I don't know enough about GRT to advise, but I have done enough load development to know that the computer output from GRT is just a guideline, and always needs to be physically verified.

I know that some people can get the computer to agree with what they shoot on target as far as calculated nodes go. I do question if another shooter behind the same rifle with the same ammo on a different day is going to get the same result.

I do not use GRT to tell me what a node is, I get the optimum charge for a given bullet, powder and seating depth from OCW testing.

In fact, my only use for GRT now is to determine when powder burn might be 100%, which if true will show up as low ES.

If you're not doing any OCW test, then three or five shot groups are not reliable indicators, you should increase that to 10 rounds.

big5ifty,

What is your OCW method?

I do not shoot precision and LR shoots - the loads calculated by QL and GRT  have always served me good enough to practice and bring the venison home.

What is your OCW method?

I do not shoot precision and LR shoots - the loads calculated by QL and GRT  have always served me good enough to practice and bring the venison home.

It's the one described by Dan Newberry .

I'm not a critic of GRT, it's a good modelling program, I find it very useful.

A well put together rifle with a sound barrel is going to shoot regardless, well enough for hunting purposes.

For example, this past weekend I resumed testing of my LR primer replacement in a BMG case, and at the same time, I had a batch of Lapua headstamp brass that I bought already primed. I'm using TZZ brass at the moment, and I could have deprimed the Lapua and re-primed the TZZ, but I have experienced misfires from primers that were removed and reseated in the past, so I decided to burn some powder with the Lapua brass and see what comes of it.

I had 4 different bullets, two different powders, and three different primers, with two types of brass. I used the same charge of powder type across the board, 220 grains of US869 and 225 grains 24N, irrespective of bullet weight or headstamp. Lapua brass is 10 grains less water capacity than TZZ.

My LR primer test was 8 rounds, the rest varied up to five, when a load gave me a less than completely smooth bolt lift, I stopped and moved onto the next one.

Other than the point of impact change per group, there was very little difference between them as far as group size goes, everything within 2 moa at 100 meters. Velocity variance between groups was [ from memory ] around 2-300 fps.

The point being that if everything is right with the rifle and the scope, the ammo will perform to within that capability regardless.

This was not an OCW test, it was just an exercise to gather as much data as possible using the last of certain components and getting some practice at the same time.

That generally is true, that a sound rifle shoots most loads and variations well. But I think there are some caveats to this rule. A light hunting barrel is more effected by barrel harmonics, than heavy varmint barrel. Both are equal in their accuracy potential, but a heavy barrel is more forgiving.

I also find a lot of truth in that the most accurate loads are often close to max pressure. And by max pressure, this is specific for the rifle, not as per the reload manual.

I agree with the above, about some rifles(being good) will shoot accurately with many loads- ammo.
I have found thicker barrels shoot better.
I have found that most people have no idea how fast a thin barrel is affected by heat_(No even faster than that)
I have found that inaccurate lower velocity rifles (within reason) shoot better with the lower end of loads. .30 - .303 - 7mm 08
....................I have also that high velocity if problem rifles will sometimes come right at the very edge of stupid loads. .270 - 220 Swift -243

All of Treeman's above post is absolutely true, and I confer from experience 8)