This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.
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I have seen that slide before. It does not help me understand what you were trying to say in post #45.
The comparison was based on the same ballistics performance in that doc, that' all.
Okaaaayyyy. But what does that have to do with my comment in post #44, that it doesn't seem plausible for the Textron 6.8mm cartridge to occupy less volume than the SIG and TV 6.8mm rounds?
He wasn't talking about comparison between 6.8CT and 6.8 SIG round, and we don't know whether they share the same performance, argued about 12% volume reduction is pointless.
Another interest point about the 6.8CT, the patent which I referenced in my vid before( https://patents.google.com/patent/US10571232B1).
He wasn't talking about comparison between 6.8CT and 6.8 SIG round
"did textrons entry actually provide a volume reduction compared to others?"
If the "others" are not the SIG and TV cartridges, then which cartridges are?
Another interest point about the 6.8CT, the patent which I referenced in my vid before
Thats an interesting one as it shows a conventional layout. What do you think the significance is there?
I remember reading that presentation when it came out ( I have been following LSAT and CTSAS for a long time). I recall that the lack of details and actual performance numbers reduced my confidence in the findings. It is certainly not terribly difficult to beat the M80A1's velocity and KE at intermediate and long distance.
The big question at this point is how does the current state-of-the-art CT cartridge compare to its state-of-the-art rivals in both weight and magazine size. It might indeed be smaller since it does not need the extra material for a rim. It would be interesting to know.
I am a bit embarrassed that I just now realized that a discussion of cartridge volume must define its terms. The actual geometric volume of a cartridge, ie, how many cc's of fluid it displaces, is not the same thing as the "effective volume" as determined by the size of a 20 or 30 round magazine. For example, although a 6.5 Creedmoor cartridge is geometrically smaller than a 7.62x51 cartridge, a 20-round magazine for each is the same size. The effective volume of a bottlenecked and/or tapered cartridge when optimally oriented in a bulk package may be different yet (overlapping bullet tips, etc.).
I can see how a CT cartridge can claim a lower EFFECTIVE volume than an equivalent bottlenecked one, especially if the assumption is that the "effective volume" of a bottlenecked cartridge is a cylinder of the maximum cartridge diameter with a length that extends to the tip of the bullet. Even if you assume a slight taper to the cylinder, the "effective volume" is larger than the geometric one.
Since the Textron cartridge is fatter than the other two rounds, and nearly as long, it does not seem possible for it to occupy 12% less volume. 12% more volume, maybe.
I don't think so.
The "original" 7.62 mm and 6.5 mm CT were 1/2" in diameter and 2" long, but the current 6.8 mm CT is 12 mm in diameter, and ~2.5" long, so the reduction of volume is around 2.5/2.8, or ~12%.
It seems that the CT round is not loaded with "loose" powder, but with a densified / compressed load.