To address you question of difference between SST & Interbonds:

There is a difference that I found in my 7mm08. The SST's and Interbonds do not shoot the same in the same load. In what is a very accurate load of IMR 4895 40.5 grains in the SST (.75 inch average), the same load with the Interbonds was around 1.5" average. I never go the Interbonds to shoot sub MOA in my gun after trying several different powders. May just be me but that's my 2 cents worth.

I reloaded for the first time the other week and I loaded my .308 with hornady interbond 150g with:
IMR 3031 44g
IMR 3031 43g
IMR 3031 40g
IMR 4064 44g
all with cci 200 lg rifle primers.

I went to shoot the other day and my rifle was all over the place.... I was scared to death.. I thought I was going to have to salvage the thing. I then shot my factory hornady SST 150g loads and it grouped 1.25" like it normally does. I loaded a with a friend a couple of years ago with IMR3031 43g with hornady 150 btsp and it shot under 1". I havent reloaded since then. but my question is, the only thing that could have gone wrong is case length. I set the case length to the max at 2.810(i think that is what it was). In the hornady manual it says the case length should be 2.735. What in the heck could have gone wrong? Is case length that critical...could that have been a factor? I read that the max length will be more accurate cause it sets the bullet further on the rifling. Help please.... I thought reloading was going to bring my groups to less than 1" again.. Now I am going to have to shoot my factory this weekend on the hunt. Please help with some suggestions? dont let me be afraid to reload again.. I measured the powder to the grain... what could cause these groups this large. Would the interbond bullet behave that much differently than the SST? the only thing I could think of is the loaded cartridge being the max length??????

Without knowing the make, model and twist rate of your 308, it is difficult to diagnose what is the problem.

Firstly, don't confuse "case length' with "cartridge length". Case length for 308W is 2.015" and recommended overall cartridge length (i.e. case + projectile) is 2.750".

With an overall cartridge length of 2.810", I would suggest that the bullet was engraving onto the lands which is incorrect. For best accuracy in modern rifles the bullet should be seated to be just short of the rifling. Depending on the neck tension, some projectiles may have been pushed back into the case by the rifling (i.e. loose) or if heavily crimped then the bullets had no free play (the bolt would have been tight to close)

Each time you load a different brand, weight or style of projectile you will have to determine the correct seating depth to ensure that the projectile is not touching the lands.

I did notice that with a catridge length the bolt took a little effort to close than normal. I shot two 3 shot groups with each load with a cool barrel on each group. How do I determine the best OAL of the loaded catridge? How do I measure if it is in the lands or not? To get the best length is it better to trim the case below the max length or to seat the bullet deeper. BTW the bullets seated very easily.. Thanks for all your help.

There are a lot of things for you to check, but this is quite normal. I'd start with reloading technique. Are you requiring excessive force in your sizing operation? Is your bulet seating smooth and easy? Either of these can produce reloads that are far from concentric, and acuracy will go right down the tube. As far as seating depth the only critical dimension is the length to the ogive. As long as your action opens and closes smoothly don't worry about the OAL. The front end of the bullet isn't touching anything anyway. Some bullets prefer a sizable jump into the lands, some don't. Just take your time and be aware of what's happening at each step of the process. Best wishes.

Cal - Montreal

Since this is your first post under that username, I'll assume nothing.
Did you just fire one bullet each in the above loads? If so, expect it to be all over the place. Accuracy is nothing more than repeatability.
And about the longer case being more accurate, there's some confusion there. Many bullets do their best work just off the lands, even "kissing." But that has very little to do with how long the case is. You need to check the chamber in your rifle, to see how long you can seat your bullet before running into the lands, then back off just a couple thou. If you don't do this, and seat too long, then you chamber the bullet into the lands themselves, which can cause extremely dangerous pressure spikes, and you may mean it differently next time you tell us your gun was "all over the place."
Try loading up five each of any of those loads, using the same make of brass trimmed to the same length (length of your shortest piece), and seated just off the lands.
There's a lot to learn about reloading, before you can expect any improvement over factory ammo. Those guys know what they're doing, and with all due respect, you don't. If the factory is shooting good for you, take it on the hunt, and spend the next year learning all about loading, and how to make your gun shoot. You should cut MOA no problem.
As for being afraid to reload again, well, again assuming nothing, you should have at least a healthy respect for the fact that you're putting together little bombs that if made incorrectly, could blow your face off. Something to think about, you know.

max load for imr 3031 is 41.5grs you are at 44grs loaded near or into the lands. probably would spray all over.
I rccomend you get a reloading manuel and read the how too's before you continue.
DO NOT TAKE AN OLD LOAD AND START REPLACING COMPONETS.
rEDUCE THE LOAD AND WORK UP!!!!!