Hi guys,

Some writers suggest that Hodgdon's H380 extruded powder is relatively sensitive to variations in ambient temperatures.

Though I've just developed a cracking load
for .22/250 with 38.4 grains pushing a 55 gr V-Max at 3600 fps, I always take care to keep my ammo in the shade. Particularly as I've been test shooting in the English summer sun and shooting foxes through cool English nights all year round.

I'd like to hear of real evidence of the kind of variations others have experienced with this and other extruded powders.

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Haven't heard about H380, but H233 has been a little heat sensitive but it is very small amounts for very small groups ( 0.2-3 of a grain) With what you are shooting don't believe it would be a problem. The best way would be if you are shooting in the heat of the day set a round in the sun and let it heat up and then shoot it and take a look at the primer and see if it is much different than one at your normal temperature. Good Luck

H380 is a ball powder. It is no more temperature sensitive than other ball powders. The military uses ball powders in small arms, to a large extent because of tolerance for changing conditions in military actions. I've used quit a bit of it in 22-250 and if anything it seems less sensitive than an extruded powder like IMR4064, which I also use in that caliber.

[This message has been edited by Bob338 (edited 07-06-2001).]

I have used 380 for many years in the .303 British and it is incredibly stable and consistent. Could it be you have a bit too much powder? As I recall, the reason 380 was named that is because 38.0 grains of the stuff gave best accuracy in Bruce Hodgdon's .22-250. H380 was originally a surplus powder for the 7.62x51 NATO round and the Army takes stability very seriously. If you are not using magnum primers, you ought to. My favorites are the 5333 LR size put out by RWS. Closest thing to a benchrest magnum primer, I think.

Well guys, apart from mistakenly quoting H380 as extruded, I did read somewhere that it's a bit temperature unsteady.
Still, if everyone's experience is contrary, all the better eh?

David - 38.4 is what gives me best accuracy (overlapping holes @ 200metres), having tested 0.5 gr increments from 32.9 to 38.9. Interestingly, the final choice was between 36.4, 36.9, 38.4 and 38.9. All shot very well at 100 but differences were apparent at 200 metres.