Reloading Belted Magnums (.300wm)

Boomer686

Boomer686

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Just getting into .300WM now after reloading and shooting .223, .308 & .338LM for quite some time.
What dies do you recommend for this cartridge? My other dies are all either Dillon or Redding (or mixes of each).

Firearm is the new Browing X-Bolt Hell's Canyon MacMillan Edition 7 the plan is to develop a good ELR load for both hunting and shooting with
212gr Hornady ELD-X bullets using either H1000 or H4831SC as I have lots of both.

Thoughts?
 
First few thoughts are that your rifle will tell you what it likes. Your component choices are a good start.

I have been switching to Redding. Since you reload 308 already i will make some assumptions. You have preferences for brass and primer, you have other 30 cal projectile available, and you have other faster powders.

Without looking at my loads, H1000 seems a bit slow.

Welcome to the rabbit hole.
 
I use a Lee collet neck die, Redding Body Die, and Forster Seater.
I had been using H4831SC, but recently did some load development with H1000 that showed improvements using the same components (Berger 210 VLD's, PRVI Brass, and CCI 250 primers).
Try both powders, you already have them.
 
Rabbit hole for sure! I'm not worried about load development and that as I got lots of time punched on various calibers already over 30 years of shooting and close on that time as well for reloading.
Just never reloaded belted magnums before and was wondering if there was anything in particular with regards to dies that work better / need to watch when processing the belted mag brass.

Thanks,
 
While I haven't tried H-1000 yet, I intend to get some; its the go to powder for too many .300 Winchester enthusiasts shooting bullets heavier than 180 grains, to be ignored. In my rifle H-4831SC, IMR-7828, and R-22 all do well, but H-100V that I've used successfully in the .375 Ultra, the .270 and the .30/06 proved to be a bit quick, and showed high pressure before I got the velocity I hoped for with 180s. H-100V, falling midway between 4350 and H-4831, might do well with 150s, but I don't shoot bullets that light in my .300.

All of the die boxes on my bench are green, with RCBS and Redding being equally represented. Belted bottleneck cases should be resized just enough to ensure effortless cycling through the rifle, while ensuring it head-spaces on the shoulder rather than the belt after its initial firing.
 
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H1000 is pretty much the go-to powder for 300 wm and heavy projectiles. 7828 is decent too. Retumbo can give slightly better speeds sometimes but its a little on the slow side for 300wm. I think the H4831 might give you better speeds in the 180 and under class. Don't think you'll have any issues with any die you choose. I like using a Lee collet neck die after partial- full length bump sizing. That way it always runs right at 0.002" of neck tension. The Lee C.N.D. is pretty well priced too, maybe in the neighborhood of $30. Ill look up my notes on where i hit pressure and at what velocities with the 212's and send them along for your reference.


Also Remington brass seemed to last the longest for me(way more than Federal or W-W), dunno if anyone has any experience with Privi Partizan or Peterson? They seem to have potential.
 
I have reloaded for the .300wm a bit. I have found that there is a slight problem that might occur depending on your chamber. Mine I have the problem that the area around the belt is not resized and in some rifles the case will not chamber after being reloaded. As the area around the belt is not touched when being resized. some have the problem and some don't. I found that with the Browning rifles I reloaded for, they would chamber on first reload in mine but the cartridge would not chamber in my hunting partners Rem. or Ruger.
They would not chamber at all after second reload.

I found this on the web to explain the problem and they also sell a die to help cure the problem. ww w.larrywillis.com.

Like I said you might run into this and you maynot if you do this die seems to cure the problem.
 
Boomer686 said:
Just getting into .300WM now after reloading and shooting .223, .308 & .338LM for quite some time.
What dies do you recommend for this cartridge? My other dies are all either Dillon or Redding (or mixes of each).

Firearm is the new Browing X-Bolt Hell's Canyon MacMillan Edition 7 the plan is to develop a good ELR load for both hunting and shooting with
212gr Hornady ELD-X bullets using either H1000 or H4831SC as I have lots of both.

Thoughts?
Click to expand...

I use the Lee neck collet for initial neck sizing. I have a Redding body die which works for the most part initially as well, but eventually I found I needed a Larry Willis Belted Magnum Collet Die to resize the body fully.

I like neck turning once I have brass fully fireformed and trimmed to length. I have to pick up a 300WM case holder from 21st Century. Neck turning is an option I like to do. It is certainly not required and the Lee neck collet is really all that is required for that aspect.

I use a Redding Competition seating die.

I have only used H4831SC since I had an 8lb jug. I might give H1000 a try some time in the future, but until I get low on it, the 4831 works for me.
 
wce323078 said:
I have reloaded for the .300wm a bit. I have found that there is a slight problem that might occur depending on your chamber. Mine I have the problem that the area around the belt is not resized and in some rifles the case will not chamber after being reloaded. As the area around the belt is not touched when being resized. some have the problem and some don't. I found that with the Browning rifles I reloaded for, they would chamber on first reload in mine but the cartridge would not chamber in my hunting partners Rem. or Ruger.
They would not chamber at all after second reload.

I found this on the web to explain the problem and they also sell a die to help cure the problem. ww w.larrywillis.com.

Like I said you might run into this and you maynot if you do this die seems to cure the problem.
Click to expand...

I've bought his collet die, I've never used it though for a 257 Weatherby. Maybe I haven't had enough reloads out of the cases yet.


diesmall.jpg
 
I load for the 300wm.
The lighter the bullet the faster burn rate powders work better.
Try Rl-22 for 180-200gn, H-1000 for the heavies.....even then 210gn bullets can use a powder a little slower than H-1000.
For targets and banging steel I use a Federal 210M primer, get better ES and have had no problem lighting them off in sub zero temps.
As others say a body die (shoulder bump), Lee collet die, and a regular seating die with an optional VLD seater stem. Also have a regular size die on hand.
Shoulder location on belted cases are not very consistent, easy to see 0.008" variance. They still rely on the belt for proper headspacing.
To get the most out of your brass it is prudent to neck up 10-20 thou then then run into the regular size die to form a false shoulder ( an 8mm mandrel will work) , then fire form the brass. Otherwise you may 'stretch' the case up to at least 8 thou depending on the chamber, thus reducing the overall life of the brass.
 
If you can get your hands on some, Reloder 25 or 26 work well with heavier bullets in the 300 Win Mag and 308 Norma mags.
My latest 308 Norma gets 3005 fps average with the 200 Partition and Reloder 25. Dave.
 
I’ve been using my rcbs FL dies and 7828 powder for my Browning SS 7 mm.

If I remember correctly, I was having an issue with a couple of case head separation.
And I could see the ring around the bottoms of the cases.

If I recall, this was due to over sizing ( overworking)or doing a complete FL sizing.

Once I backed my dies off a bit ,all is good now:)
 
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I use H1000 almost exclusively in the .300 WM and seldom bother with bullets under 180. Come to think of it, I don't spend much time with bullets heavier than 190 either.

For the most part I size the cases the same as anything else; bump between .000 and .002" with the Redding Comp shell holders. The little bit of chambering issues I've had have been man-made. Some was from head spacing super short, with extra small reamers. The rest were usually some variation of useing brass from another generously chambered rifle. In other words, looking for trouble.

I've got a small base die and the Willis tool, but they don't get much use that can't be traced to the above. Theres millions of belted magnums that are loaded with no problems all.
 
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Big fan of the Lee collet neck die, Redding body die, Forster seater combo. Let the barrel tell you which bullet it wants to shoot.

There are many new accurate high BC bullets in the 195 to 200gr class. For ELR shooting, super fast speeds doesn't change the outcome. Tune for moderate pressure and the most consistent accuracy.

at these moderate pressures, the area around the belt is less likely to bulge (alot also depends on the chamber dimensions) which is what cause shooters alot of grief. When that happens, just toss the brass. An unsupported area in the chamber will let the brass bulge... oversizing can cause the case to split. I would rather just toss the case and save any headaches.

sounds like a nice rifle.

If I can help with optics, I have a couple of great options with 190 to 200MOA of available adjustment (mil versions possible too) using reticle and scope travel. Tested these out to 1820yds with excellent tracking and repeatability. They don't cost a fortune either.

Jerry
 
I agree with the above.

My own $0.02:

Interesting problem. If you have a mic or a vernier, could you measure the belt. I've owned 3 Win Mags and the chambers can be a bit funky.
It sounds like your chamber is a bit tighter than it should be in the belt area. But, in reality, the belt of a magnum case shouldn't expand much, if any.
An old school max load guide was to stay below 0.001" expansion at the belt. That was revised to 0.0001 later. I haven't seen that method of load testing for some time, just mention it to back up the amount of expansion expected.

I just got out the mic and checked some new cases, 0.529", and once fired, the same. SAAMI minimum chamber spec for the belt diameter is 0.535 + 0.012', max ammo is 0.532" - 0.005.

The Larry tool targets the web area, just ahead of the belt. This area is not sized by the die, but in most instances, this is of no consequence because the case does not expand until about 0.050" ahead of the edge of the belt. You may want to measure your cases in that area. Some refer to it as the pressure ring.

This is the area that, normally, never touches the chamber and is not sized by the FL die. I use this as a quick visual indicator that pressure is not excessive. This ring will get narrower the more it is fired, but if it disappears, you'll need the Larry tool. I personally do not hotrod my magnums. If this ring gets too narrow, I reduce my load. Accuracy usually happens at less than max pressure.

jKLZX64.jpg


I realize that this doesn't solve your problem. Take some measurements and do some visual checking, sorry, that all I can suggest. Posting pictures helps.
 
Ganderite said:
The case will headspace on the shoulder (not belt) if you don't over size the case. This will get you better case life.
Click to expand...

That pretty much sums up the issue with most belted magnums.

I've had some issues with magnums in the past. At the core, the belted magnum case was designed to have the reliability of a rimmed or flanged case, yet feed from a magazine like a rimless cartridge. Belted magnum brass is spec'd at being from 0.220" max to a minimum of 0.212". The chamber headspace is spec'd at being 0.220" min and the max is 0.227". Theoretically a minimum cartridge would have 0.015" headspace clearance in a maximum chamber. For arguments sake I'll use a 458 Win Mag as my example. In spite of it's issues, I don't think a 458 Win Mag has issues with not firing.

The 45-70 has similar min max specs for rim and chamber.

I conclude that historically, this somewhat loose headspace possibility was to allow for less than ideal field conditions, dirt, heat and ugly ammo, and still ensure reliably. No jams or FTF.

Fast forward to the modern magnums, the ones with fairly straight walls and a shoulder in the 25 > 30 degree range. If you examine the specs for the shoulder distance, what in a rimless calibre would be the headspace, it gets a bit funky. There doesn't seem to be an exact standard, but the case shoulder min to chamber max spec is 0.025" for the 350 Rem Mag. Other magnums are spec'd similarly.

Factory ammo will work OK in a factory rifle. The big problem for the die manufacturer is what spec do you build the FL sizer die to. You can't do anything with the belt, but with 0.025" of latitude what spec do you make the FL die to. If you make it to min case spec, all the ammo sized by it should fit every factory rifle. My 350 die was like that. I bought a +0.023" shellholder from Redding (in stock coincidentally, or perhaps not a coincidence at all). My other die didn't have that issue.

In rimless cartridges, when the headspace clearance approaches 0.010", incipient head separation is just about guaranteed. But because rimless calibers rely on tighter headspace clearance to function, the tolerance range is smaller. In a modern non belted magnum like the 270 WSM, the case min to chamber max is 0.013".

As reloaders, we have to live with these tolerances. For reliability you need to have a single factor for controlling headspace, which in a belted magnum is the belt, so the ammunition spec moves the shoulder back out of the way, and in the chamber it moves the shoulder forward out of the way. Min or max, the cartridge will never headspace on the shoulder, it will always headspace on the belt, (new ammo/new rifle).

I adjust the FL sizing process for my belted magnums to give me at least 0.003" shoulder setback, and no more than 0.006" setback. As mentioned earlier, for one die it meant buying a +0.023" shellholder and for a certain 7mm Rem Mag, I had to grind a few thou off the shellholder. I once tried to adjust the die, it hit the garbage, I'll not grind the bottom of a die again. It doesn't take much before the die will begin to create a pretty funky step in the belt.

I like this article http://www.sportingshooter.com.au/news/belted-magnums-still-the-big-game-hunter-s-friend
 
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