3 1/2 months is a good time? I've had Longshots in service for over a year now bro... fact is you broke it.
Yes 13mm foam is THE ONLY foam that fits aluminium and yes it will most likely increase ranges.
Weapons, in real life are able to be classified and judged using the following criteria (this is only one system of course)
Rate of Fire
Each of these is referred to in this system as a force multiplier. For example a rifle with a 6 shot clip is 6x more effective, or 6x more of a threat, in combat than a single shot one of the same type.
In nerf, accuracy depends on darts and lethality is not considered thus
Rate of fire
Are the important things when considering a blaster.
By singling a longshot you are reducing its rate of fire drastically, also decreasing its capacity by 6x (in the case of a standard clip) all to achieve a range that is easily achievable through a different blaster.
If singled longshots shot further than most other nerf guns their existence would be justified however the ranges they achieve are not up to par with many more simpler blasters and they're harder to prime and when singled an enormous amount of space is wasted in the casing.
Thus I feel it is fair to argue as a fact that singled longshots serve no useful function that cannot be performed better by a simpler, easier to prime, more reliable and compact blaster.