View Full Version : Belted case headspaceing problem?

March 21, 2008, 03:53 PM
I have been wondering this for years and get different answers all the time. If a belted bottle neck case headspaces on the belt, and alot of "experts" say this is inferior to headspaceing on the shoulder, then why couldn't you just partialy size a belted case and make it headspace on the shoulder. I realize this would only work in the chamber that the case was fired in to begin with, but if I only own 1 .300 mag. is there any reason why this wouldn't work? I know we have neck sized only for the same reason for years, to match the chamber as closely as posible on rimless bottle neck cases with zero headspace. Common sense tells me that if a chamber was a little long compared to where your sizeing die sets the shoulder, then done the way I described the case will now headspace on the shoulder and the belt would still keep the rear of the case centered in the chamber at the rear. I've never owned a belted magnum, just something I thought of when I read the coments like the ones you read in Cartrages Of The World and others.

Jim Watson
March 21, 2008, 04:41 PM
I have seen this recommended many times. I figured it would be common practice by shooters who wanted to get longer case life than setting the sizing die down on the shellholder but easier chambering than neck sizing. But then I don't have a belted magnum to try it on.

10 Spot Terminator
March 21, 2008, 11:16 PM
The reason I began reloading was when the ammo for my .264 Win.Mag. disappeared suddenly from winchester some 8 years ago for a short time and put me in a panic. Reading all of the literature I could find before diving in head first on this venture I too studied this dilemma and started out with a set of RCBS dies and found them not to be setting the shoulders back at all when sizing as close to the belt as possible . I soon found that RCBS will custom tweak your dies for you at no cost other than you pay to ship them one way only . You send them your dies and 5 unsized fire formed pieces of brass from your rifle and tell them you want to get a .0001 or .0002 or ??? setback on the shoulder when full length sized and let them do their stuff, they nailed the .0001 for me I asked for . I have 6 loadings currently on my brass with very little trimming and have annealed the necks 2 times just because there is so little neck on them and dont want to split any . Food for thought . Just now working on a 300 Win. Mag. Will be putting out some posts on this soon I am sure .

James K
March 27, 2008, 12:43 PM
The best reason for doing just that is that the belt-case body angle is a weak point in belted cases. When there is enough headspace to allow the case to set back, the case stretches. Some stretching is normal and necessary to allow the chamber to accept all ammunition that is within specs. The same thing happens with all cases, but only the belted case has a weak angle point in the thinner area of the case. The result is that belted cases don't last long in reloading and neck sizing is the best way to get any reasonable case life. Of course, the cases must then always be used in the same rifle.


Harry Bonar
March 27, 2008, 07:32 PM
I always size my "belted" cases this way (on the sholder) - not only do you get good case life but an increase in accuracy too. I size my cases so there is a slight feel in closing the bolt.
Harry B.

T. O'Heir
March 28, 2008, 09:57 PM
Cartridges do not have headspace. Headspace is a manufacturing tolerance only. Nothing you do to a case will do anything to the headspace.

Harry Bonar
March 29, 2008, 07:26 PM
It is true that the rifle is set up with the correct headspace; between a saami guage from the "go" tolerance to the 'no-go' and 'field' guages - and if it closes on a 'go' guage and will not close on a 'no-go" guage the rifle is 'within tolerance" and is fit to be sold and used with factory ammunition (this does not apply to wildcats.)
But this is just a very superficial discussion of headspace. the tolerance between 'go" and 'no-go' is usually around .006! Now, if you're handloading and you size your cases with a die that restores the case to minimum dimension and your rifle just barely will not close on a "no-go" guage you will end up with a situation where you have 'excess' headspace! I had a Sako 22-250 that was well within tolerance (would not close on a "no-go" guage) and yet my factory cases had primers that had backed out and smeared slightly over the head of the case! while this was a "safe" rifle and within specification to my mind it had "excessive headspace. One need only to look at the saami case and chamber dimensions to see that, with a belted magnum case (the worst and most dangerous case design) with a maximum chamber and a minimum case you can end up with close to .015 or more in the distance from bolt face to the case when case is in contact with the belt recess in the chamber - check it out! The same can apply to rimless cases.
Headspace can be within spec in your rifle but an accumulation of errors, especially in handloading can result in an excess amount to headspace even though your rifle is "in spec."
For instance; the belted cae dimension from head to belt should be .220. I've measured belted cases that were only .216. I have read somewhere that originally Britiush tolerances for their belted magnum cases in headspace guages was .220 "go" and .222 "no-go." Now sammi has a totally different set of spec, look it up!
i agree headspace is in the rifle, already set by factory specs but that doesn"t mean you can"t have excess headspace in a factory rifle!
Harry B.

James K
March 30, 2008, 09:43 PM
Some people distinguish between rifle headspace and cartridge headspace. The former is part of the rifle and is OK if the rifle measures correctly by the gauges. The latter is a factor of cartridge dimensions and they can be wrong, even out of spec, in factory ammo. Further, cases have tolerances too, so there are "long" and "short" cases. A NO-GO gauge test ensures that even the shortest case that is within specs will not stretch enough to break in the chamber. (The GO gauge ensures that the longest case that is within specs will chamber.)

But those checks depend a lot on the case material and other factors, including weak spots in the case itself, and that is where the sharp right angle of the belted case presents a problem.

The fact is that the belted case is an old Holland and Holland design, intended to add strength to a case. Fine, but those English sporting cartridges were never intended for reloading, something the English generally do not do. Only the wealthy owned such rifles and they fired them very little except at animals, usually in Africa or India, and at short ranges. I am told that even professional hunters today do not do a lot of practice shooting, though they are good enough to achieve "minute of elephant", and they use only factory cartridges, not reloads.


Harry Bonar
March 31, 2008, 06:42 PM
For instance: As Doc and I guarded against in chambering a 458 Winchester to 458 Lott, when lengthening the chamber, when you come close to finishing you must be sure not to contact the "belt recess". Some experts have re-chambering reamers for the belted case ground with no cutting teeth on the belt cutting area. good idea! This way you do not deepen the belt - and if you do you have an unsupported area in front of the belt. Firing a cartridge in such a mis-cut chamber gives "spectacular results" as the thin area in the case lets loose!
May I sound a note of caution here - If you do headspace on the sholder with a belted mag. you are opening a small area of the same nature as the 458 Lott with a mis-cut rechambering job. Correcting the problem of the belted case by headspacing on the sholder does expose a very slight gap at the forward portion of the case - it"s dangerous! But with saami tolerances in effect it does not seem to have a problem, but I don't like it.
The belted case is by far the most dangerous case design extant ( and there is no need for a belt on a "bottleneck case). if manufacturers would make their cases actually .220 to the belt and chambers at .220 deep it wouldn't be so bad - I don't think U.s. companies really understand belted cases. The "belt" to begin with was for straight walled cases.
Harry B.

April 10, 2008, 11:57 PM
The fact is that the belted case is an old Holland and Holland design, intended to add strength to a case. Fine, but those English sporting cartridges were never intended for reloading, something the English generally do not do.

I've oftened wondered about this. I have a 300 Win Mag and just starting to get into reloading - mostly reading posts on this site getting some great advice and knowledge.

Are belted magnums a poor choice for reloading. Is the, say 300 WSM, easier to reload?

May 16, 2008, 03:28 PM
Been reloading Rem. 7mm Mag and 375H&H mag for about 6mos.

They are a big pain compared to .270Win and .22-250 rifles I also load.

I neck-size them. I set the OAL way out on the 7mm Mag and do factory length with roll crimp for the 375H&H(at Dad's request).

I get a lot of stuck cases in the 7mm Mag. Some extra Lee lube takes care of that.

I often read that the belt is unnecessary and that headspacing off the shoulder rather than the belt is more accurate design.

The new non-belted magnums have more case capacity than the older belted magnums, resulting in higher velocities when properly loaded.

Harry Bonar
May 16, 2008, 03:59 PM
When I was chambering rifles of a belted maggie nature I made a .220 guage myself and set my heaspace to a maximum of .220 never over that.
For my son I actually headspaced one at .218 because only we would be using it = this let there be only about .002 between the bolt face and the head of the cartridge.
Yes, I know this is non standard, but you could have chambered any American belted maggie case just fine.
Harry B.