Deer Hunting Forums banner
1 - 2 of 2 Posts

· Administrator
5,531 Posts
some background info on SSK-JDJ (J.D.Jones)

SSK has chambered well over 200 calibers in the Contender. The most popular are the JDJ series which exist in almost every caliber. JDJ cartridges give the highest ballistic performance in each caliber consistent with safety, long gun life and exceptional accuracy. The most popular are the 226, 6 mm, 257, 6.5 mm, 270, and 7 mm JDJ which are based on the very strong 225 Winchester case. The 309, 8 mm, 338 #2, 358, 375 and 416 JDJ are based on the very strong 444 Marlin case. The 6.5 uses 120 grain bullets at 2400 FPS, the 309 uses 165s at 2400 and the 375 uses 220s at 2250, 270s at 2100 and 300 FMJS at 2000 which gives plenty of penetration to take elephant (in 1984 19 elephant were taken with the 375). The 257 gets up to 2900 FPS with an 85 grain to make it the most effective long range varmint caliber for Contenders, and the same load is excellent for whitetail and antelope.

Whispers®: A wide range of calibers encompass the 'Whisper®' series of cartridges. A "Whisper®" cartridge must be capable of sub-sonic extreme accuracy with very heavy bullets for its caliber; i.e. 240 grains in 30, as well as moderate to high velocity while maintaining excellent accuracy with light bullets for the caliber; i.e. 125 at 2300 FPS in 30. The 300 Whisper® was the first of the series, and, contrary to what you may have read about it, the fact of the matter is the cartridge was designed as a multi-purpose cartridge from the beginning. Its design parameters, in addition to the ballistics quoted above, were that it must be capable of being used in the AR-15/M-16 family of rifles, Contenders and bolt action rifles as well as being easily suppressed. I know that because I invented it. It revolutionized the tactical suppressed sub-sonic field in controllability in full auto, power and accuracy. It has been very successful and has gained wide acceptance as a hunting round for mid-size game, such as deer, and has probably taken a wider variety of game than any other handgun cartridge in the same time span. Due to its small case capacity, its recoil is very mild. One Whisper® series from 6 mm, 6.5 mm, 7mm, 300 and 338 is based on the 221 fireball case. Another series is based on the 7 BR case in 338, 375 and 416 caliber to convert 308 case head size actions. Another used the 460 Weatherby case for 50 caliber conversions to 300 Win Mag case head size rifles. Others use rimmed cases, such as the 50-70-750, for use in single shots.

JDJ: SSK's 6.5 Mini-Dreadnought on the 220 Swift case produces 2900 FPS with a 120 and 2700 FPS with a 140 giving it a 300 yard positive deer killing range with very little recoil. The '06 JDJ calibers are highly modified 30-06 cases which generally produce higher velocities than their equivalent belted magnum counterparts in the shorter pistol barrels. We call them Magnum Beaters. The 280 JDJ does 3000 with a 120 and 2850 with a 140. The 30-06 JDJ does 2700 FPS with a 165 { 3200 from a 24"}.The 338 does 2400 with a 250 and 2600+ with a 200, the 358 does 2600 FPS with a 225 and 2700+ with a 180, the 375 does 2400+ with a 270 and 2650 with a 220. The 416 does about 2300 FPS with a 300 and 2200 with a 400. These cartridges are maximized for case capacity and have a short neck and 60 degree shoulder. 15" barrel velocities given.

Wildcats: Creating your own Wildcat is challenging and gives a great deal of satisfaction to the customer. SSK will be glad to help you make up your own cartridge; however, we may already have a reamer in stock that is very close to what you want to create.

Ammunition: SSK is a Cor-Bon distributor of combat and hunting ammunition. Cor-Bon makes Whisper® ammo. We do sell direct to individuals in accordance with existing federal and state regulations. It's true major manufacturers have discontinued various cartridge cases (at least temporarily); however, SSK has a large supply of brass for all JDJ and Whisper® cartridges. There are enough SSK barrels in service that use the 225 Winchester case to enable SSK and others to purchase brass from Winchester in quantity.
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.