Troy, this is what I do working up a new bullet:
1. First I determine the max OAL using the barrel out of the pistol (which you already did)
2. I then determine the IDEAL OAL for my pistol/barrel combination by incrementally decreasing the OAL (say 0.005") and manually feeding/chambering from the magazine until I get reliable feeding/chambering - I believe you determined this to be 1.155" for your pistol. (since I load for several pistols, I usually load 40S&W TCFP to 1.125" OAL - For match loads, longer OAL).
3. Next I work up my powder charge from the start charge and load incremental charge loads (10 rounds each charge) and range test to see which charge reliably cycles the slide and produce the most accurate shot groups.
is it common to increase pressure by seating the bullet deeper vs. adding more powder?
Yes, the shorter OAL will increase the chamber pressure; but once I determine the OAL that reliably feed/chamber well, I usually work with the powder charge to get at the accurate load.
when working up a load, how do you determine when to stop.
When I get reliably cycling of the slide regardless of the grip I use, including limp wristing, and consistent accurate shot groups.
I use an
8x11 copy paper target with one inch squares (PDF link) and write on the top right corner the bullet type and weight/powder charge/OAL/distance to target/where spent casing landed and felt recoil (light/mild/moderate/heavy - snappy vs push vs thump). I used to keep the targets in a 3-ring binder, but have transferred the information to a computer file for faster reference. For me, accurate shot group reference for semi-autos typically run around one inch shot groups at 7-10 yards and around 2 inches at 15 yards. Very accurate shot groups will produce 2-3 inches at 25 yards. Super accurate "The Load" like 5.0 gr of W231/HP38 with 45ACP 200/230 gr LSWC/RN is capable of producing one inch shot group at 25 yards.
I'm loading for practice rounds, but would like something similar to my SD round. Is it simply a matter of increasing the load till it "feels" right?
Factory JHP velocity data is available from the manufacturer's website, sometimes on the box or you can call the customer service number and ask. Note the length of barrel used for factory testing (if specified) as if you have a shorter barrel compact/subcompact, your muzzle velocities will be less than the longer test barrel. Using published load data (and also noting the length of test barrel used), compare the factory JHP velocity with your load data velocities BUT keep in mind that your pistol/barrel combo may not produce the same velocities.
Since factory/aftermarket barrels come with variations in bore diameter, different rifling, and gap before the start of the rifling; velocity generated in your pistol/barrel will be different. Also, OAL used for your reloads will affect how soon the bullet will engage the rifling and change the velocity. Coming close to factory velocity is the objective and you'll ultimately need a chrono to do that.
As to felt recoil, faster burning powders like Bullseye/Promo/Red Dot/Titegroup will produce more snappy recoil than W231/HP38/Unique/Universal/Power Pistol.
I try to duplicate same velocity, felt recoil and POA/POI as factory JHP using the same bullet weight for practice. Since
Golden Saber and
Gold Dot bullets are available in bulk, you can even use the same projectile to duplicate your SD practice rounds.
