I have a lot of very early Accurate MR-3100 powder that I started loading with 180 grain bullets. This powder seems to be the same burning rate of original H-4831 as velocities fall within 10 fps of each other. Accurate's guide listed 59 grains as maximum with all bullets between 150 and 220 grains. I loaded up to 60.5 grains, which is into the neck but, found no undue pressure signs. I tried to estimate pressure using the Powley Computer and came up with 55,800 PSI. All my manuals record pressure in CUP so, I really don't know if I'm running too high pressure or not. I would like your comments. Thanks

The load in the data from Accurate is listed as a compressed load- I personaly would not exceed the "book" in that instance. What is your the velocity of the 59gr load in your rifle and the 60.5 gr load? Compare the increase from 58-59 to 59-60 a big increase indicates a pressure spike- pressure spikes are usually followed by case failures.

Dear Joe,
I believe that Ray Atkinson once wrote here that you couldn't put enough 4831 into a 30-06 case to cause a problem. Your Powley sounds like it is about on the money, and 56,000psi is about the range for 270Win. I'd say you are OK.

One means of testing is to take five cases and shoot them with your load sectioning one after five reloads. If there are no signs of case failure, load another three times, and then section another case. Eight reloads is a goodly number.

If you have no indications of case thinning, primer pocket enlargement, or necks splitting, go for two more reloads and section another case. If you can get 10 reloads out of brass, explain to me exactly what the problem is!

I'd suggest you neck size only, doing a fully length resizing only when you have difficulty chambering, then go back to neck sizing. I assume you want to use this load because it is accurate. If accuracy is not an issue, then you can get better velocity with 4350. Kudude