Laser Pistol -vs- Rifle

Is there an explanation why the Rifle can be set higher per SEU than a pistol?<br />I was thinking it has to-do with the size of the crystal membranes (larger diameter or longer).<br /><br />L<font face="courier new,courier">aser Pistol - 1d10 per SEU, Setting 1-10 <br />Laser Rifle  - 1d10 per SEU, Setting 1-20 <br />Heavy Laser  - 1d10 per SEU, Setting 5-20</font><br /><br />Thoughts?<br />