How does telescoped ammunition work?

[ClydeFrog]

I read a presentation about a possible future squad automatic weapon which would either use caseless ammo or conventional ammunition in "telescoped configuration"? What does that mean? Is the bullet pushed forward inside the cartridge prior to ignition or something? If so, what's the point apar from having a slightly shorter overall length of the ammunition.

Thx in advance.

[RecceGuy]

CTA or cased telescopic ammunition is basically where the projectile is fullly encased within the cartridge case. The cases tend to be the same diameter all the way down ie no shoulders on the casing, it looks like a large beer can The advantages of it are the round tends to be smaller, you dont have as many feed problems and the cannon mechanism can be a lot smaller compared to comparative weapons. The British Army will be fielding a 40mm CTA cannon on the Warrior upgrade due to start this year. I saw this fire at the AFV Gunnery School in Lulworth earlier this year and its fairly impressive!!!

http://i22.photobucket.com/albums/b318/maximus8425/CTAammo.jpg

http://i22.photobucket.com/albums/b318/maximus8425/CTAmech.jpg

http://i22.photobucket.com/albums/b318/maximus8425/CTScannon.jpg

[spoonkilr]

wow that was darn interesting. thanks for that reeceguy.

[ReggayMC]

awesome info.

Very Interesting

I mean, look at the size cutdown in the 40mm shell

[xEDGEx]

Kinda reminds me of the H&K caseless round. Or am I way off course?

[Freibier]

The rotating chamber seems indeed like a direct copy of the HK system

[RGRBOX]

thanks for the info.. i just learned something new..

[ClydeFrog]

Thanks RecceGuy, interesting information.

[RecceGuy]

Kinda reminds me of the H&K caseless round. Or am I way off course?
It's probably a development of it but wasn't the H&K round square and had a combustible case? And at some stage BAE owned H&K so there is bound to be some progression in the work that the firms carried out, just seems BAE have upped the calibre, but I do remember that the H&K breech was a rotating design.
Here found a few pics.

http://i22.photobucket.com/albums/b318/maximus8425/g11_ammo.jpg
These are the rounds for the H&K G11, early cases on left later on right.

http://i22.photobucket.com/albums/b318/maximus8425/g11_feed.jpg
And the feed system, so yeah it's very similiar to the 40mm design.

And finally this is a picture of 40mm CTA cutaway rounds.
http://i22.photobucket.com/albums/b318/maximus8425/PICT0219.jpg

[Hollis]

Recce, thank you. really enjoyed reading about this. By any chance do you have a link, for a more indepth study?

[ktk_ace]

The rotating chamber seems indeed like a direct copy of the HK system

well i'd say its a PARTIAL copy, it cant shoot 3 round burst into the same hole without breaking the law of physics unlike the G11K2

but its a CANNON for F#ck's sake , who needs a 3 round burst ??:roll:

[Durandal]

well i'd say its a PARTIAL copy, it cant shoot 3 round burst into the same hole without breaking the law of physics unlike the G11K2

but its a CANNON for F#ck's sake , who needs a 3 round burst ??:roll:

A 40mm Cannon. You want a high rate of fire, that's its purpose. No one is trying to get rounds down the same hole...just a high rate of fire when needed. 3 HE rounds land in a building is going to do a lot more than a single...

Come on dude...think.

[RecceGuy]

A 40mm Cannon. You want a high rate of fire, that's its purpose. No one is trying to get rounds down the same hole...just a high rate of fire when needed. 3 HE rounds land in a building is going to do a lot more than a single...

Come on dude...think.

I would imagine it can do repetition when needed if you're wanting pinpoint accuracy but as Durandal says if you're firing HE you want to spread it a little for everyone to have a bit and for that to be effective you want a high rate of fire.

[akmarksman]

kinda reminds me of a shotgun slug.

[Major Maxillary]

REminds me of the ammo from some Shirow manga.

[tafkaf]

It's probably a development of it but wasn't the H&K round square and had a combustible case? And at some stage BAE owned H&K so there is bound to be some progression in the work that the firms carried out, just seems BAE have upped the calibre, but I do remember that the H&K breech was a rotating design.
Here found a few pics.

http://i22.photobucket.com/albums/b318/maximus8425/g11_ammo.jpg
These are the rounds for the H&K G11, early cases on left later on right.

http://i22.photobucket.com/albums/b318/maximus8425/g11_feed.jpg
And the feed system, so yeah it's very similiar to the 40mm design.

And finally this is a picture of 40mm CTA cutaway rounds.
http://i22.photobucket.com/albums/b318/maximus8425/PICT0219.jpg

In the pictures it seems that the propellant is packed around the projectile inside the case. How does it work when you fire? In a conventional gun the projectile "seal" the barrel so that the propellant gases don't leak out in front of the projectile. How is that achived in this type of gun?

[RecceGuy]

I would imagine there is some kind of slip ring or sabot type arrangement at the front of the round to provide forward obturation, otherwise as you say the round is going nowhere.

[Durandal]

I would imagine there is some kind of slip ring or sabot type arrangement at the front of the round to provide forward obturation, otherwise as you say the round is going nowhere.

Well yeah, its pictured in the schematic...

http://i22.photobucket.com/albums/b318/maximus8425/CTAmech.jpg

[tafkaf]

Well yeah, its pictured in the schematic...

http://i22.photobucket.com/albums/b318/maximus8425/CTAmech.jpg

I can't see, the resolution is to bad. Can you publish the picture in Hi res?

[RecceGuy]

Well yeah, its pictured in the schematic...

http://i22.photobucket.com/albums/b318/maximus8425/CTAmech.jpg
To tell you the truth I never looked at the pic that closely!! If you save the pic tafkaf then just enlarge it. I tried posting it in hires but it just keeps coming up that size.

[josh10524]

Right click and view image. Works in Firefox.

[tafkaf]

OK, now I see. The sabot goes all the way to the front of the casing and its there were is seals the bore so the propellant gases don leak out in front of the projectile. And the empty case is pressed out by the fresh one beeing chambered. Looks like a good idea.

[Tony Williams]

Ahem: that photo seems to have been copied from my site here - I took the pic myself: http://www.quarry.nildram.co.uk/PICT0219.jpg
It is attached to this article: http://www.quarry.nildram.co.uk/DSEi2003.htm

Some further notes on how cased telescopic works: it is important to ensure that the projectile is firmly inside the barrel before the main propellant ignites. One way to achieve this is to have a two-stage ignition process: the primer (or in larger calibres the primer plus a small quantity of propellant) is separated from the main propellant charge by a partition inside the case. The primer kicks the projectile into the barrel, and only when the projectile is on its way does it uncover a link between the compartments, which allows the primer to ignite the main charge. By the time this gets going there is quite a lot of space behind the projectile which the gas can expand into, and this means that the propllant can be tightly compressed rather than loosely packed as in a normal cartridge. This helps to make the ammo so compact.

The CTA design is not intended to achieve high rates of fire - around 200 rpm is expected. The advantage is mainly ammunition compactness, and the mechanism is designed to be simple and reliable.

Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion forum (http://forums.delphiforums.com/autogun/messages/)