Edit: after doing some number crunching and logical reasoning, I have concluded that despite the overwhelming cost of the crystal bow, after it's fifth charge the crystal bow is actually in proportion with the rune crossbow in cost/damage and even doing more damage than the crossbow with broad bolts. This makes the crystal bow (with the "switcheroo bow" trick) the best to grind in training range. I have abandoned the msb rant/argument because of my ridiculous overlook (msb is a lvl 50 weapon and the rune crossbow a lvl 61 weapon.) Therefore, there really is nothing left to do with the rant except anything opinionated (e.g. I think shortbows should be updated to at least be more more common for the poorer class, like a lunar ring to the seer's ring, a torso to the bandos chestplate, an obsidian sword + zerker necklace to the saradomin sword, etc.)
All of you seem to forget a handy little fact: MSB is MORE expensive then rune crossbow. Also, my damage calculations are putting rune crossbow ahead of MSB in terms of cost, specifically that the 6k XP difference doesn't make up for the cost unless you earn over 1.45m per hour, in which case you should be using chinchompas to train anyway. Let's see the numbers you used, and I'll point out where you messed up.
If the numbers you're looking for are the msb + adamant arrows vs rune crossbow + broad bolts/adamant bolts, I have a [hide] damage table over the course of the (hypothetical) time/cycle in the first post.
If you're talking about the crystal bow vs rune cbow + broad bolts, here are my calculations for the crystal bow damage output > cbow damage output:
Crystal bow max = 25 x 6 speed = 150 max damage per cycle
Broad bolt max = 28 x 5 speed = 140 max damage per cycle
I already agreed with the fact that msb is more expensive in terms of gp/ammo/damage.
And I completely forgot about red chins which are obviously the best exp/hour. I was saying the crystal bow is best "cheap" way to grind since it can cost 72-360 gp per shot where as red chins cost in the several millions to gain good exp. I'll go change that in the edit.
In the first sentence you said the msb is more expensive. But in the second sentence you said the crossbow is ahead in cost. "Ahead" in the meaning of more costly to use (therefore worse), or ahead in the meaning of more advantageous (cheaper)? I just tend to get hung up on words sometimes. But that aside, are you using weaker hitting ammo in the calculations that has better damage per gp (like maybe iron or steel) instead of going all out with adamant or rune?