I was wondering what purpose the belt serves on a magnum case such as a 7mm or 300 win, if it is for head space then why do most people wanna head space on the shoulder when relaoding these.

You want to head space on the shoulder so you get longer case life with out doing so your cases stretch and they crack just in front of the belt after 5 or 6 rounds. Also you center your case in the chamer better.

Back in the old days (early 20th century), the belt was seen as another form of rim. As the cases being used were long tapering cases (375-400 H & H, 375 H & H, 300 H & H) with not much shoulder to headspace on, the manufacturers felt that the belt system was required to properly headspace the cartridge. Also, it was theorised that even if the chamber was a little sloppy, the cartridge would headspace on the belt, so no real problem. Not a lot of handloaders at the time, so it worked pretty good (also, pressures just weren't that high). As the first magnums were all belted, it became a visual symbol of magnum power, and anything you wanted to sell as a "powerful magnum" needed a belt. There were other cases around that were just as powerful, or even moreso, some European cases, the 280 Ross, Newtons cartridges that had no belts, but the belted idea stayed with us, so we ended up with weird things like the 350 and 6.5 Remington Magnums etc. - Dan

The belt was originally placed on two cartridges: the .300 Howitzer & Howitzer and the .375 H & H. It served two purposes 1) so that a slope-shouldered case would reliably headspace (on the definite belt line) and 2) so that a rimless cartridge would extract in a double rifle reliably.

The belt has since been promoted and elevated to a status only otherwise attained by god himself. Its purpose now is to entice shooters to buy another rifle, with a power factor they do not need, to lie about recoil sensitivity, and to brag about ruined meat.

In fact, most new belted magnums have a sharp enough shoulder to easily headspace on and we are using them in bolt action rifles with really great extractors. The fact is that having a really good shoulder and a belt gives us a two-dimension headspace situation--the belt dimension and the shoulder-to dimension. That is not impossible to manage, but you can see that the great variations in chambers and reloading dies eventually produces combinations that are difficult to deal with. That is, the dimensional mismatch produces a chamber with a too long of a shoulder-to dimension. That makes a standard reloading die shorten the shoulder too much relative to that chamber and you start getting case separations from overworking the brass. Not dangerous, but a pain in the arse.

You can remedy a long chamber+short die situation by backing off the sizing die and only setting back the shoulder just enuff to allow the case to chamber easily. It will work that way. All manufcturers of belted case sizing dies make the dies so that they do not touch the belt anyway. Yes, you can get one made to size the belt, but you must special order it and pay a lot.

Hope that helps.

ok all this makes alot of sense, then why did't they just make these magnum cases with slopeing shoulders into rimmed cases like the 30-30 is. seems like this would have been a much simpler way of dealing with the headspace issues, also this would seem to work in sloppy chamber situations as well. and rimmed cases would be a natural for double rifles.

>then why did't they just make these magnum cases with slopeing shoulders into rimmed cases like the 30-30 <

Well, in fact there is a rimmed equivalent for each of the aforementioned cartridge. Why they needed both is a mystery to me, except that the belt will function in either the double rifle or something like the old Brevex magnum bolt actions and most new bolt actions, too. The rimmed versions were dubbed "flanged." Not seen much these days.

How is SLC these days and is weatherman Welty still around? He is the one that on one particularly cold winter forcast, told us that if we owned a brass monkey and had it in our yard, we should take it inside that night.

I always thought it was for added strength in that area. I'm such a dumbass!

Can't knock the belt to much folks, as it has been a boon
to us big bore nutz.It has had its place where it
was needed,458 Win, 458 Lott, 470 Capstick,all use the belt for headspace.And a whole bunch of older ones that
wildcatters did.And now we have coming 550 MAG, 600 OK,
my wildcats, and who knows.Ed.

>I always thought it was for added strength in that area. I'm such a dumbass!<

NO, YOU ARE NOT. You are simply a victim of advertising myths and gun writer hype. It is a marketing and sales thing.

The limit of the method for brass cartridge cases has been reached. It is the strength of the brass and a little more or less (as in a belt) does not change much of anything. Yes there are some very thin case designs that are weak, as in the old baloon-head cases, but beyond that not much makes any difference. Once the brass flows and gives up all that hot gas into the action, the action will go, too. That is why we should not push the envelope too much.

One advantage the belt does provide is when you are using very reduced loads or squib loads, which I have done a lot over the years in calibres like the 375 H&H.

With very reduced loads the headspace increases each shot with a rimless case, not so a belted or rimmed case.

Belted cases also look better, in my opinion.

Mike

>With very reduced loads the headspace increases each shot with a rimless case, not so a belted or rimmed case<

Excellent. hadn't thought of that.

Geo

The gunsmith Jack Belk did not believe me on this but he did try his 35 Whelen with primers only and soon found out if he reloaded the case enough times he would finish with a 358 Win with a very long neck

Mike

The rimmed cartridges were deemed unreliable for magazine feeding as well.
I read quite an interesting article recently on the belted magnum development and the long tapered shoulder was one of the reasons as was the rim.
If I can find the article I will post the pertinent parts.

'J

makes it nice to fireform though
woofer