Just got in to reloading and shot my first loads today.

Gun: XDm 9mm
Powder: Hodgdon Longshot, 5 gr.
Bullet: 115 Gr. Copper plated RN
Brass: Mixture
Primer: CCI No. 500

Shot 40 rounds total. Probably ever 3 rounds I was getting a stovepipe and the brass was pretty dirty. Using the data from Hodgdon's website I started out with 5 gr. of powder. Their maximum load is 6. Any input?  Gun shot flawlessly with factory rounds. Thanks!

It sounds to me like you need to work up a little more. Soot is a clue that your rounds don't have enough power to push the case walls out enough to seal the chamber letting pressure out the back. This could also cause the stovepipes.

I usually work up in .2 or .3 increments towards max. Probably .2 since it's not a huge span, and see where the gun runs with a little more powder.

Sound like loads still a little on the weak side to operate slide with some authority

Agree with the above. Your options are

1. Either work up... (5 is starting load for 9mm 115's according to Hodgdon - rarely do anyone find the starting load is optimized - I have yet)
2. Double check you got a good crimp - but not too much with plated. Higher crimp will increase pressure/burn
3. Verify seating depth is optimized. Shorter will increase pressure.

If you didn't have any feeding issues (try a couple pistols), 3 is not necessary.If crimp looks good (pull a bullet to see you got some marks but no tearing of the plate), then 2 is out.

Therefore, I would run up close to max with plated bullets and see how they go. Hodgdon lists max at 6gr with lead and Jacket bullets. Velocities barely hit 1200. That is well under what a plated bullet can run.  

I would run in .2gr increments up to max. Pressure signs at any time, stop (doubt you will see any). Reason I go to max? If you find that 5.8 is a great load in terms of target performance, you want to know that 6.0 isn't going to blow your pistol up. The powder measures will create variation so you need to be ready if a charge drops heavy.

Good luck!

P.S. 4th way to increase pressure is to run magnum primers which some people do. Longshot likes magnum primers in some of the bigger cartridges (not necessary in 9mm).

Your loads are too light. The Hodgdon website lists a starting weight of 5.0 gr up to a max of 6.0. I could not find data for 115 gr bullets in the Lee, Sierra, Speer, Lyman, Nosler, or Hornady manuals.

Load some more in .2 gr increments. Stove piping should stop before you hit 6.0 gr.

Thanks a ton, gentlemen.