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Old December 5, 2000, 05:38 PM   #1
Oleg Volk
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Since the main charge against .223 is the lack of enetration on cover and considerable deflection on even the lightest obstacles, how about necking it up? Simply replace the 55gr or 62gr 5.56mm bullet with a 100gr 6.5mm or a 120gr 7.62mm bullet. Would need to change barrels and sights on the AR15, probably magazines as well (I think the neck size matters in double-stacks).

End up with a heavier projectile that penetrates hard cover better, still yaws nastily as any spitzer would, drifts less in cross-wind. Down sides, less fragmentation in the tissue, more curved trajectory. Do you think that such a change would improve the overall performance of the AR15?
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Old December 5, 2000, 05:58 PM   #2
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Already been done. The usual wildcat is the 6x45mm cartridge-a .223 necked up to 6mm. There's also a 7mm version I believe, though that's probably getting close to a straightwalled case! Problem is that you are losing velocity with each gain in weight. Powder capacity is pretty limited with the .223, I'd hate to see how much it loses with a larger bullet.
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Old December 5, 2000, 06:24 PM   #3
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7mm TCU

The hangun silhouette shootters use this to get more momentum on the long range rams. It has a shoulder and a tiny bit of taper to the case. I've read of people necking that case up to 30 cal but apparently it has just a suggestion of shoulder when stretched that far.
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Old December 6, 2000, 05:05 PM   #4
Ought Six
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SSK Industries, makers of custom barrels for T/C Contenders and Encores, has several wildcat calibers based on a 'necked-up' .223 Remington case. They call these the 'Whisper' calibers, as the first one, .300 Whisper, was designed to launch a 240 grain (!) Sierra Matchking bullet at just below the speed of sound for use in silenced weapons. You can order a silenced .300 Whisper barrel for a T/C Encore from them. For a while, they were making suppressed M-16 uppers in .300 Whisper (I *want* one!).

From the SSK Industries website:
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.

Whispers: 6mm, 6.5mm, 7mm, 300 and 338 #2.
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Old December 7, 2000, 11:29 AM   #5
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The 300 Whisper is based on the .221 fireball case which is basically a shortened .223 case with the same case head demensions as the .223. When loaded with a 200 gr. + bullet it will still fit in an AR15 mag.
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Old December 7, 2000, 11:02 PM   #6
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Necking Up

Don't forget, that anytime you neck a case UP, you need to lubricate the inside of the neck with graphite.

I forned quite a few 357 Harret from 30-30 cases.
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Old December 8, 2000, 05:07 PM   #7
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The 6 x 45 mm is the only cartridge I know based on the .223 case that is practical for use in the AR. It reatains the body taper of the .223 Rem. and just necked up to accept the 6mm/.243 bullet. It can be loaded to magazine length, but gives up a lot of case capacity.

The TCU family of cases (6mm, 6.5mm, and 7mm TCU) are not practical for use in the AR. They have a blown out body with very little taper and will not fit through an AR-15 magazine. They are loaded to considerably longer OAL than the .223 Rem. magazine length cartridges.

The "Whisper" cases are based on the .221 Fireball case and can be loaded to magazine length. And will readily feed through an AR mag.

Regards! DaMan

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Old December 15, 2000, 11:49 PM   #8
Keith J
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No, it won't help

The 5.56 NATO is one of the most effective battlefield rounds of the non-expanding (that's a farce, explaination later)types. Dr. Martin Fackler has proved its effectiveness in tissue simulants and correlated this with actual battlefield wounds and sedated animal tests.

Both US incarnations of this caliber (M855 and M193)exhibit the same performance at velocities greater than 2700 FPS which is about 200 yards downrange with the 20" barrel of the A1 or A2. The bullet enters, yaws and breaks into two major pieces with greater fragmentation and smaller pieces at higher velocities (shorter ranges). This performance is only comparable to certain German 7.62 NATO rounds and a certain Eastern Europe 7.62 x 39. All other rounds typically yaw but do not disintegrate and as such, posess less wounding/killing "power". Longer bullets take longer to yaw upon entry in a target and perform like arrows in smaller targets. Larger diameter bullets only increase the entrance/exit holes. The main damage occurs when the projectile has yawed 90 degrees from the original flight path. Yawing bullets were not designed for this purpose but rather this fact was discovered after the fielding of these types. As such, no one has ever pursued the clause of "excessive damage" as it pertains to small arms.

There is a myth arising from Somalia where Rangers were outgunned and opposing forces were not dispatched immediately from 5.56 NATO fire. This is attributable to two causes, short barreled 5.56 weapons and M855 ammo. This combination provides 2500 FPS at the muzzle and is beyond what would provide a one shot kill at any range.
Another contributing situation was the physiology of the opponents (emaciated Eastern African body types) and the herb drugs commonly taken which inhibited hypovolemic shock.

If those soliders were equipped with a 20" barrel A1 and M193 ammo, things would have been much different. A 300 Whisper would have made little difference. Even the M60 had problems in dispatching targets.

IMHO, if I ever had to chose a combat weapon, the M16 A2 would be my only choice. I can carry considerable ammo and it will reach to 600 yards if need be. At that range, it might not knock my opponent down but he will defintely bleed out in the remaining 400 yards.

I have an AR 15 A2 that groups 1/2 MOA out to 400 yards with my handloads. Even M193 groups 1.25 MOA out to 300 yards and that's with a 1:7 twist chrome plated bore. I don't have any M855 for longer range testing but I'm sure it will be under 2 MOA at 600 yards.
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Old December 16, 2000, 11:51 AM   #9
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The .300 Whisper, as it's name implies, was developed for use with suppressors. It will shoot heavy bullets at sub-sonic speeds thus eliminating the supersonic "crack". It will also feed through the M-16 magazine. It has a trajectory like a rainbow.

The 6x45mm (6mm-223) used to be fairly popular. Many shooters had their AR's or Mini-14s rebarreled to this caliber for deer and other medium game. The 6mm-223 isn't more effective than the .223 Rem. for this purpose, but many states have a 6mm (.243) minimum caliber requirement for deer hunting.

The bullet companies could design a .223 bullet that would be more effective on medium game, but since the .223 is not allowed for deer in most states, why bother? A bullet of 60-65gr. would provide the best bullet weight to velocity ratio for this purpose. This would provide the best penetration and weight retention on soft targets, if used in a properly designed hollow point/soft point bullet

Regards! DaMan
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Old December 16, 2000, 02:42 PM   #10
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If anyone wants more info, go over to and click on "forums"....scroll down till you see "Kurts Kustom Firearms". He has something called the '30 KKF Hush'....(aka 300 Whisper) and Hess Arms has one too. Ask Kurt about his 'round'.

Any how, if I recll, about a week ago, someone asked how much a AR barrel would be w/ gas block. I think it was somewhere in the 300ish range...don't quote me.

The 50th Anniversary Edition of Sierra Handgun reloading has the 300 Whisper in there, for T/C barrels.

Just an FYI...

Happy Holidays all
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