lyman saum data.pdf
Originally Posted by X-man
If your velocity is within reason then you are correct.
If your velocity is over what is listed in pressure tested data your brass is holding, but you are placing yourself in some form of risk. If you are a few hundred fps over pressure tested data you are in imminent danger.
More than just the brass there is the matter of the action taking the strain...year after year.
The reason I am making noise here is I believe elkaholic has a cartridge about the capacity of the 300RSUAM. Yet he is 250fps over what normal speeds in that cartridge.
Worse than that he is 100fps faster than what is recommended in the 300Win magnum with IMR-4831 by 100fps!
I don't think Elkaholic is stupid or anything else derogatory. I read a few of his posts and he seems totally on the ball.
After the 416 incedent and another friend blowing up a rifle because he could not "read" the pressure in his rifle in the conventional way I bought pressure testing gear.
The truth is you don't need pressure testing gear you just need a chronograph and need to know the cases capacity and you are set.
But that is enough.
The only other guy to raise a red flag was BartB....So that is me done on this subject.
I wish elkaholic well and safe.
Here is the data from the LymanReloading handbook (#48)
When I develope a wildcat, the first thing I do is reserch similar rounds, especially in the area of case volume. I then start a few grains low and work up to what I know is absolute max based on what I see with the cases, chronograaph, and how it compares to known data. I then back off from max and try to find the best velocity coupled with good accuracy. I try most of the powders in the burning rate area that I think will work best. In the case of the 300 Sherman, I found IMR 4831 to give both top velocity, and accuracy near max. It happens to fall right in the area of the IMR loads in the saum, although it wasn't the top powder for the saum. I quoted 64 grains at 3050'. You will note on the Lyman data that they do not list the 190 but it fits nicely between the 180 and 200 grainers listed.
The 180 being 64.5 grains, and the 200 62 grains. You will also note that the top velocities listed are in the mid 2900's for the 180 and not too far short of 2900' even with the 200's. This all with a 24" barrel (important to note as mine is 28") Also, as I previously mentioned, my case holds a couple of grains more than the saum and has a longer throat as well. Anyone knows that allows you to load the same charge for lower pressure or bump it up to equal pressure for more velocity. (ARE YOU WITH ME SO FAR)? The avg. of the two top 180 gr. loads is 2942' and the 200's is 2866'. If you avg those two you get 2904' which should be very close to the top load for a 190. (ARE YOU WITH ME SO FAR)? One could speculate that I would gain something from the extra capacity and throating. Let's keep it small and say 25'. Most people would agree that approx. 35' per second for each inch of barrel length applies in this case. So here we go:
4x35=140' + 25' for capacity and throat. for 165'. Add the 2904 + 165 and WOW! It's actually 3069', not 3050'. Imagine that! I don't think there is much room for argument so far, but you never know! Now for the outrageous pressures. If you look over at the right margins you will see pressures listed for IMR 4831 at 64,000 for the 180 and 62,900 for the 200 grainer. WOW! It's actually 17,000 short of 80,000! (ARE YOU STILL WITH ME)? Any more questions boys? If there is, I'm afraid you may have a little "lube on your primer"!!..........Rich
I just posted this before I saw x-mans reply. Maybe Bart has something brilliant to say?