I have just been working ona load for my 9.3x62 and with 286grn Barnes X it shoots best with 57.5grains of H414 which is .5 grains over "book max" With this load, the groups genuinly average 1" with a few at 3/4"...I suspect I my shooting is actually the limiting factor to getting more consistant 3/4" groups...

Anyways, I am seeing absolutely no pressure signs on the cases and the bolt lift is all OK..However,I am a little worried as the temps today have been in the high 30sF to low 40'sF and I want this load for RSA when the temps could be in the 80'sF

Max velocity is not the issue here, but if I reduce the load even 3/4 of a grain, the accuracy starts to go...

Any thoughts or comments on this?

Regards,

Pete

I worked up a load of H414 for my 338-06AI in cold temps cause I thought it would be cold in Namibia in August. Well it was freezing in the south, east of Keetmanshoop but up north around Etosha Park it was sweltering hot. High 90's or 100 degrees f. in the shade. And there isn't too much shade! I had no problems with a max load. I don't know why it isn't included in their Extreme Series.

I used the 225 Barnes X.

Pete-Do like I have done, get ammo and gun warm
in front of heat outlet then go out and try it..See if any pressure signs show up.Ed.

My experience in a 338/06, is that H 414 is too slow for that application. This is contrary to a lot of load data, because of the lawyer induced trend to strive for lower pressures, and the powder companies wanting you to go thru more powder. The myth of 90% load density being more accurate is also only true if one uses slower powders.

I found exactly what you did, in my 338/06. Reducing the load slightly caused accuracy to fly right out the window. I am sure pressure drops off real quick is a good reason why this is happening.

My own personal theory based on experience with no scientific support( the disclaimer for the constant complaint crowd), is that all powders have a certain pressure curve that delivers good accuracy or not. The case size and the bullet weight ( resistance to the pressure explosion once the primer sets the powder off) need to be in harmony with the burn rate or explosion rate of the powder.

I use for an example a 243 winchester that has a real accuracy problem. Factory loads etc, it gives 4 and 5 inch groups at 100 yds. It does that with a lot of handloads also. However, if I load it with fast powder and varmint weight bullets, it turns into a one hole shooter. EG: Blue Dot, 22.5 grains and 80 grain Winchester SP.

Then if I take a Varmint weight bullet once again, like a 55 grain Ballistic tip, or a 60 grain Sierra Hollow Point and push them to 4000 fps with H 380 ( 50 grains) like listed in the Nosler manual it is also a one hole shooter at 100 yds.
However, if I back the load off to 39.5 grains, the groups start opening up instantly. If I go to 50. 5 grains the groups open up instantly.

The tightness of the bore also comes into the "harmony" balance here. This rifle sucked fresh out of the box. It was sent back to Winchester and they returned it, and said it was in specs.

I called Winchester and spoke to the tech who worked on it. He once again told me it was "within" factory specs. a 4 inch group at 100 yds, was considered "within specs"!

So I asked him how close it was to being "out of specs"? His answer was " awfully close."

So I just planned to rebarrel the thing. The only reason I did not get rid of it, as the rifle was blessed with a stock with awesome looking wood. However the rebarrel didn't happen when I learned that the Faster powder loads and the mid range powder ( H 380/50 grains) and the 55 and 60 grain varmint bullets shot so well.

I will eventually change the barrel when this one goes to pot, with those loads.

Hope this was followable, as I am a bad explainer some days, LoL. Also hopes it helps out a bit.

Cheers and Good shooting
seafire