Small Arms Ammunition

[Daryk]

I found this on YouTube: https://www.youtube.com/watch?v=BoBOuv6qJNU

Given that the bog standard Auto-Rifle uses ammunition that weighs around what standard 5.56 does now (about half a kilo for 30 rounds), it seems completely reasonable that "modern" ammo would be more powerful than current 5.56.  The polymer casings used in the video are about 30% lighter AND achieve a higher muzzle velocity with a larger bullet (6.8 mm vice 5.56).  If you put that weight savings into MORE power you can easily explain the improvement from the "Vintage Auto-Rifle" damage of 2 AP/3 BD to the current Auto-Rifle's 4/4.  And the improved heat management helps explain the increased burst rate (from 10 to 15) too.

[Daemion]

Nice find.
Since we're on small arms ammo, I have a couple questions which I'm only expecting guesses for:

- Refresher: It takes a 15-round burst for a 4/4 weapon to get up above the .5 damage needed to round up to a full BT point, right?
- How much does the bullet weigh?  I'm assuming equivalent to the 5.56 NATO.
- Does anyone know roughly what the GAU-8's projectiles weigh, once free of the casing and powder (, and sabot if it uses 'em)?

I know where I'm trying to go with this.  I'm hoping some of you can pick up on it.

I'm wanting to discuss the merits of penetration power.  What some people fail to realize is that mass has something to do with it.  I'm trying to figure out a baseline where, currently, the GAU-8 is considered a viable anti-tank/armor weapon, but most small-arms are not.

[CVB]

GAU-8
Armor Piercing Incendiary (API): projectile weight 395 g
High Explosive Incendiary (HEI): projectile weight 378 g

Edit:
The PGU-14/B API  projectile consists of a lightweight aluminum body, cast around a smaller caliber depleted uranium penetrating core, so no sabot.
Additional info for API:
v₀ = 1,000 m/s
Muzzle energy = 200 kJ

[Daryk]

A 15 round burst does in fact get a 4/4 weapon over the 0.5 threshold.

I would expect the bullet to weigh more.  A 5.56 bullet weighs 4 to 4.1 grams.  The 6.8 bullet is probably around 5 grams, maybe 6.

GAU-8 AP rounds weigh about 400 grams (they use depleted Uranium alloy).  There's really no comparison to small arms ammo with them.

[Daemion]

Thanks, guys.  That really helps.

[DevianID]

So imho the battletech autorifle probably uses caseless high explosive low velocity ammo in the 9/10 mm range.  It has a lot (a lot) of stopping power but as a low velocity caseless round you can also rapid fire them and won't break your arm shooting them.  Caseless because the autorifle is tech C so they ironed out the kinks in the 3mm real world caseless we tried but couldn't perfect.

[Daryk]

It certainly could use caseless ammo, but I think TPTB were deliberately vague on that point.

[SlightlyIrritatedCat]

Plus you have in universe sources that specifically point out that some small arms are caseless but not others, and in other parts of the fiction you have weapons leaving expended cases.  Just like IRL nothing says that every small arm in the Sphere will be using the same ammunition.  They're probably a mix of various cased and caseless technologies depending on the manufacturer and the intended role of the small arm.

And given that their armor technology has shifted toward ablative or semi-ablative materials, as well as the shorter engagement ranges.  This could well indicate they prioritize rate of fire over projectile velocity because it's more important for them to be able to lay down a dozen or two rounds into a small group instead of one to three rounds with much higher velocity and energy.

[CVB]

Do we have any canon sources on the legality of explosive small arms ammo in BT universe international warfare? There have been attempts of limitations as least as far back as the 1868 St. Petersburg declarations, and the reasons weren't entirely humanitarian only (not going any deeper because of forum rules).

[Daemion]

While it's interesting to try to wrap your head around, even Sarna points out the inconsistencies of the abstract Infantry rules for the standard scale game.

And, mass does seem to play some part in it. While people complain about slow impacts doing damage, I'd like to point out that a Wasp's punch which does two armor/internal damage weighs in probably around 2 tons, more or less. (That value is derived for the replacement cost for a location's internal structure out of ye olde BMR Repairs and Replacements rules.  I'd also like to point out that replacement myomer is based on engine rating on top of that.) 

Funny how that lines up with how the damage is calculated.

But, to look at the math, that's 2,000 kg.  Or, 2,000,000 grams.  Compared to 400 or 6 grams.

And, we haven't added velocity into the mix yet, but it really should be a factor. I'm not going to go into it, but there it is.

It is nice to see improvements in modern day.  I'm wondering, though, if armor defeating rounds for small arms might actuall include some heavy metal in their projectiles, along with, maybe, some microchipped homing and self propulsion.
 

[DOC_Agren]

It certainly could use caseless ammo, but I think TPTB were deliberately vague on that point.

which I don't mind...
some weapons using caseless, other spray cases everywhere it was the future of the 80's

[idea weenie]

While it's interesting to try to wrap your head around, even Sarna points out the inconsistencies of the abstract Infantry rules for the standard scale game.

And, mass does seem to play some part in it. While people complain about slow impacts doing damage, I'd like to point out that a Wasp's punch which does two armor/internal damage weighs in probably around 2 tons, more or less. (That value is derived for the replacement cost for a location's internal structure out of ye olde BMR Repairs and Replacements rules.  I'd also like to point out that replacement myomer is based on engine rating on top of that.) 

Funny how that lines up with how the damage is calculated.

But, to look at the math, that's 2,000 kg.  Or, 2,000,000 grams.  Compared to 400 or 6 grams.

And, we haven't added velocity into the mix yet, but it really should be a factor. I'm not going to go into it, but there it is.

It is nice to see improvements in modern day.  I'm wondering, though, if armor defeating rounds for small arms might actuall include some heavy metal in their projectiles, along with, maybe, some microchipped homing and self propulsion.
 

One thing I tend to use as a yardstick, is the SRM.  It is 10 kg, delivers 2 pts of BT damage, at a range of 9 hexes.  Simplifying, that is 5 kg for 1 pt of BT damage at 9 hexes.

Balance the other anti-Mech weapons with respect to that, and you have some nice flexibility.

Want more range?  You can't reduce the damage so you have to raise the mass
Want more damage?  Either lower the range or raise the mass.
Want less mass?  Lower the range (damage is already at the minimum)

So if you want something massing a total of 800 grams (projectile weight ~400 grams) to do 1 pt of damage at 9 hexes, then you will need 6-7 of them.  If you want something massing 12 grams (with a 6 gram projectile) to do 1 pt of damage at 9 hexes, then you will need ~400 of them

[RifleMech]

I found this on YouTube: https://www.youtube.com/watch?v=BoBOuv6qJNU

Given that the bog standard Auto-Rifle uses ammunition that weighs around what standard 5.56 does now (about half a kilo for 30 rounds), it seems completely reasonable that "modern" ammo would be more powerful than current 5.56.  The polymer casings used in the video are about 30% lighter AND achieve a higher muzzle velocity with a larger bullet (6.8 mm vice 5.56).  If you put that weight savings into MORE power you can easily explain the improvement from the "Vintage Auto-Rifle" damage of 2 AP/3 BD to the current Auto-Rifle's 4/4.  And the improved heat management helps explain the increased burst rate (from 10 to 15) too.

Very cool but I know I missed somethings. How does the 6.8 plastic round compare to a brass one the same size? How much of the improvement is the larger round and how much the casing when compared to the 5.56? And what's the difference between the Civilian and Military versions?

Also at one point the M240 7.62mm machine gun was quickly refitted to fire the plastic 6.8mm round. How do the two rounds compare? Besides the 6.8mm plastic being lighter so more rounds can be carried. Also would the M240 still be a vintage machine gun with the new barrel and ammo or a new weapon? How do we handle it in came terms?  Quirks?  An easy ammo conversion quirk? Takes x turns to complete? And a complicated conversion quirk must send back to the shop to be done?

Also, how do we handle replica firearms that are manufactured to more modern standards? And from what I read rounds are made to be fired by older weapons. Will that remain true in the future?

[Daryk]

For starters, it's 30% lighter overall compared to the 5.56 cartridge.  It also has a higher muzzle velocity.  With a an extra gram or two of bullet and the higher muzzle velocity, that's a LOT more damage down range.  There was also a mention of some kind of geometry change internal to the cartridge.  Advances in fluid dynamics also impact ballistics... 

[Nicoli]

It is nice to see improvements in modern day.  I'm wondering, though, if armor defeating rounds for small arms might actuall include some heavy metal in their projectiles, along with, maybe, some microchipped homing and self propulsion.
 

Doesn't matter if they do, Armor weakens after each successive hit regardless if it penetrates or not. This is why things like motorcycle helmets should be checked after a drop from a good height. Armor designed to handle stronger impacts either need to be incredibly thick and heavy to resist that weakening, or use self destruction to handle it. Battletech armor is handled very much of the self-sacrificing variety which means it can be degraded by multiple small hits.

[RifleMech]

For starters, it's 30% lighter overall compared to the 5.56 cartridge.  It also has a higher muzzle velocity.  With a an extra gram or two of bullet and the higher muzzle velocity, that's a LOT more damage down range.  There was also a mention of some kind of geometry change internal to the cartridge.  Advances in fluid dynamics also impact ballistics... 

Which means what exactly, beyond the 30% increase in ammo? I think he said the range was increased but the accuracy fell off because of the moving barrel. If I remember right wouldn't they cancel each other out?  I'm also going to guess that there's an increased AP/BD. But would it be +1 to each or +2 to one or the other? Also what about when the barrel gets swapped with the ammo? Would everything be improved?
What about when the ammo gets smaller? Number of rounds goes up the rest stays the same?

[Daryk]

If you invest the 30% weight savings in more bullet and/or propellant, you get more damage down range.  The point I was making was that 4/4 Auto-Rifle ammo weighs the SAME as 5.56 (30 rounds for half a kilo), so if the individual cartridges don't waste mass on brass, it seems obvious that's where the extra 2 AP and 1 BD come from.

And as far as what the guy in the video said, he pointed out that a moving barrel tends to reduce accuracy, but he used that fact to transition to talking about the ammo as a way to overcome that problem (i.e., higher muzzle velocity).

[RifleMech]

If you invest the 30% weight savings in more bullet and/or propellant, you get more damage down range.  The point I was making was that 4/4 Auto-Rifle ammo weighs the SAME as 5.56 (30 rounds for half a kilo), so if the individual cartridges don't waste mass on brass, it seems obvious that's where the extra 2 AP and 1 BD come from.

And as far as what the guy in the video said, he pointed out that a moving barrel tends to reduce accuracy, but he used that fact to transition to talking about the ammo as a way to overcome that problem (i.e., higher muzzle velocity).

The thing is that weapon wasn't firing a 5.56. It was firing a 6.8. If the 6.8 is the Auto-Rifle wouldn't the increased;
AP come from the bigger round fired?
BD come from the auto-rifle's increased rate of fire?
power go to longer range?

What happens when the M270 is refitted from 7.62 to 6.8? Same everything but more ammo?

What happens to the Vintage Auto-Rifle firing a plastic 5.56 round? Will it blow up, have an increase in range, AP and BD, or just have 30% more rounds for the weight?

I've also read that rounds are made to be backwards compatible with older guns. I don't think that would change in the future. I can see new rounds made for new guns but you'd still want to be able to retrofit some weapons at least. Like what they did with the M270.

Let's say they made plastic rounds in .38 caliber. Would the Vintage Revolver blow up, or would the round be made to work with the gun? If made to work with the gun, would everything stay the same, except ammo weight, or would there be any increases in performance?

[Daryk]

The only M270 I'm seeing is the Multiple Launch Rocket System (MLRS).  Do you mean the M240 machine gun?  That was actually featured in the video (and yes, it only took a barrel change to enable firing the plastic cased ammo; in that specific case, it would mean more ammo (a LOT more), and enable longer bursts through reduced heat transferred to the block).

To be clear, I'm NOT saying the Auto-Rifle is 6.8mm.  I'm saying this particular technology leap could easily explain how you get to the Auto-Rifle (4/4) from the "Vintage" Auto-Rifle (2/3).

And as far as the mechanics, AP and BD are separate from the burst rate.  Single shots have the same AP and BD as bursts, and bursts simply increase the damage a particular weapon does at the TW scale (AToW Companion page 171 for that; the mechanic is different at AToW scale: AToW page 179 refers).

[RifleMech]

The only M270 I'm seeing is the Multiple Launch Rocket System (MLRS).  Do you mean the M240 machine gun?  That was actually featured in the video (and yes, it only took a barrel change to enable firing the plastic cased ammo; in that specific case, it would mean more ammo (a LOT more), and enable longer bursts through reduced heat transferred to the block).

Yeah. The M240. Sorry. Don't know where the 7 came from. So with the new barrel and ammo, the BD would go up from increased rate of fire. What about the AP and range? Would they go down or would the increased power compensate to keep them the same?

To be clear, I'm NOT saying the Auto-Rifle is 6.8mm.  I'm saying this particular technology leap could easily explain how you get to the Auto-Rifle (4/4) from the "Vintage" Auto-Rifle (2/3).

I didn't say you did and I can see how weapons get more powerful. But doesn't some of that depend on the ammo?
 

And as far as the mechanics, AP and BD are separate from the burst rate.  Single shots have the same AP and BD as bursts, and bursts simply increase the damage a particular weapon does at the TW scale (AToW Companion page 171 for that; the mechanic is different at AToW scale: AToW page 179 refers).

That's always confused me. In part because I have a hard time with AToW. If I fire a full burst from an Auto-Rifle at a tank, How many rounds hit and what's the damage? And in TW, does the Auto-Rifle have 30 shots doing .52 damage each or does it have 2 bursts doing .52 damage each? Why not just list the weight and damage of ammo fired per turn? Does a 6 shot Revolver fire all 6 shots for .17, or is that 6 .17 shots? I largely end up ignoring it or using bursts but it's still annoying.

[Daryk]

BD doesn't go up from increased rate of fire, TW scale damage does.  They are two different things.

Damage down range absolutely depends on ammo, but if you increase the propellant, you may need a heavier barrel, block, etc.  This particular technology advance gets around that.

If you fire a burst weapon at a tank at TW scale, the number of rounds that hit is irrelevant.  The burst rating is subsumed into the conversion formula.  The Auto-Rifle at TW scale has two bursts of 15 in a 30 round magazine (which can be made into a 45 round magazine with the Companion customization rules very easily, and for not that many C-Bills... hence my AR+ thread).  To answer your explicit question, it's two bursts that do 0.52 damage each.  Listing the weight of ammo and damage for each weapon would require more columns in the table that really aren't necessary.

In the case of the Revolver specifically, it's damage is reduced by the Reload Factor.  A Revolver only has 6 shots, so it's damage is 60% of what a 4/4 weapon with 10 shots would be.  No, I don't think Reload Factor is quite right, but that's a FAR different complaint, and one I partially addressed with my AR+ and "Adjusting Reload Factor" threads linked in my sig block.

[RifleMech]

BD doesn't go up from increased rate of fire, TW scale damage does.  They are two different things.

Which is confusing. If I fire a burst at a mech in AToW? Why wouldn't more rounds do more damage? and if not why does it in TW?

Damage down range absolutely depends on ammo, but if you increase the propellant, you may need a heavier barrel, block, etc.  This particular technology advance gets around that.

This is where I missed something. If a 5.56 rifle fires plastic rounds instead of brass, what happens? Same range and damage? More?
What if plastic rounds and brass rounds were mixed?

If you fire a burst weapon at a tank at TW scale, the number of rounds that hit is irrelevant.  The burst rating is subsumed into the conversion formula.  The Auto-Rifle at TW scale has two bursts of 15 in a 30 round magazine (which can be made into a 45 round magazine with the Companion customization rules very easily, and for not that many C-Bills... hence my AR+ thread).  To answer your explicit question, it's two bursts that do 0.52 damage each.  Listing the weight of ammo and damage for each weapon would require more columns in the table that really aren't necessary.

If firearms in TW only fire bursts, why list individual shots? Just like how many bursts and what that ammo weights. (Auto-Rifle 2 .48kg)

In the case of the Revolver specifically, it's damage is reduced by the Reload Factor.  A Revolver only has 6 shots, so it's damage is 60% of what a 4/4 weapon with 10 shots would be.  No, I don't think Reload Factor is quite right, but that's a FAR different complaint, and one I partially addressed with my AR+ and "Adjusting Reload Factor" threads linked in my sig block.

Is that a 6 round burst or 6 individual shots?

[Daryk]

It appears you didn't read the AToW page 179 reference.  The mechanic in AToW is that damage (not the BD of the weapon) goes up by 1 point per Margin of Success, up to a maximum of the number of rounds fired.  In contrast, the Companion conversion formula accounts for burst fire in the Damage Factor calculation.

If a 5.56 round that uses plastic instead of brass has the same amount of propellant and same weight bullet, it will do the same damage, but weigh 30% less.  If you mix plastic and brass rounds, you're probably violating every manufacturer warranty ever (and that assumes you don't have to change barrels to make it work).  As a game mechanic, I would just give you a bit less weight savings.

Many weapons only fire single shots.  The Companion formula is built to convert them all, whether single shot or burst of any size.

In the specific case of the Revolver, it's six individual shots.  Only weapons with a listed Burst rating fire bursts.

[RifleMech]

It appears you didn't read the AToW page 179 reference.  The mechanic in AToW is that damage (not the BD of the weapon) goes up by 1 point per Margin of Success, up to a maximum of the number of rounds fired.  In contrast, the Companion conversion formula accounts for burst fire in the Damage Factor calculation.

Read it. Don't always understand it. For example, the damage is based on the BD and it goes up depending on the Margin of Success. Standard damage goes up .25 damage per point of MoS. Burst goes up 1 point per MoS up to the max number of shots fired. So the BD does go up. Beyond that things get fuzzy. It doesn't apply to Vehicles does it?

If a 5.56 round that uses plastic instead of brass has the same amount of propellant and same weight bullet, it will do the same damage, but weigh 30% less.  If you mix plastic and brass rounds, you're probably violating every manufacturer warranty ever (and that assumes you don't have to change barrels to make it work).  As a game mechanic, I would just give you a bit less weight savings.

Okay but brass reduces the heat from the rounds fired. The video said that the rounds used the heat to be more powerful and the plastic stayed cool. So you'd either be stressing the weapon or the amount of propellant was reduced. I would hope the latter but maybe they make rounds for older gun and newer guns and read the package so you don't buy the wrong one. As for mixing? Probably but then just using the plastic probably would too. But if they function the same, other than heat, there shouldn't be a problem. Right?  As for game rules, I'd go with things stay the same but more ammo for the weight.

Many weapons only fire single shots.  The Companion formula is built to convert them all, whether single shot or burst of any size.

In the specific case of the Revolver, it's six individual shots.  Only weapons with a listed Burst rating fire bursts.

It seems written for single shot or full burst. I  don't doubt smaller bursts could be figured out but we're really going to need a spreadsheet for them.  AP/BD vs BAR and TW damage per shots fired.

So a Revolver fires 6 .17 damage shots. 1 shot per turn so it takes a full minute to empty the Revolver? And the Auto-Rifle is firing a .52 15 round burst every turn unless it fires a single shot for .17?

[Daryk]

I'm not sure what you mean by "applies to vehicles".  BD stays the same, but any individual shot can do more damage depending on the MoS.

The video is clear in stating that plastic is an insulator, which keeps the block cool when compared to brass which is a conductor.  It's the outside of the plastic that stayed cool.  Basically, more heat was transferred to the propellant, meaning higher muzzle velocity.  And yes, I said earlier you could choose to go with more ammo with the weight savings, or apply that weight savings to more power.  The latter would appear to be what the Auto-Rifle did, since the ammo weighs the same as 5.56.

I do use a spreadsheet to calculate burst damage, so varying burst size is no problem.  I've linked that particular sheet elsewhere, more than once.

You are correct about 6x0.17 shots, and that a full 15 round burst from an Auto-Rifle is 0.52 compared to its own single-shot damage of 0.17.

[RifleMech]

I'm not sure what you mean by "applies to vehicles".  BD stays the same, but any individual shot can do more damage depending on the MoS.

That answers one question. How about small support vehicles? They can mount the same weapons as infantry. Or larger vehicles and Mechs. Does their damage go up with the Mos?

The video is clear in stating that plastic is an insulator, which keeps the block cool when compared to brass which is a conductor.  It's the outside of the plastic that stayed cool.  Basically, more heat was transferred to the propellant, meaning higher muzzle velocity.  And yes, I said earlier you could choose to go with more ammo with the weight savings, or apply that weight savings to more power.  The latter would appear to be what the Auto-Rifle did, since the ammo weighs the same as 5.56.

I remember that part but I also remember that heat was bad and that the brass helped cool the gun. So if the plastic rounds didn't have reduced propellant, wouldn't the heat and increased power damage the gun? I suppose it could be okay for single shots from more modern guns but vintage guns? or bursts?

I'm not sure it's one or the other here. Just changing the casing made for a more powerful round. The heat burned propellant more efficiently or something. I didn't get that part. But it was the change in casing that made the rounds lighter. If the propellant is reduced too wouldn't the rounds be lighter still, meaning even more rounds for the same weight? And wouldn't the propellant have to be reduced or the weapon get overstressed and hot?

I do use a spreadsheet to calculate burst damage, so varying burst size is no problem.  I've linked that particular sheet elsewhere, more than once.

Cool! I must have missed that. Does it work with older excel programs? 

You are correct about 6x0.17 shots, and that a full 15 round burst from an Auto-Rifle is 0.52 compared to its own single-shot damage of 0.17.

   Cool! 

You do get what I was saying about how rounds can change the gun, right?  If modern rounds are made to work in older guns, which guns are vintage? And if a vintage weapon can be "upgraded" shouldn't that be reflected in the weapons stats?

[Daryk]

You use the AToW rules when you're playing AToW scale, and the TW scale rules when you're playing that.  It's determined by what you're playing, not the platform.  "Small support vehicles" exist in both.

Brass carries a small amount of heat with it when it's ejected, but conducts some to the block and rest of the weapon until it is.  Plastic carries more away when it's ejected because it's a much worse conductor of heat than brass.  Does that make sense?

The point the video was making was that 6.8mm rounds made with plastic casing were 30% lighter than 5.56mm ones with brass.  AND that those rounds had a heavier bullet and higher muzzle velocity.  Seriously, that's the mind blowing improvement we're seeing here at TL C in 2021.  That's why I linked the video here.

The spreadsheet should work with older versions.  The most advanced thing I used was conditional formatting.  Do you need a link to it, or have you seen it in the other conversations monbvol and I have had?

The point the video was making was that rounds engineered with backward compatibility in mind could result in weight savings for ammunition.  MY point was that if you took that technology and applied it to more power instead, you could achieve more power with the same weight.  I hope I'm making sense here...

[monbvol]

The caveat is that more power almost always means more pressure on the bolt, barrel, and possibly other inner workings that can significantly shorten a weapon's operational life.

For my sheet I'd recommend the one in my AU development thread right now though.  The one I have elsewhere I am pretty sure has a math error for ordinance support weapons.  If I remember I'll fix that when I get home.

[Daryk]

I'll confess to being a little lazy there... when I say "plastic", I really mean "composite".  The casings can handle the increased pressure and heat so the bolt and barrel don't have to.  The barrel just has to be big enough to pass the bullet.  It really is revolutionary technology application (since the tech has actually been around a while).

[RifleMech]

You use the AToW rules when you're playing AToW scale, and the TW scale rules when you're playing that.  It's determined by what you're playing, not the platform.  "Small support vehicles" exist in both.

However, one should be able to convert between the two. So what's the most damage an Auto-Rifle can do when mounted on a small vehicle and fired at a larger vehicle or Mech? Is it the same as when a trooper fires at the same target?

Brass carries a small amount of heat with it when it's ejected, but conducts some to the block and rest of the weapon until it is.  Plastic carries more away when it's ejected because it's a much worse conductor of heat than brass.  Does that make sense?

No. Sorry. It seems opposite of what was said about plastic.

The point the video was making was that 6.8mm rounds made with plastic casing were 30% lighter than 5.56mm ones with brass.  AND that those rounds had a heavier bullet and higher muzzle velocity.  Seriously, that's the mind blowing improvement we're seeing here at TL C in 2021.  That's why I linked the video here.

It is a big improvement and pretty cool. They do seem to have 5.56mm rounds though. Which makes me wonder what happens if you use them in a 5.56mm rifle made to shoot brass rounds. Do they intentionally have less propellant so not to stress the gun?

The spreadsheet should work with older versions.  The most advanced thing I used was conditional formatting.  Do you need a link to it, or have you seen it in the other conversations monbvol and I have had?

A link would be cool. Thanks 

The point the video was making was that rounds engineered with backward compatibility in mind could result in weight savings for ammunition.  MY point was that if you took that technology and applied it to more power instead, you could achieve more power with the same weight.  I hope I'm making sense here...

Okay. Backwards compatible. More ammo. The rest stays the same. Cool.  More power for same weight? Need a different gun. Which is what they did.

I'll confess to being a little lazy there... when I say "plastic", I really mean "composite".  The casings can handle the increased pressure and heat so the bolt and barrel don't have to.  The barrel just has to be big enough to pass the bullet.  It really is revolutionary technology application (since the tech has actually been around a while).

I'm pretty sure I saw in one of the videos that brass getting hot and removing heat when ejected was a good thing for the gun. Heat building up in the gun was bad for its parts and bad for ammo that was being loaded. The plastic composite rounds don't remove heat from the gun. That heat helps make the round more powerful.
For plastic to work in older guns the power would have to be reduced so as not to be so hot and cause problems for the gun. Along with being more power than the gun can handle. Right?

The caveat is that more power almost always means more pressure on the bolt, barrel, and possibly other inner workings that can significantly shorten a weapon's operational life.

For my sheet I'd recommend the one in my AU development thread right now though.  The one I have elsewhere I am pretty sure has a math error for ordinance support weapons.  If I remember I'll fix that when I get home.

That's what I thought.

Link please? With my luck I'll find the other one. Thanks