I want to load cowboy loads in .45 colt for my howell conversion.
the problem is I can't find much data that's actually marked as cowboy loads.  
I especially can't find data that used the powders I have on hand.
I was planning on loading a RNFP somewhere around 250 grains.
I have a ton of winchester autocomp, a fair ammount of red dot, a little win 231, and mabey 1/4 LB of unique.

so I'm looking at 45 colt loads and I see tons of loads that fit into the 700-800 FPS range I've read that I should stay within, but they are not specifically listed as "cowboy loads".  are these safe?
is there a specific PSI I should just watch out for exceding?

I just want to know if I have to use data that says "cowboy" or if I just have to stay in that lower velocity range (or under a specific chamber presure)

Google trail boss powder

I know what it is but it's main ingredient is unobtanium.
I have to work with what I can get.

Cowboy data would be best since most conversions I have seen are not as stout as non conversion firearms.  Cowboy loads tend to be on the bottom end of the power spectrum and would be best for a conversion firearm.  With that said, Trailboss is a good powder and is not unobtainium.  I see it at local gun shows all the time and my uncle who loves to shoot .45 acp has been using Trailboss for a while now and just purchased some recently.  

Do an internet search for .45 Colt Cowboy Loads and you will find many different listings people use.

I see all kinds of loads that I THINK are OK but the lack of any real pressure or velocity specs on what constitutes a cowboy load leaves me unsure.

Go with the minimum load for that bullet weight and powder .

that's what I was thinking, but how do I be sure that even that is a safe pressure?
what is the max chamber pressure of a .45 colt black powder load?

Winchester 231 = HP-38
I use 6 gr. of HP-38 with a 250 gr bullet in my Kirst conversion cylinder in a 58 Remington / Pieta
Hodgon Cowboy action data calls for a min of 5.8 gr. to a max of 7.1 gr of HP-38
I hope this helps . You could post this in the reloading section or have a mod move it over to the reloading section for more info .
The guys in that section are very knowledgeable .
Good luck

I wanted to post it here because I thought I could find more people with experience in this type of loading in here.
I suppose I have gotten what I'll get in here so I have no problem with it if a mod is willing to move the thread to reloading to see if anyone in there has experience with it.