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Old 11-13-2019, 02:21 AM   #21
johndallman
 
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by AlexanderHowl View Post
Did you also have a 15mm? If so, how did they compare? Was there a preference?
We did not. We had the 25mm, and a 10mm storm carbine each for the rest of the party. Buying these weapons was never an option; we would have had to take big risks to steal another one so we made do with what we had.
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Old 11-13-2019, 08:56 AM   #22
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by Rupert View Post
The Mauser MG 151/20 has a range of 1200/6900, and it's a rather low-powered 20mm cannon, and the M252 has 2400/3300 and is a low-powered 25mm cannon. That a fairly powerful 25mm grenade launcher has Max 2200 is quite reasonable.
Those are machine guns, and they lighter of the two weighs over 90 lbs. I'd hesitate to call either "low-powered cannon" or to use them as a useful basline for the range of a projectile launched from a 1.5 lb weapons system.

As an interesting point of comparison, when I look at the 40mm grenade launcher, range and accuracy drop dramatically, and choosing between a Payload riffle and a 40mm GL is an interesting decision.

Looking at the ATK-H&K M29 from High Tech (page 145) and subtracting out the weight of the underbarrel carbine, it looks like the 25mm launcher should weigh 6 lbs or so. I could see reducing the weight a little with the reasoning that the tech is better, but not to 1.5 lbs. Such a 6 lb weapon is still superior to the riffle in most cases.

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If you want something to be suspicious of, go for the penetration of small calibre shaped charge rounds (and HE, for that matter, but it's not as big an issue with them) in UT - penetration is linear with calibre, which is the general case. However, small warhead use up a disproportionate amount of their available mass and volume in fusing, and thus have less penetration than extrapolation from larger calibres would suggest. The HEMP rounds of 10-18.5mm have this allowed for (but making them imp seems off), but the 25mm shaped charge should arguably also have a penetration modifier of only (5), or reduced base damage.
I'd favor the penetration of (5). That weakens both options, but the GL more.

I still want a heavy grenade launcher that launches 64mm or 100mm warheads 400 yards. Or that gets 2000 yard ranges on 40mm warheads. Of course, those are arguably mortars.
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Old 11-13-2019, 10:12 AM   #23
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Default Re: 25mm Payload Rifle [Ultratech]

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It is when you convert it to Guided with Viper or similar (UT146). And, no, this doesn't particularly make much sense, as it's meant to be just adding a sensor suite and control surfaces to a normal bullet, rather than turning it into a gyroc.
Huh. So it does. That means that if you take a gauss minineedler and put viper needles (requires TL12) in it, they'll still do 1d(3) pi- damage, but move at all of 50 yards/s.
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Old 11-13-2019, 10:29 AM   #24
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Default Re: 25mm Payload Rifle [Ultratech]

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It is when you convert it to Guided with Viper or similar (UT146). And, no, this doesn't particularly make much sense, as it's meant to be just adding a sensor suite and control surfaces to a normal bullet, rather than turning it into a gyroc.



At TL 9, Viper and APEP shouldn't be combinable for calibers below 30mm. Viper has a minimum caliber of 15mm at TL 9, while an APEP's actual projectile (after discarding the sabot) would be - based on the APDSDU round from HT it's replacing - around 50% of the weapon's nominal caliber. Granted, UT doesn't explicitly disallow this combination, but it makes sense. UT's APDS/APEP entries do imply a 75% caliber projectile (pi class doesn't drop - that is, caliber doesn't go down below 15mm - unless below 20mm), but I feel HT's stats are more realistic. Indeed, integrating UT and HT ammunition options would be a good idea, which would change APEP to be x1.5 damage and AD (2) (rather than AD (3)). It also would introduce fin-stabilized versions of APDS and APEP, for further increased range and damage.

And yeah, the gyroc is, sadly, a fairly pitiful weapon. Granted, rifles wouldn't be that great if you had all your weapons designed to be loaded with 9mm Parabellum. "Hot" gyrocs would make some sense, with higher damage due to a higher sustained velocity, and possibly longer range if they are longer (and thus hold more propellant). This might allow gyrocs to more be competitive with conventional rifles, particularly if you adjust ETC down to a less-problematic x1.2 or x1.3 damage (+1/die) and range, reserving x1.5 for TL10's ETK.

The fact gyroc projectiles need a special modification to become capable of getting the Viper/etc treatment, but bullets can get converted no problem, is also a bit problematic. Bullets should also be at least x10 to base cost, and arguably more (gyrocs already have most of the control surfaces to keep themselves stable in flight, so should need less modification than bullets, which will need those added and will need to deal with spin), before they can get a sensor suite installed.
I would like to see more discussion leading to constructive guidelines about several of the issues with UT ammo. Fast small bullets don't have a lot of space for control surfaces and most of those will not be very effective. The time to target shouldn't change which puts a crimp in how much the bullet can be made to deviate and home on the target. and changing the time to target would drastically change the delivered force for non-payload munitions. Also some sensor sensibility and pitting sensors against Powers.
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Old 11-13-2019, 10:43 AM   #25
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by Joseph Paul View Post
I would like to see more discussion leading to constructive guidelines about several of the issues with UT ammo. Fast small bullets don't have a lot of space for control surfaces and most of those will not be very effective. The time to target shouldn't change which puts a crimp in how much the bullet can be made to deviate and home on the target. and changing the time to target would drastically change the delivered force for non-payload munitions. Also some sensor sensibility and pitting sensors against Powers.
High Tech gives the coarse rule of thumb of using 500 yards/sec for low angle shot times and 250 yards/sec for high angle shots. You could use those numbers for per round speed of viper rounds.
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Old 11-13-2019, 02:12 PM   #26
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by ericthered View Post
Those are machine guns, and they lighter of the two weighs over 90 lbs. I'd hesitate to call either "low-powered cannon" or to use them as a useful basline for the range of a projectile launched from a 1.5 lb weapons system.
You might hesitate, but it's absolutely correct for the MG 151/20. The M242 seems like a stretch with 1100 m/s muzzle velocity.

However, you're quite right that 'low-powered cannon' does still mean a lot higher velocity than you'd expect to get from a short underbarrel device.
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Old 11-13-2019, 04:54 PM   #27
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by Ulzgoroth View Post
You might hesitate, but it's absolutely correct for the MG 151/20. The M242 seems like a stretch with 1100 m/s muzzle velocity.

However, you're quite right that 'low-powered cannon' does still mean a lot higher velocity than you'd expect to get from a short underbarrel device.
The round for the M242 is 25x223mm and is in a necked down cartridge. The OICW program has 25x53mm cartridges for <edit> so called "high velocity" work</end edit>. Not exactly the same rodeo...
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Old 11-14-2019, 10:28 PM   #28
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Default Re: 25mm Payload Rifle [Ultratech]

IIRC one of the advantages of the 25mm weapon (Apart from longer range and more flatter trajectory due to higher velocity than 40mm) is that collateral damage can be less as well (which might be desirable under certain ROE.. alot of time and effort is devised into making weapons that limit collateral damage without sacrificing lethality. Whether its tungsten micro shrapnel warheads or kinetic ginsu hellfire missiles. Alot of the weapon's utility (IRL at least) is determined by role/purpose and politics.
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Old 11-14-2019, 11:17 PM   #29
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Default Re: 25mm Payload Rifle [Ultratech]

True, though I think that biochemical aerosol (sleep), shapecharge and tangler will be the default applications though. With a 2 yard radius, sleep rounds would incapacitate targets nearly as fast as tangler rounds, and would potentially incapacitate multiple people.
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Old 11-15-2019, 08:28 AM   #30
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Default Re: 25mm Payload Rifle [Ultratech]

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Originally Posted by ericthered View Post
Those are machine guns, and they lighter of the two weighs over 90 lbs. I'd hesitate to call either "low-powered cannon" or to use them as a useful basline for the range of a projectile launched from a 1.5 lb weapons system.
Okay. Try the AGS-17, with a 30x29mm grenade. It has a maximum range of 1700m. The 20x28mm grenade from the OICW project having a maximum range is perfectly within reason looking at that, and therefore so is the UT 25mm grenade. If it were fired from a lightweight launcher a case could be made for it having higher recoil than Rcl 3, but it's an underslung weapon so the total weapon system's weight is going to be 3.5+ pounds, and Rcl 3 seems reasonable (that the rules say you can mount it on a heavy pistol possibly not so much).
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