New weapons - XM5 and XM250

[Vespers War]

The Army is planning to replace the M4 carbine and M249 SAW for infantry, cavalry scouts, forward observers, and other soldiers who are considered likely to engage in close quarters combat. The new guns are supposed to start delivering in late 2023, and are the XM5 rifle and XM250 automatic rifle/light machine gun. They fire a new 6.8x51mm round, which has actual dimensions of 7.01x51.2mm. The XM5 is 4.44 kilograms when loaded with a 20-round box magazine and has a 33 centimeter barrel, while the XM250 takes a 100-round semi-rigid box to mass 8.97 kilograms with a 44.4 centimeter barrel and an integral bipod.

XM5 rifle
Wt 4.44, ROF 3, Mag 20, Dam 4, Pen 2-Nil, Bulk 6, SS 4, Burst 6, Rng 38

XM250 automatic rifle
Wt 8.97, ROF 5, Mag 100, Dam 4, Pen 2-3-Nil, Bulk 7, SS 3, Burst 7, Rng 48/62

Fire, Fusion & Steel wants these to have much longer barrels to handle the energy of the round. They end up with roughly the same range as the weapons they're replacing, but with slightly more damage from the XM5 and slightly better performance against armor from the XM250. Those are pretty much what the new weapons are intended for, giving better performance against opponents in modern armor, so I'm fairly pleased at how their stats came out in FF&S.

[Raellus]

Originally Posted by Vespers War

Fire, Fusion & Steel wants these to have much longer barrels to handle the energy of the round. They end up with roughly the same range as the weapons they're replacing, but with slightly more damage from the XM5 and slightly better performance against armor from the XM250. Those are pretty much what the new weapons are intended for, giving better performance against opponents in modern armor.

That's interesting. I thought that one of the major impetuses behind the 6.5-8mm movement was the poor performance of the 5.56mm round at the engagement distances common in Afghanistan. I think that over-specialization of weapons is a strategic mistake. Yeah, if you're doing a lot of CQB, a shorter barrel is very helpful, but if the engagement ranges increase for some tactical reason, now you're stuck with a sub-optimal weapon. No one can guarantee that Unit X is always going to be engaging targets at under 100m or whatever.

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[swaghauler]

Originally Posted by Vespers War

The Army is planning to replace the M4 carbine and M249 SAW for infantry, cavalry scouts, forward observers, and other soldiers who are considered likely to engage in close quarters combat. The new guns are supposed to start delivering in late 2023, and are the XM5 rifle and XM250 automatic rifle/light machine gun. They fire a new 6.8x51mm round, which has actual dimensions of 7.01x51.2mm. The XM5 is 4.44 kilograms when loaded with a 20-round box magazine and has a 33 centimeter barrel, while the XM250 takes a 100-round semi-rigid box to mass 8.97 kilograms with a 44.4 centimeter barrel and an integral bipod.

XM5 rifle
Wt 4.44, ROF 3, Mag 20, Dam 4, Pen 2-Nil, Bulk 6, SS 4, Burst 6, Rng 38

XM250 automatic rifle
Wt 8.97, ROF 5, Mag 100, Dam 4, Pen 2-3-Nil, Bulk 7, SS 3, Burst 7, Rng 48/62

Fire, Fusion & Steel wants these to have much longer barrels to handle the energy of the round. They end up with roughly the same range as the weapons they're replacing, but with slightly more damage from the XM5 and slightly better performance against armor from the XM250. Those are pretty much what the new weapons are intended for, giving better performance against opponents in modern armor, so I'm fairly pleased at how their stats came out in FF&S.

I'd say that the numbers are off. Sadly, this is common with FFS though. The XM5, using full-power ammo, is supposed to be accurate to between 700m and 800m with iron sights (I'm thinking that's optimistic); and a range in excess of 900m with the 1X to 8X variable magnification optic (I give it +16M to Short Range). That means that its "iron sight" range should be between 85m and 100m (75m is probably more realistic). The XM250 is supposed to have a range north of 1200m with an optic. That would be a Short Range of 150m.

[Vespers War]

My house rule for scopes is that they add 5% to range for each power of magnification, so the variable scope would add 5-40% based on setting. It also adds a bonus to hit at Medium or longer range equal to its magnification, but can't make that number better than the original score for the next lower range band. For example, someone with a combat asset in rifles of 12 would have to-hit rolls with Aimed Shots of 24/12/6/3. With a x8 scope, that would become 24/20/12/6 - Medium gets the full effect, while Long and Extreme get bumped up to the previous Medium and Long ratings.

I also rule that the maximum effect is equal to the shooter's skill with the weapon, so you'd need Small Arms (Rifle) 8 to take maximum effect of the scope.

With regards to range in FF&S, I think the issue is that barrels never become more efficient at producing range unless you change types entirely. The baseline barrel length in centimeters is the average muzzle energy in joules divided by the square of the bullet's diameter. The actual muzzle energy is based on the ratio of the actual barrel length to the baseline length, with a maximum of 2.3, and that's the primary determinant of range, with modifiers for stock type and a 10% boost for bolt-action rifles. A slow improvement of the rifling modifier for rifled barrels would allow for a modern barrel to be more effective than a Modele 1886 Lebel, which currently can't happen in the rules.

I'm also willing to wait and see how the rifles perform once the LRIP are delivered, since optimistic initial test results are not unheard of in small arms development.

[swaghauler]

Originally Posted by Vespers War

My house rule for scopes is that they add 5% to range for each power of magnification, so the variable scope would add 5-40% based on setting. It also adds a bonus to hit at Medium or longer range equal to its magnification, but can't make that number better than the original score for the next lower range band. For example, someone with a combat asset in rifles of 12 would have to-hit rolls with Aimed Shots of 24/12/6/3. With a x8 scope, that would become 24/20/12/6 - Medium gets the full effect, while Long and Extreme get bumped up to the previous Medium and Long ratings.

I also rule that the maximum effect is equal to the shooter's skill with the weapon, so you'd need Small Arms (Rifle) 8 to take maximum effect of the scope.

With regards to range in FF&S, I think the issue is that barrels never become more efficient at producing range unless you change types entirely. The baseline barrel length in centimeters is the average muzzle energy in joules divided by the square of the bullet's diameter. The actual muzzle energy is based on the ratio of the actual barrel length to the baseline length, with a maximum of 2.3, and that's the primary determinant of range, with modifiers for stock type and a 10% boost for bolt-action rifles. A slow improvement of the rifling modifier for rifled barrels would allow for a modern barrel to be more effective than a Modele 1886 Lebel, which currently can't happen in the rules.

I'm also willing to wait and see how the rifles perform once the LRIP are delivered, since optimistic initial test results are not unheard of in small arms development.

I'm having trouble believing the hype around the XM5 too. Anyways...So when are we (the forum) going to figure out a fix for the FFS formula? Between you, me, Paul, Teg, & Milano, somebody surely has an idea.

[pmulcahy11b]

Originally Posted by swaghauler

I'm having trouble believing the hype around the XM5 too. Anyways...So when are we (the forum) going to figure out a fix for the FFS formula? Between you, me, Paul, Teg, & Milano, somebody surely has an idea.

Well...what I do for stuff like the XM5 is to bump up the range and penetration to AP levels. One penetration band and x1.2 for range. I haven't been able to come up with a comprehensive fix...I suck at the kind of math-fu that would take.

[pmulcahy11b]

Originally Posted by Vespers War

A slow improvement of the rifling modifier for rifled barrels would allow for a modern barrel to be more effective than a Modele 1886 Lebel, which currently can't happen in the rules.

It can happen in FFS to an extent; design your older rifles at a lower tech level. Also, down-tech the ammo used.

[Vespers War]

Originally Posted by pmulcahy11b

It can happen in FFS to an extent; design your older rifles at a lower tech level. Also, down-tech the ammo used.

Yeah, I've done that a little for tank rounds - my current solution for APFSDS-T rounds as opposed to APFSDS-DU is to tech down the tungsten penetrator one TL for Pen only, with all the other stats (range, damage, etc) being at the appropriate TL.

I haven't tried playing around with it for small arms yet, and I'll probably only do it manually because the small arms spreadsheet I built is a lot more finicky than the artillery spreadsheet, with more variables that make it easier to break.

The other alternative I see is a variable to the rifling modifier for Rifled barrels based on TL. Smokeless powder is a very late TL 3 development (what World Tamer's Handbook would probably label TL 3M), so some sort of formula that gives the book's rifling modifier of 1 at TL 4 (year 1900) and slowly reduces it over time might work, maybe something like [1.2 - (TL*0.05)] so that at TL 9 (year 2000) the modifier is 0.75.