Ultratech Intermediate Rounds?

[weby]

Gurps seems to use the half weight for all caseless rounds as the base value. It works fine for rifles but produces "funny" results for things like pistols.

As example the 10mm pistol has the whole round as 0.014 lb and even if the propellant was weightless the 0.014 lb is only 98 grains and currently a typical 10mm pistol round has 125 to 180 grain bullets...

[Varyon]

Originally Posted by weby

Gurps seems to use the half weight for all caseless rounds as the base value. It works fine for rifles but produces "funny" results for things like pistols.

As example the 10mm pistol has the whole round as 0.014 lb and even if the propellant was weightless the 0.014 lb is only 98 grains and currently a typical 10mm pistol round has 125 to 180 grain bullets...

I'm not certain where they got the presumed 0.028 lb bullet from, as looking at all the rounds in HT (yes, I know that was published after UT, but presumably they based UT rounds off of existing ones, just like HT used existing ones) shows all the cased 10mm or .40 cal bullets weighing substantially more than that (some of the powder-and-shot .40 cal weigh 0.028 lb, but those don't have cases). Basing it off of some existing .40 cal bullets probably wouldn't be too far off with a WPS equal to half the cased one.

[Anthony]

Originally Posted by Varyon

I'm not certain where they got the presumed 0.028 lb bullet from.

Possibly some (unpublished) gun design system; there was one way back in playtest that got scrapped. I tried building it with GURPS Vehicles for 3e, no luck (got a wps of 0.019 for caseless, not 0.014).

On the other hand, given that a a 20 round magazine of 10mm( heavy pistol) is weight 0.7 and a 30 round (machine pistol) weighs 1, 0.014 seems unlikely anyway (oddly, the 40 round also weighs 1).

[clu2415]

The next rifle the US military adopts will be either ceaseless or semi-caseless: telescopes bullet, plastic case, with or without a brass base to seal the chamber. Look up the LSAT demonstrator. After you have reduced the weight of ammunition, then you have extra carry weight available on all your soldiers. You can either give them more rounds or a more powerful round that will have the same weight as the old brass-cases round. Since you are designing ammunition and weapon from the ground up, design it to use very low drag bullets and you will deliver more energy to the target for a given amount of recoil.

Once you look at the Ultra-Tech weapons from this viewpoint, you see that 7mmCL is the replacement for 5.56; the Storm Carbine is a caseless AK-47, and 10mmCLR is a caseless, beefed up 7.62x51mm.

[sir_pudding]

Originally Posted by clu2415

The next rifle the US military adopts will be either ceaseless or semi-caseless:

That's optimistic. I'd be willing to bet that there's at least one new version of a current service rifle or carbine that gets issued before any caseless weapon enters production.

[Anthony]

Originally Posted by clu2415

The next rifle the US military adopts will be either ceaseless or semi-caseless.

Depends a lot on what you mean by 'next rifle'. I wouldn't be surprised by an M16A5 or M4A2. The big thing, though, is that improving rifles is actually pretty far down on the list of priorities for the military, and changing from 5.56x45 would be a great big logistics headache. Most likely next-gen is polymer-cased 5.56, and even that is on the edge; there are some fairly fundamental challenges to making caseless or light cased ammo that is stable and durable enough to work in an automatic or semi-automatic rifle configuration.

[sir_pudding]

Originally Posted by Anthony

Depends a lot on what you mean by 'next rifle'. I wouldn't be surprised by an M16A5 or M4A2.

Or an M2010A1, or an M107A2 (especially likely given the XM500 program).

[Fred Brackin]

Originally Posted by Anthony

there are some fairly fundamental challenges to making caseless or light cased ammo that is stable and durable enough to work in an automatic or semi-automatic rifle configuration.

It could be even worse than that. The "next rifle" with novel ammo may not happen until someone makes a reliable SAW that gets a lot of benefit from lighter ammo. Once you have that "killer app" SAW then you get the rifle too for ammo compatibility.

[Anthony]

Originally Posted by sir_pudding

Or an M2010A1, or an M107A2 (especially likely given the XM500 program).

The constraints for a sniper rifle are significantly different from the constraints for an assault rifle, somewhat more finicky ammunition is tolerable, though on the reverse side of that ammo weight is also less of a constraint. Still, I'd bet on the next step being saboted ammunition, not caseless.

[weby]

Originally Posted by Varyon

I'm not certain where they got the presumed 0.028 lb bullet from, as looking at all the rounds in HT (yes, I know that was published after UT, but presumably they based UT rounds off of existing ones, just like HT used existing ones) shows all the cased 10mm or .40 cal bullets weighing substantially more than that (some of the powder-and-shot .40 cal weigh 0.028 lb, but those don't have cases). Basing it off of some existing .40 cal bullets probably wouldn't be too far off with a WPS equal to half the cased one.

A .40 s&w can go down to 0.027 lb total for a light bullet... a 0.028 would be something like a 110-115 grain bullet for that with the original subsonic load. Currently the normal load is sightly larger and a 165 to 180 grain bullet is normal though resulting in something like 0.038lb/round. But even halving that 0.038 produces too low result as a caseless version would still likely fire the 180 grain bullet alone is thus about 0.026lb and then you add the propellant.