5.6x50 R BELLM
5.6x50 R Bellm
.22-250 ballistics from a Contender or G2!
Accuracy typical of my chamber and throating: 5 shots at 125 yards, 33 gr. N-550, 50 gr. V-Max, moly coated. Rechambered TC 23" TC Custom Shop barrel, originally a .223 Imp. Target submitted by J.W.
5.6x50 R Bellm is based on the rimmed European 5.6x50 R case, which is dimensionally a .222 Rem. Mag with a 3mm longer body and a rim on it. The two rounds are so similar a standard 5.6x50 R chamber can be cut with a standard .222 Rem. Mag reamer simply run into the barrel deeper.
The Bellm version of it has the shoulder blown out to about a .371" shoulder diameter and 40 degree shoulder angle. The shoulder is also blown forward leaving a very short neck, thus creating all the powder capacity possible in this smaller diameter chamber that allows 55,000 psi plus pressures in the Contender or G2.
.223 Rem. barrels can be rechambered for it, but since the two chambers have the same body diameter, it is not possible to true up the runout inherent in most factory chambers.
On the other hand, since .22 Hornet chambers are smaller in diameter, they allow boring out the factory chamber runout and result more consistently in a much better chamber than when rechambering from .223 Rem., or the less common .222 Rem. of course.
Cases are made by first fire forming standard 5.6x50 R ammo in the "maximized" Bellm chamber. Cases headspace on the rim so no further provision for headspacing for fireforming purposes is required. Use a readily available .223 Rem. Ackley Imp. 40 degree shoulder Full Length size die backed off to locate the case shoulder for proper headspacing on the shoulder.
Since the .223 Rem. Imp. dies are for a shorter case body, the size die will not reach the web of the case, so as a separate operation, as required, run the cases through a Lee carbide .357 Magnum size die with the top of the die bored out for clearance of the longer case body inside the die. Cases fired at moderate pressure may not need to have the case web area sized and can be left as fireformed for a closer fit at the web. Once pressures expand the web to the point that this part of the case will not readily re-enter the chamber with only the upper part of the case sized, resizing the web area with the .357 Mag. size die is necessary. Lee .357 Mag. carbide dies I've checked have sized cases small enough while other brands have not.
Cases need to be sized to about .376" at the web, and many various brands and types of .357 Mag size dies do not size this small. Seat bullets with the .223 Rem. Imp. 40 degree shoulder seat die backed out just off of the case shoulder. The following data was developed by Blaine Eddy, Clearfield, UT back in the early 1990's.
The cartridge was promoted so long as brass was available, but when it became quite hard to obtain, the cartridge and this data for it were filed away. 5.6x50 R ammo and brass have become more popular in recent years, and you will find loaded ammo by Sellier & Bellot and Hirtenberger brass being offered by a number of companies. Of these two, Hirtenberger appears to be the better quality; however, RWS brass remains the best choice. It is pricey at a dollar or more per empty unprimed case, but again, this IS "top drawer" quality brass that lets the Contender do what no other case can.
Data for bullets up through 63 gr. are shown especially for those who might hunt deer with this cartridge. There are differing schools of thought regarding .22 caliber for big game, but one school insists .22 caliber is all you need, and from what I have seen, I tend to agree. The data was developed in a 20" custom barrel I made.
Twist was 1-14." Brass used at the time was RWS. Results should be similar with Hirtenberger or Sellier Bellot brass, but as with all loading data, always start low and work up. When comparing the following 5.6x50 R Bellm data to published .22-250 data, remember that most .22-250 data is taken from 24-26" barrels and will be about 100 to 150 fps. faster.
A rechambered 21" TC factory barrel will be about 30 fps faster than our 20" barrel data. Comparisons were made with various primers. With standard primers, loads were about 12-25 fps faster than with the Federal 205s that Blaine used. Data is also presented at the end using ball powders and CCI 450 Magnum primers which gave velocities about 25-50 fps faster than shown in the first section of the data using Federal 205 primers. Best powder overall in Blaines tests was IMR 4064 with IMR 4895 a close second.
AA2520 was not available when these tests were done, but based on more recent experience with this powder in .222 Mag.Imp barrels, it should be outstanding in the 5.6x50 R Bellm as well. Accuracy was excellent with many 100 yard groups going into 1/2" or less. Best powders for accuracy were IMR 4064, IMR 4895, WW748, and H380. .22-250 velocities and superb accuracy from a little 6 pound rifle make the 5.6x50 R Bellm a very respectable varmint rig, and with 60 to 70 gr. bullets from 1-12" twist TC factory barrels it would do well on deer sized game also. Note: This case holds nearly 37 gr. of ball powder, and about 34 gr. of stick powder, compressed.
Max. loads must be worked up for each individual barrel and can be taken to the limits of the brass without damage to the barrel or frame due to the small diameter of the 5.6x50 R case. Loads that lightly crater the primer and show no imprint of the rimfire firing pin hole on the case head should be considered maximum, taking into consideration also pressure increases with increases in temperature.
All loads should be reduced at least 10% below the maximum loads shown and worked up carefully, especially where only the max loads are listed.
Due to variations in individual barrels and procedures used by individual reloaders, neither Blaine Eddy nor I assume any liability for the results obtained from the use of this data. Top loads shown are absolute maximum for the barrel in which they were tested, but were safe.
AA2520 powder has proven to be superb in the .222 Rem Mag Imp. and should be an excellent powder in the 5.6x50 R Bellm as well. However, I have not tried it yet. AA2700 is too slow for the .222 Mag Imp, but might be useful in the 5.6.