Yes, there is. Metals are not all the same. The chamber, the bolt itself, the casing, these are all made of metals that are specifically well-suited for those positions. One of the reasons brass is used for casings, for example, is it can flex without breaking whereas a chamber must be made of something else that cannot flex without cracking/breaking/etc. Also, brass's expansion and contraction increases the pressure of the explosion inside and "squeezes" it at the projectile. One could surround the rear ninety percent or so of the bolt with an explosive material, but that is not nearly as potent as a normal casing and more of its energy is expended battering the chamber instead of re-orienting on the bolt and would lack the pressure increase and "squeeze" direction a casing would provide.





There are more reasons and explanations and even more possibilities.





Besides, this is the STC printout they have, doing otherwise is heresy, heresy is punishable by a whole Warp lot worse than death.

