7mm BELLM Load Data
Developed by Don Shearer, Littleton, CO.
Designed especially for TC Contenders Data developed in a TC Contender S-14 6 groove, 1-9" twist rate factory barrel, rechambered by Mike Bellm. Maximum Chamber Dimensions Cases: Reformed R-P .444 Marlin
Max. Trim Length: 2.200" Bullets: Hornady Primers: CC!-200, CCI-250, Fed. 210 Comments on the Cartridge.: First, the disclaimer stated on the .308 Bellm page applies. If you have not read it, please do so now.
Neither Don Shearer nor I assume any responsibility for loss, damage, injury or death resulting from the use of this data. It was thoroughly tested and proven safe in the barrel in which it was developed.
This particular barrel was an older 6-groove barrel originally chambered in 7mm TCU. The more recent 8-groove barrels may give slightly different results from those Don obtained. I am prejudiced toward .308 Bellm, but the 7mm Bellm is an outstanding cartridge also. If you are starting from an existing 7mm TCU barrel, my recommendation is to rechamber it to 7mm Bellm. There is just no comparison. Most of the older 7mm TCU factory barrels were chambered by TC on a drill press with the reamer held rigid in a drill chuck.
Because of this, most of the 7mm TCU chambers are offset from the bore, sometimes by a substantial amount. Thus when rechambering to 7mm Bellm using my procedure and throat dimensions, you should have little difficulty in finding loads that shoot much more accurately than were possible as a TCU, simply because I keep the throat diameter to a minimum and align the throat with the bore.
If you are starting from an existing 7-30 Waters barrel, I view the 7mm Bellm largely as a means to cut out the factory 7-30 Waters throat and improve accuracy. In other words, if the 7-30 Waters barrel you have shoots well as it is, you may want to question whether the slight gain in velocity warrants rechambering the barrel. It will shoot faster as a 7mm Bellm, but the 7-30 Waters is an outstanding Contender cartridge in its own right.
If it "ain't broke, don't fix it" may apply here. 7mm Bellm with its larger capacity and propensity for shooting best with slow powders also gives it an advantage with heavier bullets over the 7-30 Waters, and this may be important to you if you need the added penetration from 140 gr. and heavier bullets.
However, by and large for deer and antelope type game, I feel you are best off to stay with lighter, but well constructed bullets. You will get a flatter trajectory from the higher velocity at normal game ranges, and you will also get more reliable expansion.
Many folks jump to the heavier bullets, but I feel this is a mistake much of the time. So give more thought to the 120 to 130 gr. bullets, especially those tailored to handgun use. While .308 Bellm is quite manageable without a brake, 7mm Bellm with lighter bullets is even more "user friendly." If you do not want the noise of a brake under field conditions, I would recommend the 7mm Bellm over the .308 Bellm if you are somewhat recoil sensitive. 120 gr. bullets will do an excellent job on all but the biggest game with decent shot placement, and this is the beauty of an accurate barrel you can shoot well. You are more likely to put the bullet where it will do the job.
If it does not beat you up, you will also use it more and become even more proficient with it. To me there is nothing better than using a hunting gun as a varmint gun. The practice is invaluable.
The lighter 7mm bullets make 7mm Bellm better adapted for dual use as a varmint/big game cartridge, more so than with the .308 Bellm. The only down side to 7mm Bellm I can think of is it requires at least one forming step in addition to that with the 7mm-08 Rem. size die. At a minimum, you do have to run .444 Marlin cases through a .308 Win size die first; whereas, with the .308 Bellm only the .308 Win die is needed to both form and load cases.
I am more of a .30 cal. fan myself, but if you prefer 7mms, you will love the 7mm Bellm. 7mm Bellm Load Data
7mm Bellm Load Data
7mm (.284" dia.)
Hornady 120 gr. Flat Base Spire Point. # 2810
Refer to Hornady ballistics tables for energy and trajectory figures.
Use magnum primers with ball powders and the slow stick powders.
Bold figures are some of the highest velocities. Hornady 139 gr. Flat Base Spire Point #2820
Hornady 154 gr. Flat Base Spire Point #2830
Nosler 150 gr. Ballistic Tip #29600Powder:Wt. (gr):Muzzle Velocity (fps):Loading Denstity (%)Rel. 2245.02140 n/a
The above is a maximum load. Reduce charge 10% and work up.