (depending on type of box) Vibrations and recoil can cause a bullet in the mag. to move inward or out. Ammo laying loosely inside the truck can also break down the powder into a finer form which can also cause high pressure spikes...
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leadbiscuit
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Re: .300 win mag....to crimp, or no?

Post by leadbiscuit »

Barebackjack,

I've handloaded for lots of other people and think I understand your concern. Having someone else behind the trigger changes things. One thing you might do is measure neck tension. Forgive me if I tell you something you already know. Simply measure the neck of a resized case before and after bullet seating. If you get a difference of .004 or more, you should be fine.
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barebackjack
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Re: .300 win mag....to crimp, or no?

Post by barebackjack »

Thanks for the tidbit lead.

Another person recommended that to me, although they said if over .003" should be good to go.

I measured ten and came up with .0035-.006. Think ill just leave em alone.
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Tim Anderson
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Re: .300 win mag....to crimp, or no?

Post by Tim Anderson »

[quote][I've handloaded for lots of other people and think I understand your concern. Having someone else behind the trigger changes things. One thing you might do is measure neck tension. Forgive me if I tell you something you already know. Simply measure the neck of a resized case before and after bullet seating. If you get a difference of .004 or more, you should be fine./quote]

I'm not sure if I understand what you just said. But you can't measure neck tension. What you are measureing is neck exspansion. How much the case mouth opens after fireing and its dia. after resizeing and seating a bullet..
This measurement is used for checking thickness of necks after fireing a number of times and if you are useing a tight neck chamber.. For a tight neck chamber you want at least .003 for clearence on a hunting load...
If you are useing bushing dies and boat-tail bullets you can undersize the neck dia some what to increase the neck tension, this may or may not affect accuracy, each gun is different..
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Re: .300 win mag....to crimp, or no?

Post by Coyotehunter »

good discussion. I don't crimp my .300 win mag. some powders out gas more than others and a compressed summer load may require crimping as well.
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leadbiscuit
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Re: .300 win mag....to crimp, or no?

Post by leadbiscuit »

Coyotehunter,

Your remark is way over my head. Care to enlighten me ? What did you mean by outgassing and having to crimp a compressed summer load?
Thanks,
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Re: .300 win mag....to crimp, or no?

Post by Coyotehunter »

ever walked into a house with new carpet or paint? the glue and solvents produce a smell as they evaporate. gun powder will do the same thing and more or less depending on the temp. This is refered to as"out gasing". Your powder will expand and contract as well following the ambient temperature. A load that is compressed when seating the bullet can at times expand enough in warmer temperatures to actually push the bullet out enough to change your bullet seating distance off of the lands of your rifleing as you chamber the round. Which in turn can change the impact point. Crimping can eleviate that problem. Hope that clarifies my point a little.
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leadbiscuit
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Re: .300 win mag....to crimp, or no?

Post by leadbiscuit »

Awhile back a fellow showed me some of his handloads. They had been sitting around and the primers were backing out of the brass. I didn't know what to make of it then. Now it makes sense. Thanks.
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