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Okay, so following a little advice I'm going to try a slightly slower burning powder behind the 70gn Nosler BT pills.

I've opted for IMR 4350, firstly because Nosler themselves provide data for this load (although IMR don't), secondly because the 4350 will be dual purpose and allow me to work up a load for Fallow using 100gn soft points from Sierra.

The N150 will be redeveloped into a 55gn load using Nosler BT's (which should, according to the charts, give me a 3" kill zone out to around 250yards).

So, the IMR4350 load I'm about to try is in steps from 43gns (Nosler's base point) up to 47gns (98% fill and Nosler's most accurate load).

I'm going in half grain intervals, so 9 steps up to 47gn (if indeed I get that far). Questions are:

Should I be starting 10% below minimum (I think not)?
Is it worth going in single grain steps to begin with and fine tuning when I get a group that is tight (so only 5 steps, five shots each)?

Caliber is 243, barrel length 22" I'm hoping to get somewhere between 3250fps and 3610fps, which should help expansion.

Start at minimum load. Below that can also be dangerous.

Odd that Nosler give data but IMR don't? But yes, Thanks for your advice I'll start at 43gns.

Do you think single grain steps would be okay till I get into the ballpark?

I'd stick with half-grain.

I would be inclined to go up in .2 grain steps and drop a half grain at the first hint of heavy bolt lift

I've gone in half grain steps for now. If there are any signs of excess pressure or stiff bolts I'll note it and back off. Hopefully, everything will be fine up to 47.

Once I get a good group I'll then bracket either side in .2gn steps. Interestingly, Noslers data doesn't state a minimum; just a starting load and a maximum which is also the most accurate load (47gn).

I would advise that you sit down and completely rethink your approach to hand loading as from you posts on here it seem cavalier to say the least.

Firstly you are only relying on one source of data, Nosler. Not good practice.

Secondly if IMR don't list 4350 with that weight of bullet they will have a reason for that, an email to them could be helpful and illuminating.

Thirdly your wish to go up in 1 gn increments, especially when you are working up to top loads in a rifle that has already shown itself to be giving high pressure when used within published data is playing Russian roulette.

Fourthly a stiff bolt is not "pressure sign" whatever that might be but an indication that you have fired an overpressure round in that rifle. Not good for you, not good for those around you and not good for the rifle.

Before you fire any of these rounds I suggest that you find at least two more pressure tested sources of data for IMR 4350 with a 70 gn bullet and use the lowest recommended starting point within those sources. Work up in .2 gn increments using a chronograph to relate your loads to the data you are using so that you don't need to rely on spurious pressure sign and dangerous situations like stiff bolts.

In reloading manuals all a recommended accurate load means is that that load was the most consistent performer giving the lowest extreme velocity spread at a safe pressure at high velocity, WITH THEIR EQUIPMENT. NOT YOURS!

it does not mean that it grouped well only that from the velocity and pressure data it theoretically should group well.

That is why working up loads is so important.

Why are you looking for such a high velocity anyway? In my experience Noslers expand very well at much lower velocities.

Further to the above Lymans pressure tested data for example with IMR 4350 under a 70 gn Sierra HPBT recommend a starting load of 40 gns with a maximum of 45.5 gns.

Sounds to me like a far better starting place for you, also you really need to get access to a chronograph, you are risking yourself and those around until you get a better handle on your rifle and the loads, guessing, rushing and looking for load book maximum loads are not safe options.

Dromia, I think what you have said is at least partially valid, but it doesn't come across well, at least to me, seems a little preachy.

The half-grain increments are fine - working up from a light load going all the way in .2gr takes a very long time. I use .2gr near the top end, and if a .5 is the next one up and I get pressure, I won't shoot it.

Nosler's start load is fine, they are normally pretty light. Loading manuals, as a rule in the modern age, err on the side of caution. The start load is a safe enough one, usually very light. No sense starting below it.

As for needing two or more load sources, sorry, but no. If you're working out the top end, great, but working up from start load is fine with one reputable (ie published) source. I don't think he's done anything wrong, or dangerous. It's just different from what you'd do.

Fine you can shoot beside him if you will but from what I've read here then I wouldn't.

Sorry you see it as "preachy" but safety is important to me and I say it as I see it.

His approach comes over to me as a bit dubious, as does yours and not one I'd recommend, as it is fine for you then you keep him right.

At the end of the day he will do what he chooses to do, as will you, regardless of what I say. I've said my piece, tried to help and I am now done with this thread.