7x46mm vs barrier blind bullets

[Todd.K]

This quote from the 300BLK thread got me thinking and raised a few questions.

As noted during the initial SPC testing in 2002 and as shown in every wound ballistic test of the last 120 years, 7 mm is the most destructive and efficient caliber that can be fit into an assault rifle type cartridge and still have both good intermediate range accuracy (out to 600m or so) and maintain adequate control in short range full auto fire.

I assume testing up to the SPC was done with FMJ.
The SPC and 7x46 were designed and tested with OTM.

Does the recent JAG approval of barrier blind bullets significantly change what the "best" assault rifle cartridge is, or would it just make it better?

Has a caliber, weight, and velocity of a barrier blind bullet that would have ideal terminal performance, increased range, and fit the AR mag size been researched?

Something like a barrier blind bullet in the 6 or 6.5 SPC?

[DocGKR]

"Does the recent JAG approval of barrier blind bullets significantly change what the "best" assault rifle cartridge is, or would it just make it better?"

Nope, just makes it better.

"Has a caliber, weight, and velocity of a barrier blind bullet that would have ideal terminal performance, increased range, and fit the AR mag size been researched?"

Yes, it is called 6.8 mm. If you expand beyond an M4 style platform, then your options open up to things like 7x46mm in a new platform or 7.62x51mm in something like the KAC SR25 EMC.

"Something like a barrier blind bullet in the 6 or 6.5 SPC?"

While 6 mm can be a substantial improvement over 5.56 mm in a short barrel PDW type weapon, I am not generaly too impressed with 6 mm in a general purpose carbine

[Jaws]

With the heavier and higher BC bullets 7x46mm should be much better than 6.8SPC at longer ranges, with a good chance to do the job that needs to be done by both rifles and general purpose .30cal machine guns. Those 35lbs MGs would shrink considerabily if a cartridge like 7mm Murray would be used.
That" comonn receiver" SCAR 17 would be a sweet, easy to modify platform for 7x46mm.

The idea behing 7x46mm is that it could do both jobs decent. carabine and Machine Gun. For machine guns a little better armor penetration is needed to engage harder targets. Barier blind bullets help up to a point, but for general purpose MG you need a bit more energy/destructive power than small bullets can provide.

[Thomas M-4]

FN MK 48 MOD 1 in 7x46mm

[RyanB]

PKM in 7x46.

[kal]

I think we should have had a longer 5.56mm in the first place.

Here's an idea. It can have an MG loading with an AP core, or with a hollow tip to keep the center of gravity as far back as possible and yaw as soon as possible when hitting flesh.

[Jaws]

I think we should have had a longer 5.56mm in the first place.

Here's an idea. It can have an MG loading with an AP core, or with a hollow tip to keep the center of gravity as far back as possible and yaw as soon as possible when hitting flesh.

There's no replacement for displacement. You can tweak a 5.56 all you want. Just isn't enough mass, cross section and energy to do all the jobs required by a main infantry cartridge. You should alsways leave some excess hitting power for times when you have less than ideal conditions.

[Entropy]

There's no replacement for displacement. You can tweak a 5.56 all you want. Just isn't enough mass, cross section and energy to do all the jobs required by a main infantry cartridge. You should alsways leave some excess hitting power for times when you have less than ideal conditions.

+1

One of the primary reasons why the US stuck with the 7.62 caliber long after WWII was its ability to punch through battlefield materials so well. Basically adhering to the concept that it's better to have too much of something than not enough. The Brits got the sweet spot just right with the .280.

I look forward to getting a 7x46 rifle some day. Unfortunately it will be competing with the 7.62 NATO which is just so well established that it would take a massive military adoption of the 7mm to get it anywhere.

[200RNL]

I think we should have had a longer 5.56mm in the first place.

Nice idea, it would function perfectly in a Trapdoor Springfield.

Kidding aside, I think it was the Spanish who developed some cartridges with very long bullets that were fired at moderate velocities. The idea was to duplicate the recoil characteristics of an intermediate cartridge while at the same time duplicating the downrange ballistics (via very high sectional density) of a full power cartridge.

[kal]

One of the primary reasons why the US stuck with the 7.62 caliber long after WWII was its ability to punch through battlefield materials so well.

I don't believe there's a doctrine in the US military today stating that a hand held bullet firing weapon, such as a rifle, must be able to penetrate "battlefield material", like tree trunks and especially urban structural material. The only requirements are certain types of body armor, helmets, and light armor found on light vehicles.

The reason is that fire and maneuver override such a requirement. Furthermore, the materials seen on the field isn't always what it seems. What appears to be a cinder block wall may have its cavities filled with adobe/mortar. What looks like a single layer brick wall may be two layers. And so on, and so on......

I would guess that even 50cal would have a problem with some of these unforseen barriers. In that case, 7.62x51mm or 30-06 would be laughable.