Hey BMoor!
 
I have been collecting some more and I have recently put together a R/B burn deck, but it has some weaknesses and I couldn't think of anyone better to help than you. Here is my deck list:
 
Creatures:
 
4 Gathan Raiders
4 Severed Legion
2 Nekrataal
 
Spells:
 
2 Cone of Flame
4 Tarfire
4 Lava Axe
4 Shock
4 Incinerate
1 Beacon of Destruction
4 Terror
3 Eyeblight's Ending
 
Land:
 
2 Spawning Pool
1 Keldon Megaliths
2 Graven Cairns
4 Terramorphic Expanse
10 Mountain
5 Swamp
 
This deck has proved pretty resilient against pure aggro weenie decks, but it can't stand up to a constant beating. I have a pretty long losing streak against one of my friend's elves/treefolk deck, which is able to pump out creature quicker than I can kill them. I am always without cards in my hand so thats why I have Gathan Raiders, for an easy 5/5 sometimes on my fourth turn. But again I have not faired too well against a more aggressive deck. Do I put in a few pyroclasms? This is a casual deck, but I do bring it out for FNM every now and then, so if you could keep it standard that would be great! Any card is open to take out, so nothing is sacred. I really need your help!!
 
Sincerely,
Brandon

The first thing that looks out of place here is Cone of Flame.  It's not bad, but your deck is already packed with ways to dole out damage 2 and 3 points at a time.  By the time you hit 5 mana, is there anything left Cone of Flame can kill?  Remember, it can't target the same thing twice, so the most it can deal to any one target is 3 damage.  And if your opponent has less than two creatures left, you have to hit yourself or our own creatures for some damage-- and in your deck, I'd be surprised if your opponent has two creatures left that a Cone could kill.  You'll be happier with more copies of Beacon of Destruction-- what you need is a few large doses of damage, not more small ones.
 

Speaking of "later in the game", the weakness of a deck of this nature is its inability to make it that far, because it burns up all its fuel (pun intended) while other decks build for the late game.  How can you remedy this?  Well, replacing some of the smaller burn (Tarfire) for heavier burn (Browbeat) is a good start.  Fortunately, your black splash gives you access to exactly what Red needs to overcome these obstacles-- life gain, card draw, and discard.  For the life gain, Soul Feast is probably your best bet.  Black's card draw has suffered recently, but there's still Graveborn Muse or Phyrexian Etchings if you don't mind the life payment.  And for discard, well, the options are myriad.  I personally like Augur of Skulls or Hypnotic Specter.  The Specter would probably be more useful than Severed Legion, and the Augur would also make a good blocker to go against opposing Treefolk.