The 109s had staggered 7mm guns, one about 3-4 inches longer than the other.
One would protrude from the cowling a couple of inches, the other would extend about 4 inches more (roughly). This was due to the staggered ammo magazines in the nose.
I can't find a good reference picture online to link to right now, but the port barrel would be longer.
This was changed in the G series when the 13mm was introduced. Those were symmetrical. So 109E4, 109F4, 109G2 should eventually get staggered guns in the cowling.
Like I said, minor, but something for the "to do" list.
