The HSTV-L and RDF/LT Guns being renamed to the 75mm ADMAG isn’t necessarily a bad thing or incorrect. From what I can find in other documents not listed in that report, the XM274 was only mounted on the MC-LAV prototype, and a slim chance of it being mounted on a later version of the RDF/LT with a remote controlled Turret.
However, I do agree that there are performance issues with the current implementation of the APFSDS ammo for the gun in game.
The information here is from Documents dated June 1978, and October 1975, which means this data is from well before the XM274 even entered prototyping phase in the 1984/85 time frame. But, well within the 75mm ADMAG testing time frame.
Keep in mind certain values are under the assumption that for example, the penetrator length runs from approximately the back of the nose cone to near the end of the fin assembly as none of these rounds are listed as having tracers. Also keep in mind that the Flight diameter would be different from the penetrator mean diameter for L-O as the flight diameter would also include Buttress thread diameter. Or in some cases nose cone diameter, and does not account for the variable diameter of the actual penetrator.
Note that the DARPA Memo also mentions performance similar to the 105mm rounds in development at the time. The AAI Penetrator shows similar performance to the initial XM735 Prototype from 1973/74. The memo also mentions a 105mm round with a muzzle velocity of 4820ft/s or 1469m/s, given the time period and velocity, this would most likely be XM735E1.
Figure 6/A, The AAI Penetrator, most likely to be the aforementioned projectile with 2lb penetrator going by the listed in flight mass. Which means it should have a Muzzle Velocity of 5450ft/s or 1661m/s according to the DARPA Memo.
AAI Projectile Details
| Property |
Calibers |
inches |
mm |
| Projectile Length |
15.38 |
12.47 |
316.7 |
| Projectile Ø Flight |
1.0 |
.811 |
20.6 |
| ~Penetrator Length~ |
12.78 |
10.364 |
263.26 |
| Fin Assembly Diameter |
2.61 |
2.1167 |
53.76 |
| Fin Assembly Length |
2.46 |
1.995 |
50.67 |
| Nose Cone Length |
2.6 |
2.108 |
53.54 |
| Mass Properties |
lbs. |
kg |
| Mass as Fired |
|
|
| Mass in Flight |
3.04 |
1.38 |
| Mass of Penetrator |
2.0 |
.907 |
| Penetrator L-O |
mm |
| Length Total |
260 |
| Ø Mean |
15.45 |
| Length Frustum |
0 |
| Ø Frustum Tip End |
0 |
| Property |
Penetrator |
Target |
| Material |
DU Staballoy |
Steel |
| Mat Type |
U-0.75%Ti |
RHA |
| Density |
18,600kg/m3 |
7,850kg/m3 |
| RHA BHN |
|
260 |
| Velocity Decay |
ft/s |
m/s |
| 1st km |
292 |
89 |
| Per extra km |
289 |
88 |
| Velocity @ Rng |
ft/s |
m/s |
| Muzzle |
5450 |
1661 |
| 100m |
5420 |
1652 |
| 500m |
5302 |
1616 |
| 1000m |
5158 |
1572 |
| 1500m |
5013 |
1528 |
| 2000m |
4869 |
1484 |
| Pen @ Rng (mm) |
Vert |
30° |
60° |
| Muzzle |
265 |
237 |
155 |
| 100m |
264 |
236 |
154 |
| 500m |
260 |
233 |
152 |
| 1000m |
255 |
228 |
149 |
| 1500m |
249 |
223 |
145 |
| 2000m |
243 |
217 |
142 |
Figures 3 and 4 for AAAC-II are listed in ADA058596 as that of a previous design, again given the time period, that would likely make it the first iteration of the 3lb penetrator design mentioned in the DARPA memo with a muzzle velocity of 5250ft/s or 1600m/s. The in flight mass listed in both ADA diagrams seems to back this up. The projectile flight diameter listed for these variants is also explained as being that of the Nose Cone/Windshield, which is larger than the main body diameter.
AAAC-II Projectile Datails
| Property |
Calibers |
inches |
mm |
| Projectile Length |
18.34 |
16.689 |
423.9 |
| Projectile Ø Flight |
1.0 |
0.91 |
23.114 |
| ~Penetrator Length~ |
15.61 |
14.205 |
360.81 |
| Fin Assembly Diameter |
2.418 |
2.2 |
55.88 |
| Fin Assembly Length |
4.12 |
3.749 |
95.229 |
| Nose Cone Length |
2.73 |
2.484 |
63.101 |
| Mass Properties |
lbs. |
kg |
| Mass as Fired |
|
|
| Mass in Flight |
4.19 |
1.9 |
| Mass of Penetrator |
3.00 |
1.36 |
| Penetrator L-O |
mm |
| Length Total |
360 |
| Ø Mean |
16.08 |
| Length Frustum |
0 |
| Ø Frustum Tip End |
0 |
| Property |
Penetrator |
Target |
| Material |
DU Staballoy |
Steel |
| Mat Type |
U-0.75%Ti |
RHA |
| Density |
18,600kg/m3 |
7,850kg/m3 |
| RHA BHN |
|
260 |
| Velocity Decay |
ft/s |
m/s |
| 1st km |
280 |
85 |
| Per extra km |
276 |
84 |
| Velocity @ Rng |
ft/s |
m/s |
| Muzzle |
5250 |
1600 |
| 100m |
5222 |
1592 |
| 500m |
5110 |
1557 |
| 1000m |
4970 |
1515 |
| 1500m |
4832 |
1473 |
| 2000m |
4694 |
1431 |
| Pen @ Rng (mm) |
Vert |
30° |
60° |
| Muzzle |
335 |
300 |
196 |
| 100m |
334 |
299 |
195 |
| 500m |
328 |
294 |
192 |
| 1000m |
321 |
287 |
187 |
| 1500m |
313 |
280 |
183 |
| 2000m |
305 |
273 |
178 |
More to be added later…
3 Likes
I stick with my previous statement had the HSTV-L or RDF-LT turned into a production tank it would have received the XM274. But during teating IDK I don’t have one sitting next to me so it’s all speculation from me.
gotta love how two got denied for nonsensical reasons
“It’s not a bug. All similar vehicles have similar DM. In case of the Pantsir it’s an actual armor that protects ammo.” literally saying we dont care, this russian thing has it so HSTVL has to
and another denied based on an iffy bug report saying that the gun designation was wrong even though it seems to be that the gun was redesignated to XM247 with no changes, so its just an excuse to not buff it
and im guessing AAAC-III which is delta 3 has the pen of m774
i hope they atleast add delta 2 tbh
