Need help with Reloading 300 Win. Mag

[alan98]

Hello, I'm still learning about reloading..I've been loading .44 mag for awhile now, and am now ready to venture onto my 300 Win. Mag. I recently purchased 250 once fired brass. I haven't ordered my die set yet as i have a few questions.

I read some people recommend to only neck size, and some say full size, while others recommend to use a full size die, but back it off and only use enough till it just chambers in rifle to avoid pushing shoulder too far back. Which is the best method to do?

I wasn't aware that the belted magnum cartridges are a little bit more challenging to reload, and offer a less than desirable case life. I see a lot about the case above the belt expanding too much after only 2-3 reloadings making the case useless. How is this problem addressed?

How long will the average case (Win headstamp) last for me? 4 reloadings? Just trying to get an idea.

I will be using 190 gr. Sierra Match Kings with H4831 powder and Fed 215 primers. How well does the H4831 perform for the 300?

Sorry for a long first post, but I'm ready to get things started, but can't seem to find the best way to reload this caliber.

Thanks for any help

 

[Jim Watson]

Since you are starting with brass fired in a different rifle, you should probably full length size or size most of the way in a full length die until the brass will chamber freely.

After firing, I would then continue by sizing until it chambered in YOUR rifle, but no more; setting it to headspace on the shoulder instead of the belt.

I can't predict brass life. H4831 will serve well.

 

[rcmodel]

If the brass was not fired in your chamber, I would full-length size them at least the first time.

Since all the belted mags headspace of the belt, not the shoulder, there will not be a problem, even if you do push the shoulder back slightly.

After they have been fired in your rifle, you can back the die off slightly and only neck-size if you want too.

If loading for hunting, I would still want them full-length sized just to make sure you don't get halfway up a mountain and find out your bolt won't close on one of them.

I would think by the time the belt expands enough to cause a problem, your primer pockets would have went south with them, and the cases are done for.


rcmodel

 

[dakotasin]

I wasn't aware that the belted magnum cartridges are a little bit more challenging to reload...

they aren't.

...and offer a less than desirable case life.

maybe true, maybe not. if you load for ragged edge velocity, case life is short - but is so w/ about any cartridge. good solid loads that don't push it too much should be good for 5-7 loadings - possibly more.

I see a lot about the case above the belt expanding too much after only 2-3 reloadings making the case useless. How is this problem addressed?

there is somebody who makes a die to specifically address this problem, but i haven't needed it myself so have no first-hand experience w/ it.

Since all the belted mags headspace of the belt, not the shoulder, there will not be a problem, even if you do push the shoulder back slightly.

after you have fireformed cases to your chamber, you should be headspacing off the shoulder, not the belt, to get best life and accuracy.

 

[alan98]

Thanks for the help....So i will just need to order the full length die and then back it off some after the first firing to only partial size. Correct?

Thanks again

 

[Shoney]

Once the cases are fireformed, you should size cases to just chamber, thus head spacing off the shoulder, or perhaps more correctly headspacing off both the belt and the shoulder. Pushing the shoulder back will cause the case to stretch forward. The stretch shows most in the area just above the belt and in time will become thin, thus causing case head seperation.

To detect this stretch, you can make a simple tool. Straighten a paper clip, then bend about a 3/8" L on the end and sharpen it to a point. Insert this into the case to the bottom. Drag it up the side of the case. If the case is forming a thin ring above the belt, you will readily be able to feel it.

After years of loading the 300WM, I have settled on the 200gr bullet for all around shooting, as it gives the best trajctory and retention of energy out to 500+ yards.

 

[alan98]

Ok, when people are saying to size cases by chamber, that is by using a full length die and backing it off just until the bolt will close? is this right? I'm just a little confused by this..wouldnt using a neck size only die after theyre fired do the same thing? Sorry..i'm just new to all this and wanna do it right the first time

 

[GooseGestapo]

Alan;

You're making this harder than it has to be.

Yes, and no........ The brass has a "memory", and after 2-3 firings and neck-sizeing only, it'll still get hard to chamber and require resizing in a regular sizing die. Some of the difficulty in chambering will be from the "body" of the case expanding to the full size of your chamber. By only sizing to your chamber, means the critical length from the bolt face to the shoulder of the chamber. This is where the stretching occurs that you want to avoid. By reducing the body everytime, you ensure that the case WILL chamber when you need it too....

Just get the regular full length size die. If much later, you decide to go after maximum accuracy, then, get you a "neck size only" die. I suggest the Lee Collet neck size die. I've got several, but honestly, all I load for are "Sporter" rifles. In the single instance of a "match grade" barrel on a .257Roberts, It still prefers to have ammo loaded from the "standard" Lee Full-Length dies, but only sized to "touch" the shoulder of ammo fired previously in that rifle. Hence, the neck-size dies are of limited use.

I think you'll find loading for the .300winmag to be as, or easier, than loading the .44mag as you don't have to expand/flare the case mouths before seating. Nor will will you want or need to crimp, unless you are loading for a Browning BAR.

However, do get the Lee Case trimmer and either the RCBS or Forster neck/case mouth chamfer tools.

After the case prep and first firing, you'll find most likely with "accuracy" loads (meaning something between starting and max. but less than max) you'll find case life of the .300mag to be similar to many other "normal" cartridges such as .30/06 or .270wcf.

trim whenever the case lenght reaches max., and toss the cases after the second trimming.

I've still got some Norma .30/06 brass from a quantity that I bought in 1975 and used to kill my first deer with...... Some has been loaded over 50 times and are still the "best" brass I've ever had for that rifle. (After buying primer pocket reamer, flash-hole reamer, and neck turners, I found out why this brass was the best...... besides the metallurgy. !!!!).
Brass well taken care of can last a long-long time.....

In a friends Sako 75 in 6mmPPC, we deduced that he gained approximately 0.1" improvement in using a Redding bushing type Bench-rest match neck sizing die over a Standard set of Lee full-lenght dies. BTW, this was a reduction of 0.35" to 0.25" ctc for 5 shots. I doubt seriously that you will see any difference with your "Sporter grade" .300winmag. by using a Neck-only size die.

 

[neolithic hunter]

if it is a deer rifle full length size it. if its a target rifle then neck sizing will work. simple. nuf said.