XM25 Counter Defilade Target Engagement System

[The_Ryujin]

Originally Posted by TheOneRonin

I've checked out the XM29, but I'm not sure how to scale up the damage for moving from 20mm grenades...

I guess I'm having a hard time determining what fits in-between those existing rounds.

Thoughts?

Assuming the warhead in the 25mm version is roughly just a scaled up version of the 20mm version that works out to a near doubling of volume and weight. In 4th ed explosive damage scales with the square root of the explosives weight (though in fact it should be the cube root... but that's another can o' worms) so that means that the 25mm warhead should do around ~140% more damage or 2d-1 or so.

Fragmation damage should also go up by the same amount (not sure if that's raw but it does make sense) giving ~[1d+2].

So all in all 2d-1 cr ex [1d+2].

[Fred Brackin]

Originally Posted by The_Ryujin

Assuming the warhead in the 25mm version is roughly just a scaled up version of the 20mm version that works out to a near doubling of volume and weight. .

There are non scaling components that can't be handwaved at this size. Mostly the fuse and detonator. You could scale the total interior volume the way you did but you'd subtract a fixed amount for the fuse mechanism and end up with a proportionately larger interior volume for the 25mm.

Compare the cr ex follow up damage fro the 20mm and 25mm autocannon rounds in HT if you don't want to look at grenades. Those are approximately double and not just +40%.

I see that the MD 307 was to use a 25 x 59mm round and the newer weapon in question used a 25 x 40mm. I strongly suspect that this is just the same warhead in a shorter case to reduce weight and recoil at he expense of range.

Really, you have the cr ex and frag of _a_ 25mm launcher grenade. I wouldn't expect those stats to be that different for a slightly different launcher grenade.

[gruundehn]

Just a note to everyone: In US military designations the starting "X" means prototype and is removed once the model is in production. Thus the item would be the M-29 not the XM-29. Just one of the points I'm a stickler about.

[Tomsdad]

Originally Posted by TheOneRonin

I've checked out the XM29, but I'm not sure how to scale up the damage for moving from 20mm grenades to 25mm grenades.

There is a HUGE jump between the 20mm XM29 and 40mm M203 grenades:

1d+1 [1d] cr ex (20mm) vs. 4d-1 [2d] cr ex (40mm).

Also, the GD M307 that Fred mentioned fires a 25mm grenade, but it's grenades do 4d+2(10) cr ex / 3d-1[1d+1] cr ex, which is a more powerful explosion than the 40mm grenades, which just seems wrong to me.

I guess I'm having a hard time determining what fits in-between those existing rounds.

Thoughts?

The GD M307 is 25mm (pg144) I'd start with that. But sorry yes as stated you have to compare like for like in warhead.

The M29 is 20x28mm and the M307 is firing 25x59mm, and the XM25 is firing 25x40mm (but the M307 seems to have more range but that may not be relevant here).

[Tomsdad]

Originally Posted by gruundehn

Just a note to everyone: In US military designations the starting "X" means prototype and is removed once the model is in production. Thus the item would be the M-29 not the XM-29. Just one of the points I'm a stickler about.

I figured that what it meant, but did the (X)M29 every actually get into active service*?

I seem to remember seeing it first in some "Tom Clancy: super elite solider", game. Back when the PS3 was new


* I thought I heard that the weight of the whole thing, plus the weight of two sets of ammunition made it a non starter in general combat.

[Phantasm]

Originally Posted by Tomsdad

I figured that what it meant, but did the (X)M29 every actually get into active service*?

According to Wikipedia, it was cancelled for the reasons you stated.

[Tomsdad]

Originally Posted by tbrock1031

According to Wikipedia, it was cancelled for the reasons you stated.

Aha, right

cheers

TD

[Ulzgoroth]

Originally Posted by Tomsdad

The GD M307 is 25mm (pg144) I'd start with that. But sorry yes as stated you have to compare like for like in warhead.

The M29 is 20x28mm and the M307 is firing 25x59mm, and the XM25 is firing 25x40mm (but the M307 seems to have more range but that may not be relevant here).

From this Wikipedia article the difference is indeed just a matter of a higher-velocity round for the heavier weapons.

[ronom]

I think Barrett is working on the XM109, which can be converted from .50BMG to the higher velocity 25MM grenades.

[Tomsdad]

Originally Posted by Ulzgoroth

From this Wikipedia article the difference is indeed just a matter of a higher-velocity round for the heavier weapons.

Right that makes sense (I assumed it was going to be that, but its not my area of expertise, so I didn't want to definitively say that's what it was), ok then pretty simple. Use the 25mm x 60mm stats for damage and effect, and the reduced range from the wiki for the 25x39mm fired from the XM25.


Cheers
TD