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 (.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 120 gr. Flat Base Spire Point.  # 2810

Powder:

Wt. (gr):

Muzzle Velocity (fps):

Loading Denstity (%)

IMR 4895

39..0

2324

80

 

41.0

2461

85

 

43.0

2547

89

Win 760

42.0 2175 86
  44.0 2341 90
  46.0 2446 94
 IMR 4350 43.0 2215 87
  45.0 2316 91
  47.0 2439 95
IMR 4320 38.0 2199 78
  40.0 2351 82
  41.0 2379 84
IMR 4064 38.0 2183 86
  40.0 2321 91
  42.0 2472 95
AA 2700 41.0 2208 85
  43.0 2300 90
  45.0 2495 94
IMR 4831 45.0 2129 92
  47.0 2271 96
  49.0 2409 100
Reloader 22 44.0 2035 86
  46.0 2126 90
  49.0 2208 96

 

Hornady 139 gr. Flat Base Spire Point #2820

Powder: Wt. (gr): Muzzle Velocity (fps): Loading Denstity (%)
IMR 4895 37.0 2185 76
  39.0 2312 80
  40.0 2374 82
Win 760 40.0 2040 82
  42.0 2178 86
  44.0 2280 90
IMR 4350 41.0 2052 96
  44.0 2219 98
  45.0 2292 100
IMR 4064 36.0 2123 82
  38.0 2240 86
  40.0 2344 90
AA 2700 39.0 2137 80
  41.0 2235 84
  43.0 2348 88
IMR 4831 44.0 2089 91
  45.0 2131 93
  47.0 2274 97
Reloader 22 44.0 2024 89
  46.0 2166 93
  48.0 2242 97

 

Hornady 154 gr. Flat Base Spire Point #2830

Powder: Wt. (gr): Muzzle Velocity (fps): Loading Denstity (%)
IMR 4895 34.0 2008 70
  36.0 2134 74
  38.0 2223 78
Win 760 38.0 1959 78
  40.0 2052 82
  42.0 2143 86
IMR 4350 40.0 2008 85
  42.0 2101 89
  44.0 2242 94
IMR 4064 34.0 1975 77
  36.0 2073 86
  38.0 2188 na
IMR 4831 43.0 2057 91
  44.0 2121 96
  45.5 2223 100
Reloader 22 43.0 2018 89
  45.0 2113 93
  46.5 2204 96

Nosler 150 gr. Ballistic Tip #29600

Powder: Wt. (gr): Muzzle Velocity (fps): Loading Denstity (%)
Rel. 22 45.0 2140  n/a

The above is a maximum load.  Reduce charge 10% and work up.

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