was given some powder loads tonight for a 7mm08.
the loads were for standard 7mm08 loads, what % can i safely increase these figures to load develop a 7mm08 AI.

i know i could start off with the standard loads and work up but thought i should be careful with over pressure going into the unknown.

thanks

I always start 1 or 2 grains under the max load for the parent case. max for a 140gr reloader 19 is 49grs. I started at 48 and worked uo to 51grs before i saw any pressure signs. reduced the load by 1/2 a grain to 50 1/2 grains and it shot ok then i moved on to slower powders.
Dave

quote:

Originally posted by hivelosity:
I always start 1 or 2 grains under the max load for the parent case. max for a 140gr reloader 19 is 49grs. I started at 48 and worked uo to 51grs before i saw any pressure signs. reduced the load by 1/2 a grain to 50 1/2 grains and it shot ok then i moved on to slower powders.
Dave

So you got 1.5 grains more powder into the case? What performance improvement do you get from that?

the question was what % of increase from standard to AI.
My opinion is much the same as your's
Most of the 7mm class cartrages are low on the improvement scale as far as AI goes.
about the only thing you gain is in case life and a few feet in velocity.

quote:

So you got 1.5 grains more powder into the case

I read it that he was 1.5grs above book max for the STD. Guess it could then be a little more when compared to actual.
When I tested the 308 based AI conversions I found that at same pressure the gain was about 1% velocity for each 5% powder. In this case about 10FPS. People will claim lot larger gains comparing to posted factory velocities since factory loads to 60,000. My feeling will always be load the std 243,7-08, 308 to the same pressure you would your new AI and keep the $$$.

As to backing off .5grs from signs of pressure. What I found is that very often "pressure signs" that many talk about don't happen until you are over 70,000psi in many rifles and way beyond std pressures in all I tested. In looking at my older Hornady manual they state they simply develop a "best fit" line through the data and extrapolate it until they get .0005" expansion or a full case. That tells me that at least it that case "max pressure stds" have nothing to do with it.

Looking at Loadtech at max levels reducing RL19 by .5grs reduces calculated pressures by 800psi that is only a 1% reduction in pressure from the point of having pressure signs. Way to little margin of error for me.

But to each his own.

I would not rely to much on the numbers there only a guide .
try to look at sticky bolts, extractor marks an increse of 200f/s over a chronograph with a .5 grain increase in the load or in some loads you reach a limit with the powder velocities stay the same or start to drop off.

quote:

Originally posted by Alex.Y:
was given some powder loads tonight for a 7mm08.
the loads were for standard 7mm08 loads, what % can i safely increase these figures to load develop a 7mm08 AI.

i know i could start off with the standard loads and work up but thought i should be careful with over pressure going into the unknown.

thanks

You cannot safely assume a particular percentage of powder charge increase. This is due to the fact that all rifles are individuals, so you are FORCED to work up the load for THAT RIFLE, IF you are interested in safety!

Now, I am not saying that by using a particluar percentage of powder charge increase you are guaranteed to destroy your rifle and your head in the process, BUT that POSSIBILITY exists!

So take the coward's way out, and work up the load just as you would if the rifle was NOT chambered for an "IMPROVED" cartridge....

(Due to their capacity, taper, and shoulder angle, you cannot improve cartridges based on the .308 case just a whole lot anyway! If you really want to improve a small 7mm, start with the 7X57mm Mauser case.)