belted vs non belted magnums????

[186thFCo]

Can someone please explain to me the advantage or disadvantage of having a non belted magnum cartridge (performance wise). I see on here every now and again people say they have a problem with belted magnums like the 300 WM but I don't remember seeing them explain why they feel that way.

The reason I'm asking is because I'm going to be building a new toy and i want to make the right choice for a magnum cartridge.

 

[Ledzep]

Non belted magnums typically stack/feed better out of detachable box magazines. Also, you're typically looking at more internal volume in a non-belted magnum for the given case diameter/length. Another thing to look at is headspacing off of a shoulder or a belt and reloading/resizing to get the headspacing you want on your ammo. I'm sure there's more.

 

[186thFCo]

Non belted magnums typically stack/feed better out of detachable box magazines. Also, you're typically looking at more internal volume in a non-belted magnum for the given case diameter/length. Another thing to look at is headspacing off of a shoulder or a belt and reloading/resizing to get the headspacing you want on your ammo. I'm sure there's more.

Ok I understand case volume, but I don't get any resizing problems. I have a 7mm rem mag, and I just use a use the FL resizing die, back it off a bit and just to bump the shoulder back a few thousands of an inch. Wouldn't that be the same process if the cartridge is a 7mm RUM?

And as far as feeding from a box mag goes, I haven't any issues with my 7mm.

 

[brianf]

belt or no belt there is no difference, its just one more measurement that you have to be aware of when reloading. its still amount of powder = pressure = bullet FPS.

if you are not going to reload it makes absolutely no difference.

its when people reload:

The main problem with handloading the 300 Win Mag or any belted magnum is case expansion that occurs at the pressure ring "just above" the belt. regular resizing dies dont resize a belted magnum case in this area.

cases develop a slight bulge around the case. then usually what happens is that a guy goes to the range and his rounds wont chamber because the case is too fat above the belt. he then blames the EVIL belted case rather then understanding that he has something else to measure.

the problem comes in when reloading and people dont get a collet die. a collet die (there are several types on the market over the years) is like a sleeve that goes all the way down to the belt ensuring case uniformity.

there is no secrete, just people who listen to guys at the range instead of read from the pros. LOL

David Tubb (IE best ever) uses collet dies when he reloads belted stuff, that says enough to me (never mind my own experience).

that being said there might be a better cartridge out than a current belted magnum cartridge, so this might not be a real issues once you make a decision.

 

[steve123]

Because I needed to use a Larry Willis/IT die with the 7mmRM after the 3rd firing. Which was an annoying extra step in the reloading process. Otherwise I would have had to throw the brass out or cull the tighter fitting ones to toss the next firing. Maybe my sizer die didn't size the brass down far enough for that chamber, likely. Regardless i'm done with belts.

 

[Deleted member 10043]

.375 and .300 H&H are the only ones that need the belt to support the web area. Their successors have the belt for no apparent reason. Bulging on the web is normal wear and tear on the H&H. You won't see as much bulging on other belted mags because they headspace off the shoulder. But it may still be a problem with today's brass quality and getting them up to a decent MV.

Be advised that the Willis die has a gauge on top to determine if the bulge need resizing. Don't buy this thing unless you are actually experiencing this problem and not just because Tubbs is using it. Just toss the brass if it is already close to being retired.

I only reload the H&H but if I got a different mag it would be without the belt.

 

[FatBoy]

The biggest issue with belted mags IMO is the brass, but I have had pretty good luck with Winchester Bulk in my 300WMs. I have to disagree on one small point, and that's that 300wm being headspaced off the shoulder. On the initial firing the 300wm shoulder is about .020" off in a SAMMI chamber.(A191, etc) After that you can co-headspace. Caveat is if you spec a reamer specific to your brass( and bullet ideally) up front than I agree but not many do this.

As to the collet dies, I don't use one. Not saying they are a bad idea, but the Redding body die is generous in the belt area so we turned about .020" off. This allows me to size down to the belt and set shoulder HS at .005"-.006". It allows me to shoot 230s at 2775 I've got five or six firings on the brass with no issues. The feed like they're new and still hold primers and neck tension.

Belted mags aren't much/any different than a non-belted. They just aren't envouge right now, I figure because the love for short actions and the way WSMs and RSAUMs were marketed.

One thing to keep in mind is brass availability. You can almost ways find 300wm brass and loaded ammo on the shelf. Not the same with the short action magnums.

 

[brianf]

FatBoy, i agree 300 wm seem to really like the Winchester brass. so much so that i use a initial old school load of IMR4350 in winchester brass shooting a 200g SMK.
if i cant get that to shoot low ES and bug holes something is wrong with the gear.
its also a good load for guys that dont need the biggest and best BC or that are getting started because the 200g sierra game king almost has the exact shape and almost exact BC, so while they are practicing at the range they are also practicing for the hunt.
my favorite is RWS brass for the WM. hard to find and you have to drop a few grains because is thicker but i get double the reloads and can push harder

 

[orkan]

David Tubb (IE best ever)

 

[186thFCo]

Redding body die is generous in the belt area so we turned about .020" off. .

What do you mean by this, did you put the die in a lathe and turned it down that way?

 

[FatBoy]

What do you mean by this, did you put the die in a lathe and turned it down that way?

Yes. The area of the die recessed for the belt was very "tall" from die mouth up so we put it in the late, cut .020" and re-chamfered the mouth.

 

[buffybuster]

It really isn't a brass problem or die problem, but a problem of mismatched tolerances. The belted magnums headspace is set by the belt and not by the shoulder (as in other bottleneck cartridges). As a result the shoulder of most magnum chambers (especially OEM chambers) is not as tightly controlled as in other bottleneck cartridges, since the shoulder in a belted magnum is not a critical dimension. The first firing of the belted case the case headspaces on the belt. Then most reloaders set their FL sizing die for maximum caselife and set against the shoulder. The belt is now irrelevant, since the headspace is set on against the shoulder. The issue then is the sizing die does not go down to the belt and an area above the belt is left unsized. After a few firings this unsized area becomes too large to chamber easily in the chamber, resulting in hard chambering or more likely hard extraction (begins with clicking upon opening the bolt). What to do about that unsize area above the belt?; You could turn down the FL sizing die to size down to the belt (might have to shave the die to do that) but then it really pushes the shoulder back, your caselife suffers and you're back to headspacing on the belt. The other solution is to buy Larry Willis die or some other collet type die to size that area above the belt.

That was how it was until the arrival of non-belted magnums (WSM, SAUM, RUM, RCM, etc) Most current reloader's don't think it's worth the hassle, since there are other non-belted magnum cases alternatives.