Bedding your gun may not be the solution you are looking for bud.
Before I get started, I'm a bit cynical and sarcastic. Not meant towards you. Just meant to add some entertainment to the reading. (This crap can be really boring)
Who the hell am I to lecture to anyone? I'm nobody. I state that now. I build guns and some have done very well in a variety of competitions and a few other places.
Ok, enough with that.
Assuming your ammunition, optics, and scope rings/mounts are of good quality and you know how to pull a trigger, what we need to look at is your shot groups.
Now, one three shot string isn't going to tell you much. It doesn't say anything actually. Neither will six shots or even ten shots on a clean barrel.
We need average predictable performance levels.
If the bore is clean, blast 10-15 rounds down range any way you want. Blast a few rocks or something. The bore needs to get fouled and it needs to "settle down."
Now, bag or bi pod the rifle and begin shooting five shot groups. I'd do this until you had 25 well aimed rounds down range. (More certainly won't hurt) let the barrel get warmed up. Don't fret about the heat from 35-40 rounds of ammunition fired in a continuous slow fire pace. NRA highpower course guns see far more abuse and they shoot fine all day long. No worries of making your barrel like Chernobyl. A 223 bolt gun will run for at least 7000 rounds.
Now, begin examining your shot groups.
This again is assuming everything else is right. No parallax in your scope, no loose rings or bases, bad ammo, etc. . .
1. You can't hold elevation to save your butt. (Meaning you don't hold the same on the target for each shot fired)
2. Ammo was/is loaded with thrown charges (I'll come back to this)
3. Bad fit between receiver and stock.
4. Bad crown.
5. Barrel is touching the stock someplace (if floated)
If you are shooting a 223 at 100 yards, this isn't going to apply to you. the bullet is going so fast that if there's velocity variance between one and the next from having charges "tossed", it won't amount to anything on paper. Bench rest proves this. All the top dogs throw their charges and they compete from 100 to 300 yards.
Long distance is another story. The minute variations in velocity that don't do anything at 100-300 yards suddenly make for big changes out at 600 and beyond. Here you have to scale your powder charges.
Big round groups:
1. You are looking at the target instead of focusing on the reticle.
2. You have a lemon for a barrel.
3. Not enough or excessive guard screw torque.
4. Bad crown.
5. Crap ammo.
6. Twist rate doesn't match the bullet weight.
Tight to reasonable group with an "orphan" out in left field.
1. You jerked it.
2. You load your own and don't pay enough attention to detail.
3. You bought ammo and got a bad one.
4. You're crown is goofy.
5. You're gun needs bedding.
6. Guard screw torque needs to be fussed with.
Tight to reasonable groups shot on different days with the same lot of ammo that are always at a different location on paper. (point of aim verses point of impact)
1. Your gun needs to be bedded.
2. You are very clumsy and keep banging your scope around.
3. You keep cleaning your gun after every time you shoot. (more on this)
Clean your gun's barrel when you notice an obvious reduction in performance/accuracy. Who cares if its coppered up as long as its shooting well? Seriously. As long as its not loaded up so bad that you are smoking primers from high pressure (extreme case) you are fine to leave a barrel fouled. Your better off actually. Leave the "cold bore clean barrel shots" to the "snipers" on TV.
1. Velocity of ammunition is too slow
2. You don't hold well.
For what ever reason, slow ammo seems to string left and right as opposed to up and down. Don't know why, but it's something I've noticed after testing hundreds of guns in a tunnel.
Bedding done properly will do the following:
It'll settle down a gun that changes from one day to the next.
It'll tighten up good groups and make them even better good groups
It'll reduce fliers.
It'll repeat point of aim/point of impact in any weather and no matter how many times you take apart and reassemble the rifle.
What it won't do.
It won't fix a lemon barrel
A bad scope
Bad/poor quality rings/bases
A bad trigger puller. . . .(ahem, ahem. . .)
Some may feel compelled to come back with questions about lock time, lapped bolt lugs, etc.
He's shooting from a bag, if lock time is a concern when bag shooting, then he's a really bad shot and nothing is going to fix him.
Lapped lugs are pretty much useless.
WOAH, what did he just say?
I said they are useless and I can prove it to you.
Pull the bolt from the receiver and look at the cocking piece. chances are its ground/machined at about a 45 degree angle. So is the sear on your trigger. Cock the bolt and put it into battery and what happens? the cocking piece loads on the sear and attempts to ride up it until the top back half of the bolt loads against the top of the inside bore of the receiver in the back directly behind the ejection port. If its picking up in back, both lugs can't be touching up front. Only the bottom one is.
It's only going to get worse as the gun gets older.
The action of lapping something is intended only to improve surface finish. Bolt manipulation should feel smoother once the lugs are lapped, but that's about all its going to really do.
There are two actions that are exceptions, Nesika Bay Precision and Borden Actions. These use the patented "Borden bumps" that mechanically lock the bolt dead center while in battery.
Sorry, I don't mean to sound like a "know it all". I'll attempt to save face and show a few examples of bedding jobs I've done. These are all done with my two grubby hands and they are on real guns that get used.
The orange stock being the exception, it's a work sample and props to go anyone who can figure out why. (The boo boo is in the photo)
Hope this helped or was at least mildly entertaining.