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7mm WSM / History:
Centerfire Rifle Cartridges
Written by: Kim Lockhart, Copyright.

7mm WSM:
 The 7mm WSM is a new twenty-eight caliber centerfire rifle cartridge developed in partnership with Browning Arms Company and Winchester ammunition, making its debut and introduced to the shooting public in 2001. The new 7mm short magnum cartridge is chambered in Winchester's Model 70 bolt action rifle.

 The 7mm WSM is a commercial cartridge based on the 404 jeffery cartridge case, shortening to 2.100" and necking down to .284" caliber and sharpening the shoulder angle to 35 degrees. The new 7mm WSM cartridge offers plenty of case capacity for tailored handloads. The 7mm WSM cartridge achieves its useful purpose as an excellent long range cartridge for, mule deer, sheep, black bear and elk, .284" caliber is a time proven caliber for elk and deer size game animals.

 The 7mm WSM cartridge is a well thought out cartridge as Winchester is no stranger in .284" caliber cartridge development. Winchester has now developed 2 cartridges in this caliber; (284 Winchester in 1963), and (7mm WSM in 2001).

 The 7mm WSM factory loadings show a velocity of 3,225 feet per second for a 140 grain bullet for deer and sheep hunting and this translates to moderate recoil for the shooter with plenty of bullet energy at the 500 yard mark to flatten a larger deer size animal.

 The 7mm WSM cartridge, chambered in a short actioned light-weight rifle may well be the ultimate combination for a superb mountain rifle, that offers a slight increase in bullet frontal mass and energy than that offered by the 270 WSM in rugged terrain and most rifles chambered in this cartridge show plenty of accuracy with long range 160 grain weight bullets.

7mm WSM Cartridge Dimensions:
Bullet Diameter = .284".
Neck Diameter = .321".
Shoulder Diameter = .538".
Shoulder Angle = 35 Degrees.
Base Diameter = .555".
Rim Diameter = .535".
Case Body Length = 1.857".
Case Shoulder Length = .155".
Case Neck Length = .243".
Case Overall Length = 2.100".
Cartridge Overall Length = 2.860".

7mm WSM Rifle Barrel Specifications:
Bore Groove Diameter = .284".
Barrel Length = 24".
Barrel Twist Rate = 1 in 9 1/2".

7mm WSM Rifle Accuracy:
Properly mount your rifle scope.
Properly break-in your rifle barrel.
Properly sight-in your rifle using a accurate sight-in target.

Ballistics

Winchester, 7mm WSM Ammunition Short Range Ballistics Chart:
Winchester
Bullet
Type:
Bullet
Weight
Grains
Bullet
Ballistic
Coefficient
Muzzle
Velocity
Fps.
Muzzle
Energy
Ft. Lbs.
Rifle
Zero
100 Yds.
Bullet
Drop
200 Yds.
Bullet
Drop
250 Yds.
Accubond CT 140 .460 3,225 3,233 0 - 2.3" - 5.2"
Ballistic Silvertip 140 .460 3,225 3,233 0 - 2.3" - 5.2"
Power Core 140 .416 3,225 2,233 0 - 2.4" - 5.3"
Power Max 150 .393 3,200 3,410 0 - 2.5" - 5.5"
Power Point 150 .373 3,200 3,410 0 - 2.6" - 5.6"
Accubond CT 160 .512 3,050 3,306 0 - 2.7" - 5.9"
XP3 160 .512 3,050 3,306 0 - 2.7" - 5.9"

Reloading

7mm WSM Reloading Specifications:
Bullet Diameter = .284".
Maximum Case Length = 2.100".
Trimmed Case Length = 2.090".
Primer Size = Large Rifle.

7mm WSM Accuracy Reloading:
Accuracy, Brass, Primers, Powder, Bullets, Load Testing, Run-Out.

 For the Antelope, Hog, Blacktail, Whitetail or Mule Deer hunter hand-loading or reloading his or her own 7mm Winchester Short Magnum ammunition, Western Powders, Ramshot Magnum rifle powder does an impressive job of launching 139 grain .284" diameter bullets at high velocity. Ramshots online reloading data shows that a 139 grain .284" diameter Hornady SST bullet using 69.0 grains of Ramshot Magnum powder can be driven to a velocity of 2,921 feet per second loaded at a maximum cartridge overall length of 2.850" in the 7mm WSM. This load does not top out until the 139 grain bullet is at 3,245 feet per second at a chamber pressure of 58,960 P.S.I..

 For the 139 grain bullet reload if you sighted your 7mm Winchester Short Magnum hunting rifle in dead on at 235 yards it would only be 2 inches high at 150 yards and only 3.7 inches low at 300 yards which would be an excellent Antelope, Hog, Blacktail, Whitetail or Mule Deer load for the 7mm WSM.

7mm WSM Load Data:
Test Powder Used = Ramshot Magnum.
Test Bullet Used = Hornady / Type = SST / Diameter = .284".
Test Primer Used = Winchester WLRM.
Test Case Used = Winchester.
Test Case Trimmed Length = 2.090".
Loaded Cartridge Overall Length = 2.850".
Test Barrel Length = 24".
Test Barrel Twist Rate = 1 in 9".
Hornady
Bullet
Weight
Grains
Hornady
Bullet
Sectional
Density
Hornady
Bullet
Ballistic
Coefficient
Powder
Start
Load
Grains
Start
Load
Velocity
Fps.
Powder
Maximum
Load
Grains
Maximum
Load
Velocity
Fps.
Maximum
Load
Pressure
P.S.I.
139 .246 .486 69.0 2,921 76.7 3,245 58,960
Short Range Ballistics Chart For Above Load:
Recommended
Cartridge
Usage:
Bullet
Weight
Grains
Bullet
Ballistic
Coefficient
Muzzle
Velocity
Fps.
Muzzle
Energy
Ft. Lbs.
Rifle
Zero
100 Yds.
Bullet
Drop
200 Yds.
Bullet
Drop
250 Yds.
Big Game 139 .486 3,245 3,250 0 - 2.3" - 5.0"
Long Range Ballistics Chart For Above Load:
Range: 100 yds. 200 yds. 300 yds. 400 yds. 500 yds. 600 yds. 700 yds.
Velocity Fps. 3,038 2,841 2,653 2,473 2,299 2,133 1,973
Energy Ft.Lbs. 2,849 2,492 2,173 1,887 1,632 1,404 1,201
Trajectory: + 1.1" 0 - 5.4" - 15.8" - 31.9" - 54.6" - 85.0"
Maximum Effective Range For Thin Skinned Big Game: 700 Yards.


.28" Caliber
7mm-08 Rem.
280 Rem.
7mm Rem. Mag.
7mm WSM

Short Magnums


Guns Directory:
Rifles
Ammunition
Rifle Dies
Rifle Brass
Rifle Bullets
.17 HM2, .17 HMR, .17 WSM, 5mm Rem. Mag., .22 BB Cap, .22 CB Cap, .22 Short, .22 Long, .22 LR, .22 WRF, .22 WMR.
17 Rem., 204 Ruger, 22 Hornet, 222 Rem., 223 Rem., 22-250 Rem., 220 Swift, 223 WSSM, 243 Win., 6mm Rem., 243 WSSM,
240 Wby. Mag., 250 Sav., 257 Roberts, 25 WSSM, 25-06 Rem., 257 Wby. Mag., 6.5 x 55mm Swedish Mauser, 260 Rem.,
6.5mm Rem. Mag., 264 Win. Mag., 6.8 Rem., 270 Win., 270 WSM, 270 Wby. Mag., 7mm-08 Rem., 280 Rem., 7mm Rem. Mag.,
7mm WSM, 30-30 Win., 308 Win., 30-06 Sprg., 300 Win. Mag., 300 WSM, 300 Wby. Mag., 325 WSM, 338 Win. Mag.,
340 Wby. Mag., 357 Mag., 44 Rem. Mag., 444 Marlin, 45-70 Government.