reduced imr 3031

[TREERAT]

in a .358 win, showing a max load of 49g in lee manual for a 200g j bullet, can imr be reduced to 30g as a start load for a 196g cast? if my figures are correct this should be 61% of the listed max, which is by the way a compressed load.

[44man]

I don't think I would go less then 40 gr, 43 would be safer.
I don't know how much reduction to a medium powder you can get away with.
You have to keep the SEE event in mind. I don't think you need a real slow powder to have it happen.
Need someone here to answer that question.

[TREERAT]

UPDATE: just verified mycase holds 42.2g IMR3031 to base of a seated bullet.

[felix]

SEE can happen at any time, but almost never with a load that delivers less than 100 ES. Keep the powder close, or powder plus filler (dacron, poly balls, etc) right at the boolit base, to aid consistent ignition. ... felix

[C A Plater]

My experience with IMR3031 in other calibers is that it reduces fairly well for managed recoil loads. IMR4895 worked as well or better for reduced loads too. The biggest issue I've had is inconsistent ignition from a less than filled case making for erratic velocities and poor accuracy. I use 30.0 grains in my .38-55 which has a similar capacity and it performs well with a heavier bullet so if it were my rifle I would use that as a starting point.

[TREERAT]

felix, when you say 100 ES. forgive my ignorance but what does ES mean?

[felix]

One shot at 2100 fps. The second shot at 2200 fps. ES=100. ... felix

Extreme Spread.

[TREERAT]

Ok, I get it- extream spread. thanks

[runfiverun]

358's are pretty friendly to near max j-word loads with cast.
mine really,really likes the saeco 245 and 48.5 grs rl-19.

[oldtoolsniper]

I just pulled down my copy of “Handbook for shooters and reloaders” by P.O. Ackley and it contains an entire chapter on reduced loads. Of interest is the number of rifles that blew up while the shooter was using a reduced load. Apparently in a large case with a small amount of powder the primer can cause the powder to detonate rather than burn. It contains a whole chapter of information from Ackley, Speer Inc. and various other shooters as well as explanations from CCI in regards to the use of regular and magnum primers.

[felix]

The longer the case is, the more square the case is, the more SEE becomes a reality. Only the primer is supposed to detonate, and not the powder. Excited powder will detonate every time. The challenge is to never excite it, either by excessive flame, heat, or accumulative wave action. Ignition should always occur from one direction, and that is closest to the primer. ... felix

[44man]

I do not know if my thoughts are correct. If primer pressure moves a reduced charge forward and the boolit also moves out but the powder does not ignite right away, the boolit can act as a bore obstruction, sending the pressure wave to the rear when the powder does burn.
Felix is right, that the burn should start right in front of the primer, not up in the case. I firmly believe the primer sends a pressure wave out to push everything forward before the fire and heat can act on the powder.

[oldtoolsniper]

Felix and 44,
You are both saying the same thing as he is.

In some of the cases the powder was pressed against the boolit and they were able to dig it out of the casing with a small screwdriver with only a small amount of the powder scorched or burnt. He states that the Ordnance Department and DuPont noticed the phenomenon with test rifles in the vertical position.

He then explains how companies back then tried to hush it up to not hurt sales. He goes on to say “that the truth would be far better than keeping hand loaders in the dark. All suppliers of reloading components stock a wide variety of powders. Within the lists are powders adapted to specific applications, so the correct powder could just as easily be sold, as to try and push some number which may result in an accident. Certainly one accident hurts the game more than the simple truth.”

Good advice in 1962 and I would say it’s good advice in 2009.

[felix]

Your thoughts are correct, 44man. Also, if and when any vibratory wave action external to the case exists that creates the natural frequency of the powder, ignition will occur, and that is with or without the primer being involved. Happened when someone was ramrodding a stuck loaded round back out. The case became the projectile. ... felix

[44man]

Your thoughts are correct, 44man. Also, if and when any vibratory wave action external to the case exists that creates the natural frequency of the powder, ignition will occur, and that is with or without the primer being involved. Happened when someone was ramrodding a stuck loaded round back out. The case became the projectile. ... felix
I read about that. It was a BR shooter with a stuck live round. He removed the bolt at his bench and was trying to pound out the round. It went off and the case shot out the back and hit his wife.
We deal with danger every time we load a gun and to stray from printed material can result in disaster.
Those that download or seek super velocity tread a thin line.
Even with my 45-70, data for 4759 was lacking and I did research for weeks before dropping the hammer on a load.
Guesswork is not Kosher.