CT Ammo Update

[stanc]

As I expected, 6.5mm CT is as bulky and heavy as 7.62mm CT.





6.5mm CT carbine needs more development. Current weight is as heavy as an M1 Garand, and it's two inches longer than an M4 carbine, despite having a barrel that's two inches shorter.





7.62mm CT machine gun looks good. Weighs 14.7 pounds, and convertible to 6.5mm.









http://www.dtic.mil/ndia/2016armament/18...illips.pdf

http://www.thefirearmblog.com/blog/2016/...s-program/

[LRRPF52]

200rds of 6.5mm CT will weigh what 100rds of linked 7.62 NATO M80 currently does, or less.

That's a huge significance for logistics at the micro and macro levels.

I'm only seeing positives, not negatives.

[stanc]

200rds of 6.5mm CT will weigh what 100rds of linked 7.62 NATO M80 currently does, or less.

That's a huge significance for logistics at the micro and macro levels.

I'm only seeing positives, not negatives.

Well, you're exaggerating a bit, in that it's more like 160 rds of linked 6.5 CT vs 100 rds of linked 7.62 NATO, but yeah, for the 6.5 CT machine gun, it looks to be all good.

For the 6.5 CT carbine, not so much. Much heavier and a bit longer than the M4, with 20-rd magazines that are fatter than, and just as tall as, 30-rd 5.56 magazines.

[VASCAR2]

I'm curious if the CT 6.5 could be put into a Bullpup, it might make an ambidextrous Bullpup to heavy. Neat stuff thanks for posting Stan.

[LRRPF52]

Well, you're exaggerating a bit, in that it's more like 160 rds of linked 6.5 CT vs 100 rds of linked 7.62 NATO, but yeah, for the 6.5 CT machine gun, it looks to be all good.

For the 6.5 CT carbine, not so much. Much heavier and a bit longer than the M4, with 20-rd magazines that are fatter than, and just as tall as, 30-rd 5.56 magazines.

No, I didn't exaggerate. If you look closely in the charts, they are talking about a different 7.62 NATO load with a 130gr projectile, which weighs less than M80 147gr, which is what I'm used to carrying.

I have no interest in the carbine at this stage. The LMG is where it is at for CT.

100rds of 7.62 M80 linked is 7lbs. You tend to remember these things when you've been a Gunner, Assistant Gunner, or Ammo Bearer. When you're the AG and AB in one man, you really remember them. Wish I had pictures, but it's funny how you never see pictures from guys in Weapons Squad with rucks on.

[stanc]

No, I didn't exaggerate. If you look closely in the charts, they are talking about a different 7.62 NATO load with a 130gr projectile, which weighs less than M80 147gr, which is what I'm used to carrying.

100rds of 7.62 M80 linked is 7lbs. You tend to remember these things when you've been a Gunner, Assistant Gunner, or Ammo Bearer. When you're the AG and AB in one man, you really remember them.

My mistake. I didn't read your post carefully enough. However, a weight comparison with 147gr M80 doesn't seem particularly relevant when the new standard is 130gr M80A1.

I have no interest in the carbine at this stage. The LMG is where it is at for CT.

The Army has interest in the carbine. That's what counts.

[stanc]

I'm curious if the CT 6.5 could be put into a Bullpup...

Just offhand, I don't know of anything that would prevent a CT bullpup, but I can't say for sure.

[SHORT-N-SASSY]

I'm curious if the CT 6.5 could be put into a Bullpup, it might make an ambidextrous Bullpup to heavy. Neat stuff thanks for posting Stan.

[SIZE="3"]Actually, Canada is working on a Bullpup rifle using Cased Telescoped (CT) technology:
http://www.casr.ca/bg-future-small-arms-research.htm
http://www.gizmag.com/smart-gun-evolutio...pon/36091/


[/SIZE]

[stanc]

Interesting. Looks like it has an integral suppressor. And mag-fed (semi-auto?) grenade launcher.

Also looks even more ungainly than the US XM26 OICW.





I wonder if they've started work on a 6.5mm version, yet?

[SHORT-N-SASSY]

[SIZE="3"]"Maybe a new Canadian Smart Gun chambered for 6.5mm?"

(http://www.casr.ca/bg-future-small-arms-research.htm)
[/SIZE]

[JASmith]

Nathaniel Fitch posted an interesting discussion about the CT initiative in The Firearm Blog: http://www.thefirearmblog.com/blog/2016/...Newsletter

His sentiments about the path being taken -- sacrificing mobility for long range effectiveness in every rifle -- should resonate with those who have actually had to hump rifles and ammunition into combat.

[stanc]

Textron Systems unveiled its new 6.5mm case-telescoped carbine at Modern Day Marine 2016.

The weighted model represents Textron’s latest effort to develop a new age of infantry weapons that fire weight-saving, case-telescoped ammunition.

Textron has made significant advancements in this technology with its Light Weight Small Arms Technology, or LSAT – an Army funded program that has so far yielded working lightweight machine guns in both 5.56mm and 7.62mm.

The new 6.5 CS carbine emerged out of an intermediate caliber study Textron conducted in 2014, according to Ben Cole, project engineer.

Currently, the empty weight of the mock-up carbine is 8.7 pounds. A magazine loaded with 20 rounds of case-telescoped 6.5mm ammunition adds one pound. An M4A1 weighs 7.74 pounds empty and about 8.74 pounds with a loaded 30-round mag.

Case-telescoped ammunition is about 40-percent lighter when you compare it to the standard brass ammo in the same caliber, Cole said.

The 123 grain 6.5mm has a muzzle velocity of about 3,000 feet per second, Cole said.

Comparatively, the 62 grain bullet on the M855A1 has a muzzle velocity of 2,970 feet per second, according to U.S. Army data.

“If you take this 6.5mm bullet at our muzzle velocity, it’s 300 percent more down-range energy than the M855A1,” Cole said. “So for a minimal weight gain, you would have significantly more down-range lethality.”

Textron officials hope to have a working prototype to begin testing early next year, Cole said.

“We are trying to go after the next requirement for soldier rifles,” Cole said.

http://kitup.military.com/2016/09/textro...rbine.html

The weight of the 6.5 CT carbine has been cut. It's no longer as heavy as an M1 Garand. It's now as light as an M14 rifle.

Still has the same 20-rd mag capacity of the M14, though.

Muzzle velocity is MUCH higher than I think anyone here would have imagined. What are felt recoil and full-auto controllability going to be with 123gr @ 3000 fps??? :eek:

[stanc]

Photo of 6.5 EPR round (via Tony Williams).

https://forums.delphiforums.com/autogun/...g=6778.141

Looks like a very conservative, tangent ogive.

[BluntForceTrauma]

Good find, Stan, although I see no reason they couldn't streamline the nose.

[stanc]

Good find, Stan, although I see no reason they couldn't streamline the nose.

John, as shown in the OP, it looks like development did start with a very streamlined bullet (123gr MatchKing, or similar).

I'd guess that such a long ogive design proved problematical in some manner. I don't know why it was done, but I've seen speculation that:

- Perhaps the long jump to the rifling cause accuracy issues with a long-ogive projectile.
- The shorter ogive enabled better bullet stability in the transonic region.
- A weight of 123 grains was desired, which could not be achieved with a long-ogive, lead-free bullet while keeping length below 5.5 calibers.
- The ogive was chosen for optimum compatibility with a Tracer bullet.

[BluntForceTrauma]

Looking at the photo and thinking about it, you could be right. CT ammo would rewrite the rules about how a bullet goes from case to barrel.

[stanc]

Latest info via Tony Williams

Cartridge
Bullet weight: 125 grains (8 grams)
Muzzle velocity: 2,800 fps (850 m/s)
Cartridge weight: 240 grains (15.6 g)
Cartridge dimensions: 0.5" (12.7mm) diameter x 2" (51mm) length

Carbine
Empty weight 8.7 lbs / 3.95 kg (heavy barrel), or <8 lbs / <3.6 kg (standard barrel)
Loaded 20-round magazine: 1 lb / 0.5 kg
Barrel length (excluding chamber): 14.5" / 370 mm (equivalent to 16.5")
Overall length (stock retracted): 32" / 813 mm
Operation: gas piston, rising chamber
Firing rate: 600 rpm

http://forums.delphiforums.com/autogun/m...g=6622.123

[LRRPF52]

There is a ton of information on the TFB interviews with the program manager.

Many technical details have emerged that are rather interesting, and have potential implications that would turn the entire metallic case industry on its head.

There's a polymer plug up front that the bullet seats in, which seals the breech under pressure. They are seeing better accuracy because it's easier to make a concentric polymer plug than brass, and the projectile is not exposed, so no opportunity for applying force to the side of the projectile during feeding.

The propellant is conventional powder, only highly compressed as close to a solid as possible, which improves performance in both ES and velocity.

She also gives the history and initial vision of the project. There are 3 parts already, with weekly updates.

http://www.thefirearmblog.com/blog/2017/...iscussion/

[Essayons]

I'm curious if the CT 6.5 could be put into a Bullpup, it might make an ambidextrous Bullpup to heavy. Neat stuff thanks for posting Stan.

I have read that the LSAT LMG and carbine both use a rising chamber design. I see no reason it couldn't be used in a bullpup. The Steyer ACR was a rising chamber bullpup with cylindrical case-telescoped ammunition.

I think the rising chamber design is why the barrel of the LSAT carbine is short compared to an M4. The chamber is separate from the barrel and probably isn't included in the barrel length. The M4's chamber is included in the barrel length because it is part of the barrel.

Anyone have photos of a field stripped LSAT carbine or LMG. I'd love to see that.

ETA: Those TFB interviews are really great, LRRPF52. I haven't finished reading them yet, but this part is interesting:

TFB: You obviously have to have a separate chamber and a separate barrel unit. One thing that might be a negative is that on a revolver you have a gap there, where gas can escape. Do you have that problem, or have you found a solution to that?

KP: For case telescoped, the front of the cartridge actually seals the breech, and the plastic flows into the empty space. It’s sort of a balancing act to let the cartridge expand and flow, but not so much that you can’t get the case out of there. It obturates the chamber just like it would with a brass case.

This is also interesting. It may explain why the 6.5 CT ammo weighs almost as much as 7.62 CT ammo:

TFB: Originally, LSAT focused on a 5.56mm weapon, but now the focus with CTSAS appears to be a 6.5mm weapon. How did this change come about? Was it a decision from the Infantry School, or an internal development by CTSAS? Is the 6.5mm now the focus of CTSAS, or a side project?

KP: Based on the success of the original 5.56mm CT system, we were given funding from the Army to pursue a Medium Machine Gun (typically 7.62mm) and a Carbine. The 6.5mm ammunition came about as a result of an optimization study that was done strictly for the CT configuration. Both new weapon systems can be used with either a 7.62mm CT cartridge or the 6.5mm CT cartridge.

* * *

TFB: The 6.5mm CT according to LSAT’s slides weighs 15.4 grams per shot, compared to the 12 grams per shot of brass-cased 5.56mm. In a couple of articles I wrote, I examined the weight penalty of using a round this heavy as a replacement for both 5.56mm and 7.62mm. Does the CTSAS program consider this weight penalty acceptable, or not? If so, is the idea to reduce the number of rounds carried by the infantryman in exchange for greater effectiveness of the individual projectiles, or is the 15.4 grams just the current state of things, the weight of ammunition expected to decrease with development?

KP: Since the 6.5mm is a heavier projectile than the 5.56mm, and it requires more propellant to achieve the necessary velocity, it will probably always be heavier than the 5.56mm round. This is an option that is being offered for a round that provides considerably more range and performance than even the 7.62mm, so that is actually a better comparison. The trade-off between weight and performance is totally up to the user community, and not the technology developer.

My takeaway from TFB's Kori Phillips interviews is that the LSAT weapons are technology demonstrators. If the technology is adopted, the final configuration (including things like trade-offs between ammunition weight and performance) will be up to the user community.

[stanc]

I think the rising chamber design is why the barrel of the LSAT carbine is short compared to an M4.

:confused: It's not short compared to an M4 barrel.

Excluding chamber, barrel length is 14.5" (same as M4).

Including chamber, barrel length is 16.5" (2" longer than M4).