Home Forums Hunting & Shooting Ask The Gunwriters belted vs. non belted mags

The problem with belted cases is more a function of the brass manufacturer than the case design. A belted magnum headspaces on the belt, IOW the forward movement when the case is hit by the firing pin is stopped when the front of the belt hits the cutout in the chamber. However, on new cases, case manufacturers typically put twice as much (or more) of a gap between the case shoulder and the chamber shoulder as they do unbelted cases. This shoulder clearance on a belted case is defined as "head clearance".

The additional head clearance on belted cases are what leads to a greater chance for thinning at the web and case head separations. For instance I took the following measurements with a Hornady Headspace Gauge which measures to the datum line



BELTED CASES
338 win mag Mato - new case 2.097", fully fire formed case 2.124" - head clearance .027"

300 win mag Mato - new case 2.253", fully fire formed case 2.2725" - head clearance .0195"

264 win mag pre-64 Winchester - new case 2.109", fully fire formed case 2.1385" - head clearance .0295"

6.5 rem mag custom rebarrel - new case 1.768", fully fire formed case 1.785" - head clearance .017"

The headspace as measured on the belt on the first 3 rifles was between .003" and .007" and on the custom rebarrel was 0.000" but the brass still has to expand to hit the shoulder and expand the head clearance amount before you can headspace on the shoulder.

UNBELTED CASE
338RUM custom rebarrel - new case 2.374", fully fire formed case 2.3785" - headspace .0045"

30-06 Steyr - new case 2.040", fully fire formed case 2.0515" - headspace .0115"

22-250 Remington - new case 1.577", fully fire formed case 1.5875" - headspace .0105"

So the case manufacturers put a lot more head clearance on the belted magnum cases to begin with and that causes most of the problems. Once you have fire formed the case and headspace on the shoulder all the problems go away. Problem is the initial expansion has already caused some problems with thinning at the pressure ring where the powder column ends and the case head begins


As you can see the belt has no effect on the powder capacity and removal of it would not increase or decrease the case capacity at all.

Your measurements are in line with what I have found. However, I have not had an issue with reduced brass life in a belted case vs a non-belted case. They all last me half a dozen firings before they lose neck tension and need annealing, belt or not. I don't usually take the time to anneal, so I typically replace all my cases every six firings.

I did try necking up and pushing back 300 Win mag brass for a 338 Win mag, but I kept getting "seams" in the shoulder. However, the idea was to soak up some of that .018 to .025" of shoudler growth. Turns out it wasn't worth the effort.

How did we get from the original question to "brass life", which wasn't mentioned by the OP?

For longer brass life for the 338 Win Mag I use 358 Norma Mag brass. The shoulder is .040" LONGER than 338 Win Mag. When you size and originally form the case you can do so setting the shoulder back only the usual .001" just enough to chamber. The brass then lasts as long as any unbelted brass as you have eliminated that initial stretch you get when you form domestic belted brass.

Incidentally, I've run into shoulders that have needed to stretch as much as .035" intially. Those are candidates for immediate head separation at first firing. Only way I've found to make those work is with a full case of an ultra slow canon powder and a bullet; the COW method of case forming without a bullet doesn't work as it still produces stretch just forward of the belt.

Some Norma Mag brass formed this way has gotten as many as 28 reloads for me. I anneal every 4 reloads. They tend to thin at the neck and reduce bullet "grip" because of this after a few trims but there is little evidence of stretch forward of the belt in sectioned cases.

The base to datum line measurement on an unfired unbelted case compared to fired measurement is important (probably only thing important) if thinning of the brass directly ahead of the case web is the concern. On a belted magnum, it's not so simple. The difference between fired and unfired is caused by the case head moving rearward towards the bolt face and this is dependant on how much clearance there was between said case head and bolt face when the belt stopped the case from moving forward when the firing pin struck it. The other half of the equation is the datum line to barrel shoulder clearance under the same circumstances. The first half is harmful the second half isn't, so how much of those large measurements are due to the first half of this equation is my question. Military testing has shown new properly made cases to not separate on the first firing til .060 to .070 headspace. If .035 difference is all due to the first half of the equation and the shell is resized back to factory specs, one would have to look out after 2-3 loadings. I suspect the second half is a good part of this equation.
dan

I think your question, IMHO anyway, summed up what is often the fisherman's plight, which is, was this manufactored to catch the fish or the fisherman?

I'm not saying there are not theoretical arguments for the beltless cartridges but I've not seen them play out in many years of shooting and hunting with both types. A different kettle of fish certainly (pun intended), but the beltless cases are often very straight and/or short which can often be a very real disadvantage by themselves.

In fact, I've almost come to think of the 375 H&H as the "perfect" cartridge and though I've never had or shot one, the 300 H&H it's sidekick perfecto. Both cartridges cases are a pole apart from today's beltless, straight, wide, short cases.

Well, if the .300 WM was invented today, it probably wouldn't have a belt. What does this mean? A cheaper-to-make round.

I suppose there are theoretical arguments against the belted round, but these theories frequently ignore facts. And the fact is the .300 WM is an excellent round, as are other belted rounds no doubt (can't say as I've never owned any others.)

They are what they are.

Can you explain more fully.

What "difference between fired and unfired" are you referring to? Do you mean the HEADSPACE of the belted case?

Didn't mean to hi-jack the thread, Bobski. My answer to the OP's question would be that extreme accuracy can be had with or without a belt. However if they made a caliber with the same case capacity and configuration of the 300 win mag without a belt, put me in line to buy one. The belt is unnecessary, takes up mag room and encourages the brass manufactures to manufacture brass with too much head clearance. That being said, I would rather have the 300 win mag with a belt than not have one at all and the belt does not create any problem itself.

If anyone has Handloader #140 available, Gil Sengel (a writer who never seems to get the credit that he should)has an article entitled "A Handloader Looks at The Belted Magnum Case" in that issue. He points out that the time-honored practice of headspacing the cases on the shoulder creates a problem when case dimensions are near minimum and chamber dimensions are near maximum and hot loads are fired. (Which is probably going to be the case - after all, this is a magnum and folks are looking for magnum performance, right?) Those who understand all of this much better than I do would get a great deal more from reading the article than I can summarize. In his closing paragraph, he does say, "All this indicates that the belted case can be more of a liability than an asset to handloaders. Put another way, the 7mm Remington and .300 Winchester magnums need belted cases just as badly as a bullfrog needs a spare tire and running lights!"

But the .700 Rem Mag and the .300 WM HAVE belted cases.

So while his point may be interesting, it is also irrelvant.

Several years ago, when the short fats (.300 WSM) and long fat (.300 RUM) were developed, there was so much publicity that I thought belted cartridges and rimless cartridges like the .30-06 would soon be things of the past.

My favorite cartridges have long been the various Weatherby cartridges, although I did sell my .300 Wth. and buy a .300 RUM.

I wrote to Weatherby, advising them that belted brass would soon be obsolete, and suggesting they design a line of Beltless Weatherby Magnums. I suggested the .300 RUM case as a starting point, with a case the same length of the 7 MM, .270, and .257 Weatherbys. For the larger calibers, .30 and up, I suggested a case similiar to the full length .300 RUM.

The difference I suggested was that the shoulder be distinctive radious shape on Weatherby cartridges, instead of the present shape.

Surprise, Surprise, one day I received a telephone call from a Weatherby vice president, thanking me for the suggtestion.

We talked a few minutes, then he said that the radioused shoulder on Weatherby cartridges would not work if the case was rimless. He went on to explain that a rimless case of this design would not headspace on the radioused shoulder.

But, he did thank me for thinking of Weatherby, and said that they would welcome any suggestions I came up with.

While I had him on the phone, I suggested that the .460 Weatherby was too heavy and had too much recoil for most people (including me). I suggested a smaller case, with the capability of moving a 500 grain bullet about 2300 to 2400 FPS.

This would be for people who hunt DG, but do not want the recoil and weight of the .460. It could be built on the same action as the .300 and .340, at a considerable saving of weight.

He said they had been thinking along those lines, also. Imigine my surprise when the Mark V was introduced in .458 Lott.

The Lott case is not the design I suggested, but it works just as well, maybe better. I suggested the .300, 340, and .375 case size and shape be necked up to .458.

But, getting back to the original post, apparantly the radioused shoulder will not work on a beltless case, so if you want a Weatherby cartridge, you will have to put up with the belt.

I have, since 1963, when I got my first Weatherby, and it doesn't keep me awake at night fretting about it. I would rather have a belted Weatherby than no Weatherby at all.

Anybody that sees any inherent disadvantages to belted case versus a non-belted is as clueless as the day is long. A totally transparent non-issue. jorge

thanks for the reply's, some good points made.

1234, i too am a wby fan, and think they should re-do the line up, what i had in mind is a little different than you tho, i'd think the 300wby, taken all the way down to 257, keep the venturi shoulder, thats what make them Weatherby's.

Rosco1:

A .257 on the .300 WBY case would be a screamer, that's for sure.

Someone makes one similiar, except they used the 8 MM Rem. Mag. Case, and from what I've read, they claim fantastic things for it.

Years ago, a 7mm on the .300 case was moderately popular. A woman, I think her name was Devito, set a world record at the original 1000 yard bench rest matches with one.

Imigine a .257, a .270, and a 7 mm on the .300 case. Enough to make your eyes roll back into your head and your mouth water, but my dream cartridge would be a 7mm on the .300 RUM case shortened 1/2 inch, or the .300 WSM case lengthened 1/2 inch.

I can't understand why Winchester did't design the cases like that to begin with.

ya the line up would be like the 257,270 and 7mm stw's, but with wby flavor. i know the 7x300 wby is a popular wildcat already.

I think Roy would want it that way! but i'm sure the cost of the new ones, and keeping ammo available for the old ones will keep it from becoming a reality.

1234567 - thanks for the interesting information from Weatherby. Does that mean that following the time-honored practice of sizing belted cartidges so they headspace on the shoulder does not work with the Weatherby cartidges or does it mean that to do so alters the shoulder in some way that makes it no longer a Weatherby cartridge? I can be rather slow on the up-take, so if I am missing something here I apologize. Thanks for your patience. Best, John

Since the question is in regards to pure accuracy, rather than function or brass life, I guess we should ask how may bench rest shooters use belted cases and how many use beltless ones?

Ken Brucklacher Sets 1000-Yard Score Record: 100-8X
Filed under: Gunsmithing, News � Tags: 1000 Yard, Norma, Record, Score, Sierra � Editor @ 11 am

Ken Brucklacher, current President of the Original Pensylvania 1000-yard Benchrest Club (Williamsport), joined the immortals this Sunday, May 3rd. Shooting a .300 Weatherby Mag with 240gr Sierra MatchKings, Ken set a new 10-shot Heavy Gun World Record score of 100-8X. The group size was pretty amazing too. A measured 3.137″, Ken�s ten shots also set a new group record at the Williamsport range, besting the previous mark set 13 years ago by John Voneida (3.151″ and 100 score). Brucklacher�s group is just 0.089″ larger than the 3.048″ all-time, 1000-yard small group shot last month by Joel Pendergraft.

Conditions were good when Ken set the record. It was cool, with overcast skies, and the winds were calm with �the flags still hanging down�. Ken said he �took his time, made sure he was on for every shot.� He pretty much held �on the center of the white patch� in the 1000-yard target. The result was spectacular, as you can see below

I seriously doubt that anyone has any sound data to make such a statement that one is more accurate!

I will say that given the choice between a belted case and a non belted case of the same performance level I'd prefer the nonbelted case for reloading purposes as I can control the non belted case better.....is this a big deal?......nope not at all.....

However if Ruger necked down the .375 Ruger to .30 caliber and shortened the case about 1/8" I'd be ordering a chambering reamer the next day.

5sDad:

The original discussion was about the Weatherby shoulder and a beltless case. The person I talked to said a rimless, beltless case would not headspace on the radioused shoulder. It might have been that the blow from the firing pin would drive the case shoulder into the chamber shoulder, deforming it.

The radioused shoulder doesn't appear to have a datum line, so my guess is that it wouldn't headspace would not be uniform without the belt.

I don't think the shoulder would be altered, but I'm guessing that the practice of sizing belted cartridges to headspace on the shoulder would not work on Weatherby shoulders.

It has been a few years since I reloaded for my Weatherby's, but IIRC, the neck radious of my FL sizing die seems to be slightly different from the radious of the chamber, so FL sizing does alter the neck shape slightly, but not enough so that it would no longer be a Weatherby cartridge.

However, I don't see that it would make any difference if you used a neck sizing die with a large enough body so that neither the neck shape or body taper were changed, such as one of the button dies, and only sized to the depth the bullet seats.

Of course, it goes without saying that you would have to restrict the cases to one particular rifle, but I have always done that anyway.

I haven't reloaded since I came on this forum, and I didn't even know about headspacing a belted cartridge on the shoulder before I read about it here. I do remember that all the Weatherby cartridges I have reloaded would not chamber easily when partial sized in the FL die, but that could have been because of a little difference between the chamber and die shape.

The theory behind belted cases not being as accurate a rimless cases is based on the fact that a FL sized case, or a new case is a few thousands smaller than the chamber, causing the cartridge to lie on the bottom of the chamber and the bullet not lining up perfectly with the bore.

That may or may not be true. I don't know, but when people set 1000 yard records and win 1000 yard matches at Camp Perry with belted cases, then it would seem that that theory flies out the window.

Besides, neck sizing with a button die, as mentioned above, would eliminate the cartridge laying on the bottom of the chamber and not being centered.

Many years ago, I was fortunate enough to shoot at matches where shooters from the Army Markmanship Unit were present. I talked to them a good bit, and they were always willing to give advice to a poor civilian. I can remember them talking about the 1000 yard cartridges used in the Wimbleton and Leech cup matches, which were the .30-338, and they mentioned that some rifles were chambered for this cartridge, but the belt was turned off. The chamber was not cut for the belt, either.

I never saw one altered this way, but I don't doubt they did it if they said they did. This cartridge would have been something like the .30 Newton.

One of my fondest memories of those times was being teamed with a person who had won the Wimbleton twice and the Leech once, once the Wimbleton and Leech in the same year, the only person up until that time to do it.

Thanks for the reply and information - very interesting. Best, John