About the 5.6x50 R Bellm Cartridges
Cartridges in blue are linked to data pages under construction.
5.6x50 R Bellm
.257x50 R Bellm (no data)
7x50 R Bellm
of which are reloaded with common dies. Read on.
What is the 5.6x50 R?
It is a European cartridge that in standard form has the same body dimensions as a standard .222 Rem. Mag case.... same except for the case body length. In millimeters, the .222 Rem. Mag. case is 47mm long, and the 5.6 x50 R is of course 50mm long.... roughly .2" longer. The dimensions are so close that the .222 Rem. Mag. chamber reamer can simply be run in deeper to create a proper chamber for the standard 5.6x50 R. Likewise, it can be sized and reloaded using .222 Rem. Mag. dies backed off the appropriate amount. As with my maximized versions of the 5.6x50 R, case webs are sized with a Lee carbide .357 Mag. pistol size die as a separate operation, but I am getting ahead of myself. It shares the same basic .375" case head diameter of the .223 Rem, and thus all of the TCU rounds, which opens doors wide open where reloading dies are concerned.
A Little History:
The 5.6x50 R case was developed in Europe for shooting roe deer with approximately 70 gr. bullets. It is made in both rimmed and rimless versions, but for the Contender, the rimmed case has many virtues favoring it over the rimless version.
Back when I first started working with the 5.6x50 R case in the early '90s, only RWS brass was being imported, and from Huntington's it was about $1 per empty unprimed case. Later the price went up over $1. Supplies were spotty, and later still, it became unavailable. For what it did for the Contender, the cost of the brass while high was justified, especially in the .22, 6mm, and 6.5mm versions. Nothing else would provide the ballistics available from the 5.6x50 R case without risk of stretching frames.
But when it did become unavailable, I abandoned the cartridges. Then last year Huntington's offered it imported from Hirtenberger, a German ammunition manufacturer, at $39 per hundred, which while a bit high is not bad at all for premium quality imported brass.... and a long way from over $1 each for RWS brass. Sellier & Bellot is supposed to be bringing it in also, but I have yet to see any.
Concept behind the Bellm cases:
The Contender is quite sensitive to back thrust from higher pressure, large diameter cartridges, which is why, for example, the Contender cannot be chambered for 50,000 psi + rounds like .22-250 Rem. Yet, smaller diameter cases like .223 Rem which generate pressures often in excess of 55,000 psi present no undue stress on the Contender frame. It is pounds per square inch, and the smaller diameter chamber presents a smaller fraction of a square inch for the gas to push on. Thus the .375" diameter .223 Rem. case head pushes back on the frame with less force than the larger, greater fraction of a square inch, .465" diameter head of the .22-250.
For the mechanically inclined or those who remember a little from physics, I like to use hydraulics as an analogy. If you have a piece of earth moving machinery like a backhoe or bulldozer with a set hydraulic system with say about a 2,200 psi operating pressure, but you need to move a heavy load with that 2200 psi, what do you do? Use a larger diameter hydraulic cylinder. Take a look at machinery sometime and note that the hydraulic cylinders are not pencil size. Some are out and out large, yet, and mechanics correct me if I am wrong, but I believe most equipment operates at about the same pressure. With a given pressure, you get more "push" with a greater surface area on the face of the ram. Works the same way with cartridges, only you want LESS push out the back from the pressure generated, so you use a SMALLER DIAMETER ram.... ie., smaller diameter case head. More appropriately, it is the diameter of the chamber. And then some will argue that it really is the inside diameter of the case..... but this is splitting hairs beyond really useful application, unless you want to make an argument for thicker, stronger brass at the case web. Anyway, this is the principle behind using smaller diameter cases to permit higher operating pressures without putting too much pressure load on the Contender frame.
So why the 5.6x50 R case?
Like I said, it permits the same high operating pressures as the .223 Rem., but when this long case is blown out nearly straight leaving a very short neck it allows enough powder of the right burning rates to make the Contender sing. +/-, depending on the powder density and shape, the blown out case will hold up to about 32 gr. of stick powder and 36 gr. of ball powder. Significant.
Reloading Dies for the 5.6x50 R and cases based on it.
All sizing and loading for the standard 5.6x50 R and my blown-out versions based on it is accomplished with common dies.
Standard 5.6x50 R, which is also recommended as an accuracy "fix" to cut out factory .223 Rem throats when rechambered to this round, can be sized and reloaded with either standard .223 Rem. dies or standard .222 Rem. Mag. full length dies. Dimensions are dimensions.... regardless of what is stamped on the dies. Both of these dies are too short to reach the webs of the cases, so run them through a Lee .357 Mag. carbide pistol size die. Why Lee? Most .357 Mag size dies do not size small enough. Lee does. But if your .357 dies will size to .375" or smaller, they are fine.
5.6x50 R Bellm, again also an accuracy "fix" for factory .223 Rem. barrels, is sized and loaded with either .223 Rem Imp. 40 degree full length dies or less common .222 Rem. Mag. Imp 40 degree full length dies. Run the cases through a Lee .357 Mag carbide pistol size die to size the webs.
6x50 R Bellm. Use 6mm TCU full length dies and the Lee .357 Mag carbide pistol size die to size the case webs. Again, if your .357 Mag die sizes to .375" or smaller it is fine.
.257x50 R Bellm. Use .257 TCU full length dies from Redding, or RCBS if they have them in stock. plus the Lee .357 Mag carbide pistol size die to size the case webs, or your .357 Mag die if it sizes to .375" or smaller. This TCU round never really caught on, so dies will be more scarce for it.
6.5x50 R Bellm. Use 6.5 TCU full length dies and the Lee .357 Mag carbide pistol size die to size the case webs, or your .357 Mag die if it sizes to .375" or smaller. 6.5 TCU dies are still fairly common, plus you may find them used.
7x50 R Bellm. Use 7mm TCU full length dies and the Lee .357 Mag carbide pistol size die to size the case webs, or your .357 Mag die if it sizes to .375" or smaller.
See how simple that is?
The TCU dies typically size the case shoulders to about .368." My chamber shoulder is about .370." Note that in each instance I say to use "full length" dies. If you manage to keep loads mild and get by with neck sizing, great for you, but don't ever call me complaining about misfires and accuracy problems with neck sized cases or cases not properly full length resized and the shoulders bumped back where they belong. I'll simply head you to "The Experiment Every Contender Shooter Should Perform," tell you to take two aspirin, and call me in the morning.
Note Also... the 5.6x50R brass can be used to make rimmed versions of all the cases with a .375" head diameter.... some easier than others..... but it can be used to make rimmed .221 FB, .17 Mach IV, .17 Rem.,.222 Rem. .223 Rem and all the TCUs, the .222 Rem. Mag, and all the improved variations of these. If I am doing a rechamber for any of these rounds, and you think you might someday want to try rimmed brass, just let me know and I will cut the rim counter bore in the end of the barrel for the 5.6x50 R case rim. Its presence has no effect whatever on the use of rimless ammo, and by using the spring loaded rimless extractor, you can shoot rimmed and rimless ammo interchangeably. Or you can remove the spring and shoot only rimmed ammo. Set up time for rechambering is more than what it takes to bore the rim counterbore. If I do it in the process of rechambering, I do not charge extra for the counterbore, so just ask if you think you might want it. It is easiest and cheapest to do it on the head end while the barrel is in the lathe.
(As this section of the site is being prepared, I am about to start doing 5.6x50 R based chambers and owners of these barrels will be wanting data. Data will follow soon.)
Here is a link for a source of 5.6x50 R brass: http://www.buffaloarms.com/baco2.htm