The bullet has a straight shank and then a tapered nose. The shortest you can seat the bullet is so that just a tiny bit of the straight shank is showing. Then you taper crimp onto that. This length will vary from bullet to bullet.
The longest you can seat a bullet is determined by either your chamber throat or the magazine. If you are going to stick with that bullet, seat it much longer, so it won't fit the mag, and then seat deeper and deeper until it does. Note that length. That is your mag length. It will be a similar length for other round nosed bullets, too. Flat points, like semi wad cutters will have to be seated a little deeper than that.
Then take one of these max mag rounds and chamber it. Did the slide close all the way? Eject the round and see if there is a mark all the way around the bullet, near the case mouth, from the chamber throat.
If so, seat bullets deeper and deeper until this marking stops. That is your true max length. You can now use any length between this max and the previous munimum, determined by where the straight shank stops.
I would then load 25 long, 25 short and 25 of something in between and see if one shoots much better or if one feeds much better.
Then try that length at 5.0 gr and 5.3gr of powder.
This is called load development. You might be shocked at how much these variables can impact groups and functioning.
Your round looks a little shorter and a bit milder than what I would use.
Welcome to reloading. A wonderful extra dimension to shooting.
I have just finished a similar test for my Colt Commander. I found that only a slight section of bullet shank can show above the case mouth before the bullet hits the chamber throat, so I have very little choice of OAL.
When I tried different powder choices, I found it grouped much better with a mild charge of powder. I had almost given up on it, since most 20 yard groups were the size of my hat until I tried a new powder and started with very mild loads and worked up. A charge just a bit more than the minimum required to work the action shot the best. In the picture you can see what a difference a half grain of powder makes with this gun.