I would not shoot those 1 3/4" shells given the pressure and likely lack of quality. There are so many better alternatives. Also I don't think you need to keep velocity bellow 1100...I would say 1200.

The 2 1/2" RST shells are very good. The 3/4oz. 12ga Ultra-lites are wonderful. I also like the 1oz. Maxi lites. The 7/8 oz RST 12 gauge are great too, but a little too much for me in some of my older and lighter guns at 1200fps(just my opinion).

For reloading, Red Dot works great in these lighter 12 gauge loads. This may be helpful: http://www.claybusterwads.com/images.../CB0175-12.pdf

Good luck!

Let me add to the above reloading data I posted, by saying I reduce my Red Dot load to 14-15grains for 3/4oz. Which works great!

Thanks for the reminder Drew. I'm always very cautious with these barrels.

Here's a 10 minute video of a procedure/components for reloading the 1 3/4" shot shells, for anyone that's curious.

For clarity, what is the relationship between velocity and psi. I'm trying to determine a safe powder/load ratio for my barrels.
I'm thinking 3/4oz and 7/8ozs.

I don't think there is a generalizable relationship between velocity and psi as they differ between powders and components.

However, for the same powder and components you can see trends. In that Clay Buster load data I posted you can see what an additional 1 grain of powder does to velocity and pressure. You can back off or add have a good idea of what velocity or pressure will be, though since I am usually reducing loads so I am not as concerned. Especially, when some of those Red Dot 3/4oz. loads are already in the 6000 psi range or less.

I think it is good to be cautious and understand what you are doing. And there is a lot of good light load data out there. Since I shoot a lot of RSTs and reload the empties, I would also recommend the Cheddite Reloading Manual(the type of hulls RST uses).

I would pick a good load and try it out. You can make a nice light 7/8oz load from Red Dot as well. I have a Mec 600 jr for every gauge I shoot 10-410. For the most part, I stick with a powder I like for each gauge for target shooting. My Mec 10ga. and 12ga. always have Red Dot in them.

Here a link to another thread when I was experimenting with 2 1/2" 12ga. 5/8 oz loads which I enjoyed. A few other members chimed in with their ultra light recipes. I am going to load some 5/8oz 12s using 14grains of Red Dot for a 2"12 sxs I recently got that weighs 5lbs 2ozs: http://parkerguns.org/forums/showthread.php?t=25879

Anybody know where I can buy some Alliant Extra Lite powder. It seems to be out of stock everywhere.

Unfortunately in today's market you have to watch, watch, and watch some more. Extra Lite was available last week but its availability lasted only a few hours. Things seem to be loosening up some so stay alert and be ready to jump.