Ditto on the 5.4 gns of BE being just a little hot behind a 230 grainer.
Dadofmany, both your FNP and SIG are very tightly made guns, and should be capable of 1 1/2" groups or better at 25 yards.
I strongly disagree with the statement that you start with the hot loads and work down to find the sweet spot. There are a couple of reasons for this, first safety for you and the gun, second is barrel leading.
As you work up, you may begin to see pressure signs, flattened primers, etc. Stop. Don't be too proud to pull bullets if the load is getting too hot. I bulged a Browning Hi-Power barrel last year because I didn't stop when pressure signs appeared. I should have stopped immediately, the price of a new Browning barrel is about $600. I was lucky not to have blown something up. These were actually powder puff loads using about 3 grains of powder, but heavy bullets. Recoil and report were low, but the primers got flat flat flat. I shoulda stopped, expensive lesson learned.
Second reason for working up, is because at some point your loads will start to smear lead down the barrel as the load increases if you're shooting lead. Now, this isn't as bad as it seems, amazingly, if the pistol likes the load, it will shoot sub 2" groups with a horribly leadded barrel. But I have found there is a catch to this, only higher power loads that have enough pressure to substantially obturate the bullet will be accurate in a leadded barrel, lower pressure loads will spray all over the target with a leadded bore. This is why you would start a set with a clean barrel, then work up. Going the other way would obscure some potentially very accurate loads because of bore leadding by starting hot load first. And if you're shooting lead, hot loads will smear the bore.
Below is a picture showing a load my 1911 likes, 4.35 grains Titegroup behind a 200 cast lead RNFP. Upper left target is shot with unleadded barrel, then after shooting hotter rounds that did leave lead in the bore, I went back to the sweet load of 4.35, that is the target on the upper right, boolits sprayed all over hell. I could see the barrel had some leadding so I fired a few jacketed bullets to clear the barrel, then shot two more targets with the 4.35 load, and groups went right back into the black. Those are the two lower targets. That was an eye opener. The 4.35 runs at the upper end of not leadding the bore a bit, another .3 grains and the bore begins to streak. These targets are all fired at 25 yards.
Gordy is right, you will find the "sweet spot" by working up a load, but work up, low to high. Start with a load considerably lighter than listed in a loading table, say the max load is 5.4 grains of 700X behind a 200 grain SWC. Start at something like 3.8, then work up in .2 grain increments to the 5.4 grains max. I load 5 rounds of each powder weight, so the box of ammo would contain something like 3.8, 4.0. 4.2, 4,4, 4.6, 4.8, 5.0, 5.2, and 5.4 grains of powder. You could even include a 3.6 set so the box will have a full 50 rounds to shoot. Anyway, start at the low end with a clean barrel, shooting each 5 round set, log your load info on the target, as well as velocities, and notes about function and barrel leading. Some of the lower loads may not function the pistol, no biggy. Sometimes the pistol will be very accurate at low loadings, sometimes not. However, when you find the sweet spot, groups will go from like 3" down to an inch or so. You'll know when you're there.
What I have found about autoloaders is that they are more finicky about thier sweet spot than revolvers. In addition to obturation and interior ballistics, they seem to prefer certain recoil impulse levels. What i mean by this is that they like a certain amount of recoil impulse to make all their parts clang around consistantly shot to shot. I have found powders of similar burning rates gave similar accuracy results at similar velocities. The amount of powder to achieve this didn't matter, but similar recoil impulses seemed to bang the working parts in harmony or someting, and the groups got small.
That's a lot of info, I've been shooting blind for a lot of years, and am just now beginning to pay attention to things. Finding an accurate load and understanding it is quite a task indeed.
Some powders shoot more accurately than others. I have only gotten mediocre accuracy from my can of WW 231, never bad, never great. However, Titegroup has been an excellent performer for me in .45 ACP, midrange 9mm, and .38 spec. Bullseye has also worked very well for me in both .38 and .45 ACP. I used to shoot a lot of 700X in .45's as well, I have found some good loads with it too.
If you would like more information, on powders I have tried, boolits, loadings, etc, etc, feel free to e-mail me. I've been working on loads a lot lately.
Here's a picture of my lil darling, Springer mil-spec and her targets.
