Determining Maximum Powder Charge

[scope eye]

If you are going to use H4350 then try RL17 the results are usually better as far as FPS anyway.

Tanks Dean

[MZ5]

H4350 was actually my original plan for load workup, but i can't seem to find it anywhere around me. I can find imr 4350 but have heard it is different.

Would varget be better suited with a lighter bullet. I was getting great accuracy with it sub 0.25moa.

The IMR powder will work well, as most all IMR powders most always do. You are correct that it IS a different powder, so use IMR-4350 data, not H- data.

If Varget is working well for you, by all means keep using it. Just might want to give some thought to backing down the charges a bit.

[Jamie]

However, with a bottleneck rifle case, thanks to the relatively slow powders in use, the high engraving force that causes the greatest pressure rise and the relatively small reduction in case capacity from seating the bullet deeper, the pressure increase from seating deeper is usually more than offset by the decrease in engraving force (thanks to extra bullet inertia from the "running start" the bullet gets on the lands) and the net result is pressure decreasing as you move farther from the lands. You will eventually reach a point where the extra freebore doesn't help anymore and the reduction in volume takes over.



Isn't that what I said? Close to the lands it could help far from the lands it wouldn't and reducing COAL increases pressure.

Don't underestimate the pressure increase from reducing case capacity. It only takes 1 grain of powder to go from safe to stuck bolt.

[helotaxi]

Yes, but one grain of powder might be 2% or might be 4% of the total charge weight, while seating the bullet 0.050" deeper might only account for 1% of case volume. Obviously the bigger the bore with regard to the case volume the bigger a difference seating depth makes in case volume. Regardless, as far as seating the bullet deeper in the case goes, bottleneck rifle cartridges are not nearly as sensitive and straight-wall handgun cartridges.

[Jamie]

Lots of "might"s in that. At the end of the day, if you put 30 grains of powder in a case and put 30 grains of the same powder in another case that has less capacity, your pressure will be higher. You can see this in using different .308 cases from Remington and Winchester.


Back to the OP,

"Like others said, you have to rely on several factors when determining the max for your rifle. A lot of the Savage rifles I have had lately seems to have slightly oversized bushings and I get cratering with minimum loads. Flattened primers will tell you things as well as shiny pots on the case head. Hard bolt lift will tell you most times but if you have a really rough chamber then you may get a sticky bolt before you reach your max."

[helotaxi]

A flat primer is just as likely to tell you that you have "generous" headspace as your load is higher pressure. Primers lie, plain and simple.