Is this possible.....?

[philthephlier]

Referring to this website on 38 spl. load data, http://www.reloadammo.com/38loads.htm, I noticed toward the bottom of the page in the 158-160 grain jacketed bullet section there are 2 loads using HS-6 powder, which I use for a number of calibers. One load using 6.3 grains yields a bit over 700 fps. and the next load, 6.5 gr., a .2 grain increase yields over 900 fps. Two tenths of a grain of powder for another 200 fps of velocity. Is this a classic example of being very careful about load data from the internet or is this really possible?

[Harter66]

Ive an 06', .3 gr makes 120fps and 5 touching a 1 1/2". So I think its possible for that gun on that day.

Do you have access to a Lyman book? "Why ballistitions get gray" there's a full page of 1 load fired in 20 some guns an 2 yes bbl. Like 300fps difference. Seems like there were 2 S&W's about 100sn apart that had 100fps between them. I once had to drive cases out of a 357 w/a minimum charge of Blue dot too.

[HangFireW8]

That page is a compilation of different sources. The guns may have different barrel lengths- snubby versus 4" versus 6" or even 8". Tighter barrels dimensions. Cronographs set at 15 feet or 25 feet and/or back-estimated to muzzle velocity. Since it is for a range of bullet weights the bullet configuration may be wildly different.

9mm & 40S&W are infamous for huge pressure increases for slight changes of bullet seating depth and/or slight powder changes.

The 38 Special is a lot more forgiving.

[geargnasher]

I'd say that isn't typical, usually it's more like 15% per grain up near the top end, but in many instances pressure skyrockets beyond a certain point. One of the jobs of the ballisticians is to determine that point, and then develop NEVER EXCEED loads. Your finding is a perfect example of why working up carefully is a mandatory safe reloading practice. Sometimes things get dangerous well before the max, it depends on the combination of components and gun, and how it's put together.

Gear

[44man]

I'd say that isn't typical, usually it's more like 15% per grain up near the top end, but in many instances pressure skyrockets beyond a certain point. One of the jobs of the ballisticians is to determine that point, and then develop NEVER EXCEED loads. Your finding is a perfect example of why working up carefully is a mandatory safe reloading practice. Sometimes things get dangerous well before the max, it depends on the combination of components and gun, and how it's put together.

Gear
I wish we lived close. :bigsmyl2:
Fast powders do need less changes and even 1/10 gr is important.
Get to H110 and 296 and 1/2 gr is good working loads.
Yet you are correct in that guys change other things that affect charges.
Some powders will spike real quick and even 2400 can get you in trouble if you fool around.
Our biggest problem is that all of our boolits are different and not covered in manuals. It can get scary when max pressure is reached well below a max book load.
I spent weeks and weeks trying to figure out what to load in my 45-70 BFR. I was told to hold under 30,000 PSI and all load info is in CUP. On top of that, I made the molds that do not match anything. I don't like to slide down a 30' razor blade with an iodine bath at the end! :veryconfu