No, if your going to do it via the RPG-7 method, you would want the tube to be totally hollow (for 3rd person anyways) but like I said, it really isn't worth it here to do so and your better off just not having any tube and the cap staying on after firing, like pretty all the AT and AA weapons we have (with the exception of the RPG-7 and the blowpipe), so then you can have a nice and simple LOD setup that always works properly.
If you look at the RPG-7s geom1 LOD2, which is the "3rd person Been Fired LOD" where there is no projectile, you will see it is hollow:
The 1p LOD2 isn't however since the player never looks down it to see:
Then the 3p LOD0, LOD1, LOD3 & LOD4 are the actual "non-fired" lods (note LOD2 is skipped), but these only work properly before the weapon has fired, and normally bug out even after the weapon has been fired and reloaded, forcing players to draw LOD0 even at extreme view distance.
Now this is only worth doing in the case of the RPG-7 since the warhead is so damn obvious, both in 1p and 3p, that if it wasn't removed it would look really, really bad, and unfortunately having to break the LODs, and having no "been fired" LODs either, is the only way to do it well in BF2.
If you look at pretty much all our AT weapons, like the Predator, their big caps stay on even after firing since they just have normal LOD setups and it simply isn't worth breaking the LODs for.
So again for this weapon, I would really not recommend going down this route of having the cap removed and exposing an empty tube after launching, as it is such a small detail it is not worth breaking the LOD system for or the extra mesh memory and work to have it happen, let alone all the extra tris and texture space required too. Just keep this thing simple and only model the exterior with the cap permanently welded to the front of the launcher.