Mash out

With a single infusion partial mash....
If I do my mash in my brewpot.

Should I just turn on the burner and heat the water to mash-out temp or should I add heated water? Is there any diff?

Also, how many of you pm'ers are doing mashouts? The last few batches I've done, I've had trouble reaching final gravity. I'm thinking that not doing a mash-out is part of the problem.

I doubt doing a mashout is hurting your final gravity. Mashing in your brewpot makes it hard to hold a steady temp, and that probably hurts more than anything else. Read Brew your own's countertop partial mash system
http://byo.com/feature/1536.html
and check out my system
https://www.homebrewtalk.com/showthread.php?t=61049
Cheap, easy, and very reliable. how big is your boil pot?

It sounds like you're mashing in a kettler, so I would say just go for it. Heat her up to reach mash-out. If you're using a cooler, then add the already heated water.
As for your FG issues, there could be many factors. Are you ending too high? Too low? Giving it enough time in the primary? Pitching enough yeast? Proper fermentation temps?

Heating the pot isn't a good idea unless you are very careful.

When I do a PM in the kettle, I just add a gallon of boiling water & tea-bag the VLGB.

i don't do a mash out at home, because with my electric burner it's impossible to regulate temperature.

when i do it at my friends pad, i heat and stir for 5-10 minutes until temp is reached. i usually stop 2 degrees short because it will continue to heat a bit after the burner is off.

really, you can do it either way.

if you're having trouble reaching FG, you may be mashing too high. are you using a floating thermometer? what are you mash temps? i usually stay around 152°F.

using the pot for heating can be rather inconsistent and you need to stir a lot to make sure you are at the right temp. hope you figure this out.

Mashing out (or not) isn't your issue. My guess: grain crush.