Reloading Belted Magnums

[ISUSteve]

Whats different about reloading for belted magnums?

How many firings do you get per case?

I'm looking specifically at the 300 win mag.

[918v]

Nothing different. Number of firings depends on your chamber, your load, and how you size the case. If you have a tight chamber, use a medium load, and neck size, your brass will last just as long as any other. If you have a factory chamber and F/L size every time, your brass will last about 5 shots.

[Anvil]

I like the .450 Marlin. It's like a 45-70 govt. magnum (and it's belted) Outside of that I don't approve of bottle neck 20 something and 30 something calibers.

They may work great but for me it's got to thump.

[freakshow10mm]

The 45/70 can be loaded to the same 43,500 psi of the 450 Marlin. Use the Marlin 1895 action. The 45/70 and 450 Marlin are identical guns the only difference being the chamber cut. The belt does nothing productive. It's simply the .458x2 inch American wildcat that has been standardized.

[The10mmKid]

Hi Steve,
Hope you join the 300 club.

I've been shooting my TIKKA T3 in 300 WinMag for about 6 mo.

It's another one of those rounds I'm finding that I can load from soft & suttle to outright "damn that hurts" (like my 10mm) :yesnod:

I have only used once fired brass in my reloads thus far.
I FL sized it on my LEE, shot it and now about to go a second round.
I purchased a LEE collet die to size just the neck now that my brass is form fired.

The belt of course determines chamber seating. All you will worry about is bullet seating. The mag on my TIKKA is my COL limiter. I will progress to hand feeding her if/when my accuracy moves to the next level. Right now the T3 & me are still on our honeymoon. :)

The only brass I have more than a few firings on is some tarnished stuff that I trial load and hope to recycle sooner than later. No stress yet.

With neck sizing only, I've read you get just as many reload cycles as any other 30 cal round.

Some notes:
Get ready to buy a lot of powder !!!
(average load is 75gr)
Stay way from hot 200gr loads . . . . . **** that hurts.:cryin:
(matter of fact, I'll send you some boolits to share the pain/love)
Useful cartridge for weeding out your wimpy friends.:animlol:

Enjoy,
The Kid

[ISUSteve]

I don't have one yet. I started with the 300 win mag, then the 300 WSM, then the 338 win mag, then the 325 WSM, then back through all of them again, then the 308. Now I'm back between the 300 win mag. I'm lost.

[918v]

The round DOES NOT headspace on the belt. It headspaces on the shoulder just like any other bottlenecked round.

Belted magnums originate from the 375 H&H which was given a belt because its shoulder was deemed too slender for reliable headspacing. Since then, belted magnums evolved to a point where the belt is completely unnecessary. Factory chambers and factory brass (belt position) vary so much that you have a pretty good chance of seperating your casehead if you were to headspace off the belt as a rule. Don't do it. Follow the standard protocol of turning in the sizing die on a fired case until the bolt just barely closes. This will ensure long case life.

[Steve Koski]

Just sand the belt off with some 1200 grit sandpaper.

[The10mmKid]

Koski . . . . . You have the right answer to everything:animlol:

I was thinking Die Grinder

The Kid

[fredj338]

The belt of course determines chamber seating. All you will worry about is bullet seating. The mag on my TIKKA is my COL limiter. I will progress to hand feeding her if/when my accuracy moves to the next level. Right now the T3 & me are still on our honeymoon. :)
The Kid
Full length sizing of belted cases to headspace on the belt is the best way to shorten case life. The case properly headspaces on the shoulder. If you set your dies up to not push the shoulder back, you'll get just as many reloads as non belted cases.

[craig110]

Full length sizing of belted cases to headspace on the belt is the best way to shorten case life. The case properly headspaces on the shoulder. If you set your dies up to not push the shoulder back, you'll get just as many reloads as non belted cases.

My understanding is that the reason for the belt is precisely for headspace control and so the round doesn't have to depend upon the shoulder position. Take a look at the current American Rifleman, as they have an article about the development of the .375 H&H in it that speaks to this. ("The Beginning of the Belt", American Rifleman, June 2008, page 51.) The article even cites passages from the patents that specifically say that the belt is to control how far the case goes into the chamber.

[ISUSteve]

I think orginally they headspaced off the belt, but now they headspace off the shoulder. I learned this at the gunshop, so I don't know what to believe.

[fredj338]

My understanding is that the reason for the belt is precisely for headspace control and so the round doesn't have to depend upon the shoulder position. Take a look at the current American Rifleman, as they have an article about the development of the .375 H&H in it that speaks to this. ("The Beginning of the Belt", American Rifleman, June 2008, page 51.) The article even cites passages from the patents that specifically say that the belt is to control how far the case goes into the chamber.
That was true for the 375h&h & the 458winmag as they have little to no shoulder for proper headspace. ALL OTHER belted mags w/ decent shoulders should headspace on the shoulder for best accuracy & brass life. You may of course load the way you like.:yesnod:

[MakeMineaP99]

Get a RUM, belted mags SUCK!

[ISUSteve]

thought you liked whisky.

[MakeMineaP99]

That's what I'll name my caliber, the 300 Whisky Express.

[ISUSteve]

It'll Make 'er Mark

[ronterry]

Explain how the .300, .338, & 458 Winmag's share the same headspace gauge?

I do agree the shoulders play a huge role like one's which are to high wouldn't allow the belt to headspace properly, but on the technical the headspace on belted cartridges is measured from the bolt face to in front of the belt.

BTW: I have ten firings to date using FL X-dies in .338 Winmag (Winchester brass). Only fired in a stainless Browning A-Bolt boss. Loud & obnoxious with a very nice pressure wave (i.e. invisible slap in the face to the guy sitting next to you at the range). I also anneal the necks every couple of firings. Can't wait to see how this brass finally lets go?
I've taken them to edge a few time, but the rest was fine tuning for accuracy somewhere in the mid range.

[918v]

Explain how the .300, .338, & 458 Winmag's share the same headspace gauge?

What does that have to do with the variance in the position and thickness of the case belt between different brands of brass?

FL dies are designed to size a case to fit a minimum chamber. If your rifle has a maximum chamber, and your particular brand of brass has a thin belt, and you end up with .020" of headspace, your casehead will let go. Many belted mag shooters found that out the hard way.

[ronterry]

As long as the distance between the bolt face and the front of the belt (i.e. Headspace) is with in publish specs it's not about the GUN. We can cross are fingers and hope the belt and shoulder are proper on the reamer :)
That's all I was trying to say.
My X-dies & Win brass are serving me well, and with ten firings they show no sign of giving up anytime soon. Knock on wood!!! I bet I get a case-head next range out.

[Clark]

I think that the first time a 300WM is fired, it is supposed to react to firing pin force with the belt, and then when resizing it, you don't push the shoulder back, and following shots have the shoulder resisting the firing pin push.

I have a 300WM reamer with such a belt feature, but I go in with a tiny lathe bit and cut the belt relief .005" deeper into the chamber, so I can headspace on the shoulder for the first shot. That relief can be .220 to .227" per the SAAMI tolerance drawing, so I still meet SAAMI specs at .225".

The brass can be .212 - .220".
.227-.212" is the .015" of permissible slop that 918V is writing about.
This amount of slop would be a big deal in .223 or .308, but just part of ruining brass in a 303 Brit.

Some people are really disgusted with me for taking that first shot off the shoulder.
I do it for more accuracy, but the accuracy seems to be the same either way for me.
Bart Bobbit has some things to say about this in the 15 year old archives.

[918v]

Supposed to...

That's the problem. Excessive headspace won't kill a case on the first firing, but it will cripple it. Subsequent improper loading will further weaken it, ot kill it altogether.

[fredj338]

As long as the distance between the bolt face and the front of the belt (i.e. Headspace) is with in publish specs it's not about the GUN. We can cross are fingers and hope the belt and shoulder are proper on the reamer :)
That's all I was trying to say.
My X-dies & Win brass are serving me well, and with ten firings they show no sign of giving up anytime soon. Knock on wood!!! I bet I get a case-head next range out.
Then count yourself fortunate, it's not the norm.

[craig110]

Then count yourself fortunate, it's not the norm.

If the brass is always shot from the same gun, only has its neck resized after the first loading, and isn't used in upper-end loadings, what do you consider the norm to be for long the brass will last?

[918v]

I think he's talking about FL sizing every time, bottoming out the die, and hoping the belt will save you. It won't.

[craig110]

Ok, but my question still stands since I'm looking at getting into .375 H&H in the near future and am curious about how long I can expect the brass to last.

[MakeMineaP99]

.375 H&H is old school. Get a non belted mag, like a .375 RUM. Belts suck and don't serve the purpose they were created for (as we've gone back and forth about in the proceeding). Also keep in mind, match bullets, SMKs especially, only go up to .338, I don't know what you're planning on doing.

[craig110]

.375 H&H is old school. Get a non belted mag, like a .375 RUM. Belts suck and don't serve the purpose they were created for (as we've gone back and forth about in the proceeding). Also keep in mind, match bullets, SMKs especially, only go up to .338, I don't know what you're planning on doing.

I'm somewhat limited to the calibers available for the TC Encore line, and they don't have a .375 RUM.

Now, what am I planning on doing? Occasional fun shooting at the range. I've realized that I don't have the spare time to get seriously into 600-yard shooting, so I've been looking at a caliber path that would include .308 for my normal target shooting and .45-70 and .375 H&H for fun thumping. The notion that .375 H&H is old school doesn't bother me. Actually, I've also considered getting into black-powder and, if the lesser guns make me feel that I'm up to the recoil challenge of an occasional trigger pull, the .416 Rigby. I like the freedom that reloading gives to shoot some of these unusual, historic, and yes perhaps somewhat outdated, calibers. (I'll likely only shoot cast bullets out of these as well.)

As to belts sucking, what I've seen in the discussion above is confusion over how they headspace and whether belts do anything useful on calibers after the .375 H&H, but I haven't seen anything that says that the belt is useless on the .375 H&H.

[ISUSteve]

Calm down kids or i'll get the belt after you

[918v]

Ok, but my question still stands since I'm looking at getting into .375 H&H in the near future and am curious about how long I can expect the brass to last.

If you FL size, bottom out the die against the shell holder, and use maximum loads, your brass may not survive three firings. Do whatever you can to keep the case flush against the breechface. That will maximize case life more than anything else. No one can give you a reliable number. Ideally, you should get 30+ firings out of a minimum match chamber, if you neck-size, anneal, and use moderate loads.

[Washington,D.C.]

For a 30 caliber belted magnum 30-338 is one of my favorites.

[craig110]

Tell us more. Why is it your favorite and what others have you shot?

[freakshow10mm]

Craig, if you get into the 375 H&H, I have several hundred OF brass if you are looking for some to get started. Two of the best molds to buy for the Holland are Lyman's 378674 (335gr RN) and the 375449 (264gr FNGC; 275gr w/ WW). My Encore barrel (was a rifle cut down) slugged at .375 so .376 die should be good.

I bought a CZ550 stock and .375 Holland barrel off Tailgunner recently. When I get my 07, I'm going to build it back up but thinking of chopping it to 20" for a close range blaster.

Get a neck sizer die. You can also ream the chamber to the Ultra Mag. I've looked at the 375 Dakota too and love it, but brass is pricey.

[craig110]

Thanks for the mould info and the brass offer, Freak! Do you need any .270 brass? I have 370 of them on ammobrasstrader and had a nibble, but no takers yet.

[fredj338]

If the brass is always shot from the same gun, only has its neck resized after the first loading, and isn't used in upper-end loadings, what do you consider the norm to be for long the brass will last?
I had a 7remmag that I could easily get 10x-15x with partial FL sizing. The same should go for your 375H&H. Set your FL sizing die so it only partially sizes the entire case & try to cahmber it. Keep turning the die down until is just chambers w/ some ease. That is your sweet spot & you should get pretty good brass life. The long, sloping case of the H&H rounds will require trimking every 3-4 firings though.

[craig110]

I had a 7remmag that I could easily get 10x-15x with partial FL sizing. The same should go for your 375H&H. Set your FL sizing die so it only partially sizes the entire case & try to cahmber it. Keep turning the die down until is just chambers w/ some ease. That is your sweet spot & you should get pretty good brass life. The long, sloping case of the H&H rounds will require trimking every 3-4 firings though.

"Partial FL sizing"? I've never heard of that approach before. Are you shooting all of your 7RemMag from the same gun? If so, why do the cases not fit back into the chamber with only a neck sizing?

[freakshow10mm]

It's like an in between FL sizing and neck sizing. You essentially resize only the softer upper portion of the case while leaving the harder portion untouched until it doesn't chamber. Then FL size. Doing this sets the bullet tension.

[craig110]

It's like an in between FL sizing and neck sizing. You essentially resize only the softer upper portion of the case while leaving the harder portion untouched until it doesn't chamber. Then FL size. Doing this sets the bullet tension.

Maybe I need another cup of coffee on this rainy morning, but I still don't get it. For a sloped cartridge like the .375H&H, the FL sizing die would be equally sloped on the inside, so how can only the upper part of the case be sized without the bottom being sized? (Imagine fitting an equilateral triangle into something with has an equilateral triangular cutout of the same size. If you put the triangle directly into it, none of the edge will touch until it all touches.) Or is it that the softer upper portion expands more and so it is "sized" only enough to bring the upper portion's amount of oversize down to equal the bottom portion's oversize?

Either way, I thought that fire-formed cases would always fit back into the chamber it was fired in and that neck-sizing is what sets the bullet tension. :confused:

[freakshow10mm]

Or is it that the softer upper portion expands more and so it is "sized" only enough to bring the upper portion's amount of oversize down to equal the bottom portion's oversize?
Pretty much.

that neck-sizing is what sets the bullet tension.
Yes, and in the FL sizing die when partial FL sizing, the expander plug fits into the neck, creating the bullet tension.

I'm sorry I'm having a hard time explaining it. Fred or TG are better at it than I. TG is the one who told me about it.

[craig110]

I'm sorry I'm having a hard time explaining it. Fred or TG are better at it than I. TG is the one who told me about it.

No problem as it seems like a rather bizarre thing to try to explain! Hopefully they will chime in here.

[Brass Nazi]

<--------- Almost always partially full length resizes rifle cartridges.



Most reloading manuals explain partial full length resizing.

[Tailgunner]

No problem as it seems like a rather bizarre thing to try to explain! Hopefully they will chime in here.

Craig, your on the right track with your "triangle" thinking, but your forgetting one variable and that's the amount of compression being done to the case body/shoulder location.

To put some example numbers to things, let's say that factory ammo has a shoulder diameter of .400 at the shoulder, and the shoulder/body junction is at 3.000 above the base. After firing that ammo in YOUR rifle, you find the shoulder diameter is .420 and the location is at 3.050.
Now, with your FL die set to "contact" the shell holder, it will return the brass to it's factory dimentions (full length sizing), but by raising your die by .060 above the shell holder, your shoulder will stay in the same location, your shoulder diameter will end up at .415 and enough of your neck will be sized to hold the bullet properly. Or you could raise it by .049 and just bump the shoulder back a thou and bring the diameter back down all the way. Either would be setting it to do a PFL sizing (note, I'm pulling the numbers out of my ass, they are just for examples).

In a BM (that's some kind of movement isn't it?) headspace is (in theory) controled by the belt, considering that the spec for the chamber recess is .220-.227 and the spec for the cartridge belt is .212-.219 you can see that having as much as .015 slop AT THE BELT is still "in spec". When you add in the fact that the shoulder location and diameter are NOT considered critical (they are critical in a rimless design), you can see where the case will get worked a lot in the shoulder area (the belt slop is the primary reason for short case life). With the PFL, you actually making the case headspace on the shoulder and for all intents treating it like a rimless design.
Mil-Surps with their typical sloppy chambers are another prime candadate for PFL sizing.

[craig110]

Thanks, TG, that explains the mechanics of PFL sizing nicely. I still don't quite get the "why?" since it would seem that the fired case should be able to fit back into the chamber with just a neck-sizing to hold the bullet, but perhaps this will all make more sense to me when I get the .375H&H and have direct experience with what happens to the cases.

[Tailgunner]

Assuming the chamber is round and concentric, it will rechamber with just neck sizing BUT with neck sizing you still need to bump the shoulder back every few firings, to do that you either need a FL die, or a body / shoulder bump die.
Another way to look at it is: PFL is a CRB way of neck sizing, without having to purchase any extra dies.

You'll notice that I never recogmend setting (any) bottleneck dies up to hit the shellholder, but instead to adjust them to the point where the bolt just closes on a sized case.

[craig110]

Another way to look at it is: PFL is a CRB way of neck sizing, without having to purchase any extra dies.


Now you're talking my language! :thumbsup: :rofl:

Actually, it does make sense now. Thanks!

[Brass Nazi]

You'll notice that I never recogmend setting (any) bottleneck dies up to hit the shellholder, but instead to adjust them to the point where the bolt just closes on a sized case.


Bingo.

[Shibumi]

Sorry about the resurrection, but my brother just commissioned me to reload for his .300 Win mag (bolt gun). If I may synopsize to make sure I understood all this, and please tell me if I effed it up...

- It is safe to simply neck size this round, and get 2-3 firings out of it before having to worry about trimming, or adjusting shoulder.


He is having me duplicate the spec for the Marine sniper and 1000 yard round using Sierra MatchKing 190 grain bullets and RE-22. He wants to explore the extreme limits of long distance shooting with it, and use it (with a different bullet of course) for African plains animals.

Any tips on reloading for accuracy with this caliber?

[freakshow10mm]

Accuracy is the product of uniformity.

Beyond that I can't help ya with the .300 Mag. Sorry.

[craig110]

Accuracy is the product of uniformity.


A lot of wisdom is contained in those six words. Everything I've read about reloading for long distance and/or benchrest shooting boils down to having each round be an identical clone of all its brethren. The challenge is that their definition of "identical" is very different from what standard reloaders use.

[ISUSteve]

In other words, you're looking at dumping more money in reloading equipment.

[Shibumi]

In other words, you're looking at dumping more money in reloading equipment.


Even better, HE buys all the toys and I get to play with them!! :yesnod:

So we have a mutually satisfactory situation.