New 7.62x40 WT - .223 necked up to .308


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bds
August 24, 2011, 10:13 PM
In September issue of Shooting Illustrated, they discuss Wilson Combat's new 7.62x40 cartridge that's essentially .223 necked up to .308.

Primary benefit is the need to only change your AR barrel and magazine while being able to use all other existing components.

125 gr bullet out of 16" barrel produces 2400 fps.

Any thoughts and/or comparison to 6.8 SPC shot from same 16" barrel?.

Article also hinted heavier bullet loads for suppressed fire application ...

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Michael R.
August 24, 2011, 10:21 PM
i do not own a rifle in 6.8 but here are my thoughts. in my reloading manual, the maximum velocity for the 6.8 spc with a 115 grain bthp is 2579 fps. but with a 125 grain bullet i would feel that the 7.62x40 wt would be a little faster than the 6.8 spc.

Michael R.
August 24, 2011, 10:23 PM
also, those figures were taken from a 24 inch barrel, confirming that the 7.62x40 is superior to the 6.8

68wj
August 25, 2011, 04:56 PM
It's a good option is you want to keep your 5.56 mags and bolt. Fired 5.56 brass is common but has to be formed and .30 cal bullets are plentifull.

Performance from Wilson Combat's own ammo:
7.62x40 WT
110 gr. Sierra HP, 2425 FPS - 16" Barrel
110 gr. Sierra HP, 2525 FPS - 18" Barrel
125 gr. Nosler Ballistic Tip, 2350 FPS - 16" Barrel
125 gr. Speer TNT, 2400 FPS - 16" Barrel

6.8 SPC
95 gr. Barnes TTSX, 2850 FPS - 16" Barrel
110 gr. Hornady BTHP, 2700 FPS - 16" Barrel
110 gr. Barnes TSX, 2700 FPS - 16" Barrel

Breakmyfootoff
August 25, 2011, 11:10 PM
How does this compare to 300 aac blackout? It sounds really similar.

1stmarine
August 25, 2011, 11:38 PM
For the best possible ballistics with the same bolt look at the 6x45.
The best bullets translate to flatter shooting and more energy at all ranges.
The only advantage I see with the blackout and wisper is the subsonic option with 220gr bullets. Can also do with the AK round.
shoot often, shoot safe.

Pigoutultra
August 26, 2011, 08:11 AM
For the best possible ballistics with the same bolt look at the 6x45.

Are you referring to the wildcat, or the 6x45 Kimber?

1stmarine
August 26, 2011, 08:13 PM
6x45 offspring of the .223 rem. basically the .223 rem necked up to 6mm.
Last weekend I got....
90gr SMKFMJ ... 2780fps.
87 Hornady Amax.... 2792fps
100gr SGK....2675fps.

Cannot do more at the moment, anyway to be honest, I am already very happy but I am still researching with a new barrel and ball powders. I am also building an ACC blackout for subsonic mainly and will compare with the 7.62x39 also subsonic.

I am documenting here and will start another one for the ACC as soon as I can get to it, in case anyone is interested...
http://www.thehighroad.org/showthread.php?t=564287

sixgunner455
August 26, 2011, 08:23 PM
1stmarine, did you have a typo on that 100gr 6mmx45 load? It looks like you went from just under 2800 fps for the 87 and 90 gr loads to just over 1600 fps for the 100 gr.

1stmarine
August 26, 2011, 08:48 PM
yes it is 2.6K sorry that! and Thanks!

Also I forgot I have two new barrels. One arrived today and one on its way... I am going to try 24" with superformance powder and a lower Rate of twist.
Sorry to the OP I don't mean to hijack this thread so anyone with interest in .223 offsprings any learning's I am sharing the best I can as time allows.

Zak Smith
August 26, 2011, 09:36 PM
Anything in .30 caliber based on the .223 case and limited to AR-15 magazine COAL will be substantially identical to .300 Fireball, .300 Whisper, .300 Blackout.

1stmarine
August 26, 2011, 09:49 PM
That is what I think. Even with the VLD magazines that allow a substantial increase in COAL you will be limited by chamber specs and the design of the case itself that needs a good portion of the massive bullet (For AR-15 I mean) to be properly seated to assure good tension. Not much meat on the brass there.
So, like always, we go up but gravity pull us back where we were before.
Simple physics.

gotzero
August 27, 2011, 10:04 AM
The Wilson round needs new magazines I believe.

The shorter rounds make a little more sense to me. Use the stock mags, create the .300 necks from the wider part of the brass, great subsonic performance, etc. I do not have one but I decided to get a barrel, it would be nice to replace as little as possible.

The disingenuous comparisons from mfg's are getting very old. No one is going to use lower velocity rounds out of 24" barrels...

sansone
August 27, 2011, 10:33 AM
For the best possible ballistics with the same bolt look at the 6x45.
The best bullets translate to flatter shooting and more energy at all ranges.
The only advantage I see with the blackout and wisper is the subsonic option with 220gr bullets. Can also do with the AK round.
shoot often, shoot safe.
this makes perfect sense to me. I play with loads for .243 anyhow and putting a 90gr pill on top a .223 case just seems "right"

Tirod
August 27, 2011, 11:08 AM
The affect of increasing bullet diameter in the same case allows the base to be exposed to more pressure. That increases the amount of kinetic energy it "absorbs" and puts more power downrange. It also expends it more quickly because of more frontal area and potentially less efficient shape. The heavier bullet is also affected by drop to more significant degree, delivering less effective range. Friction and gravity overcome it earlier.

There is no "superior" in choosing the ballistics of a bullet - you pick the one that dynamically meets the taskings for that job, in range, impact, penetration, etc. Given equal barrel lengths and bullet weights, the .30x.223 will generally have less range and more power than 6.8SSPC, and that cartridge will generally have less range and more power than 6.5G. That is a generalization, it will get picked to death by fanboys, but the harsh reality is that when you baseline performance factors like barrel, weight, and OAL of the cartridge, you get that.

Whatever, understand what the cartridges OPTIMUM application is, and don't make more of it than it is. It can either do the job well, or just do the job - nothing morally wrong with middle of the pack performance - but it CANNOT be the answer to all applications. It WILL run short at one end or the other of it's power curve, and another cartridge exists to easily better it.

Go fanbois all over it and claim "superiority," and a true appreciation of what it can really do will get buried in a rising tide of nitpicking. No cartridge is "superior," it just has more power or speed at a certain time in it's flight, and might offer some advantages in logistic outside it's ballistic envelope. Performance is purchased in dollars, what one shooter decides for himself is his business.

Pigoutultra
August 27, 2011, 01:48 PM
I do like the idea for this cartridge, but it has been done before. Not much new here 'cept for a new name.
That being said, I like it when companies try to reinvent the wheel, so to speak, they just might make it better.

bds
August 28, 2011, 03:16 AM
Well, I have a 20" Bushmaster HBAR and 16" .308 Saiga. Happy with both in accuracy (1-1.5" @ 100 yds).

I thought about 7.62x39 or 6.8 SPC 16" upper and saw the 7.62x40 WT article.

Looks like it's a No-Go and I prefer to have a complete upper that I can swap out.

Thanks for the comments!

helotaxi
August 29, 2011, 06:26 AM
The 7.62WT is different than the .300AAC and the Whisper. The case is longer and has a higher capacity. It was designed to perform better than the other two with supersonic loads using lighter, shorter bullets. The Blackout and Whisper were designed primarily with subsonic performance in mind.

Wilson does use a modified magazine for their round. They are Lancer or Tangodown (don't remember which) with the internal ribs ground down. The ribs in normal AR mags intrude too far into the mag body for the .30 cal bullets to stack correctly. The solution with the Blackout and Whisper is to seat the bullet a bit deeper, but the longer case of the WT eliminates that option.

dom1104
August 29, 2011, 06:31 AM
in my mind...

the WT round is for making major in USPSA.

The Blackout is for general use / suppressors.

Special mags are the downfall of the WT round.

bds
August 29, 2011, 09:46 AM
the WT round is for making major in USPSA.
I may consider shooting 3 gun in the future with a 16" upper. What is the general consensus among 3 gun shooters?

Thanks.

kentucky_smith
August 29, 2011, 09:49 AM
Special mags are the downfall of the WT round.


I use plain GI 20 rounders just fine at full capacity. 30 rounders can't quite get that many in there.

CMC
August 29, 2011, 10:02 AM
If you are buying a complete upper and only looking at 100 yards I myself like the 30 remington AR , It requires a new magazine and it is a single stack.
Mine is very accurate even with factory loads and if you reload you can load the Sierra 135 BTHP for fun and you can load it to about 2550 fps from a 22 in barrel.
For hunting I use the Nosler 150 gr ballistic tip and it does have some punch.
Here is a link on an NRA article on reloading the cartridge.
http://www.americanrifleman.org/articles/handloading-30-remington-ar/

Good luck

GunTech
August 29, 2011, 10:14 AM
Another solution to a non-existant problem.

helotaxi
August 29, 2011, 10:46 PM
Another solution to a non-existant problem.

All problems were solved back in the late 1800's. There have been hundreds if not thousands of cartridges designed since then that were solutions to non-existent problems.

Reality is that it fills a very small specific niche. Not a problem, but a narrowly defined desire. Of course I personally consider unfulfilled desires a problem but maybe that's me. This one isn't my particular desire, but apparently it was for someone.

Tirod
August 30, 2011, 10:55 AM
If you want to hunt with an AR, and 5.56 is illegal in your state, big problem. You have no choice but an alternate caliber. This could solve the problem, and Wilson has done sufficient research to expect a profit can be made.

Magazines are caliber, action, even brand specific. Most aren't interchangeable between different pistols, or rifle to rifle. It's just the unique nature of the AR that makes shooter require it - and if it's not 5.56, a different mag is no big deal. Experienced gun owners know that is part and parcel to the whole hobby.

There was a time when almost no American owned a .30 gun, and there will be a time when most won't. It's base diameter is on the extreme large end of working intermediate calibers - the US hasn't ever used it for that except the M1 Carbine, and that's a stretch. In foreign use, the caliber is noted for mediocre performance - it's largely an addiction to tradition, not ballistics, that keeps it popping up in new cartridges.

Reducing the base diameter makes for a more aerodynamic bullet - I see the under 7mm as having the sweet spot in ballistic performance in the AR mag length. The .308 lost the fight keeping it's place in assault rifle use, most cartridges were just too powerful for what was needed. Now it's time to accept that the .30 is just too large a bullet in the AR.

It doesn't mean somebody can't sell a few while the public takes it's sweet time figuring it out.

HB
August 30, 2011, 03:12 PM
I'll just stick to an sks with tech sights. With good ammo it will shoot with many open sighted ARs if you are proficient and practice. At 200 yards and under a deer is toast.

It seems to me all the .30 cal AR rounds do what a x39 or 30-30 does with more ammo cost unless you really like ARs.

HB

m33p0n3
August 30, 2011, 03:56 PM
I'll try and find the source, but an article I read basically explained it as divergent from the AAC Blackout development. It's essentially the same as the blackout/whisper cartridge, but trades a little more supersonic velocity while giving up subsonic.

bds
August 31, 2011, 03:37 AM
FWIW - http://www.wilsoncombat.com/762x40WT.htm

The 7.62x40 WT was designed around an optimal overall cartridge length of 2.250” which is a perfect fit in the new Lancer L5 AWM magazine and allows for proper case neck to bullet fit. Therefore the barrel throat was optimized for this overall length and the 7.62x40 WT does not suffer from the same inconsistent accuracy issues in the AR platform often seen with the 300 Whisper and 300 BLACKOUT.

http://www.wilsoncombat.com/images/762x40/762x40-comparison.jpg

7.62x40 WT (Wilson Tactical)
Project Goal - Develop an inherently accurate and low recoil cartridge in the immensely popular .30 caliber that has more terminal effectiveness than the 5.56 while utilizing as many standard AR platform 5.56/.223 components as possible.

Cartridge Application - Designed for tactical/defense applications as well as hunting for medium sized game such as deer and feral hogs. The 7.62x40 WT (Wilson Tactical) has very useful tactical applications with soft point and hollow point bullets providing reliable terminal performance on soft tissue while the Barnes TTSX will easily penetrate tough barriers. For hunting the 7.62x40 WT vastly out performs the 5.56 and is on par with the 6.8SPC at ranges out to 175-200 yards. The VERY mild recoil of the 7.62x40 WT also makes it ideal for female and younger shooters as well as anyone that’s recoil sensitive.

Cartridge Specifics - The 7.62x40 WT is based on the inexpensive and readily available 5.56x45 Nato cartridge case. The 5.56 case is shortened to 1.560” and then re-sized (single operation) in a standard 7.62x40 WT sizing die which results in a formed 7.62x40 WT case with a finished overall case length of 1.565”. The cartridge is designed for 110-150gr .308” diameter bullets loaded to supersonic velocities, but if chambered in a 1-8 twist barrel is also suitable for heavy bullet subsonic use also.

Ballistic Performance Comparison

7.62x40 WT (16” barrel)
110gr: 2450FPS Muzzle Velocity and 1466 Foot Pounds of Energy
125gr: 2400FPS Muzzle Velocity and 1599 Foot Pounds of Energy
150gr: 2200FPS Muzzle Velocity and 1612 Foot Pounds of Energy

5.56 Nato (16” barrel)
55gr: 3150FPS Muzzle Velocity and 1212 Foot Pounds of Energy
62gr: 3000FPS Muzzle Velocity and 1239 Foot Pounds of Energy
77gr: 2750FPS Muzzle Velocity and 1293 Foot Pounds of Energy

7.62x39 (16” barrel)
123gr: 2320FPS Muzzle Velocity and 1470 Foot Pounds of Energy

6.8 SPC (16” barrel)
110gr: 2550FPS Muzzle Velocity and 1594 Foot Pounds of Energy

300 BLACKOUT (16” barrel)
125gr: 2275FPS Muzzle Velocity and 1436 Foot Pounds of Energy

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