Use a powder more suitable for the 20ga and forget about using fast powders like Red Dot. In some "special" circumstances, it may work, but you'd be far better off using a more appropriate powder for the 20 ga loads you wish to load.
I was using 11.6 gr of 700X and that felt fine to me but not for youngsters then I went to 11.6 gr of Solo 1000 and that is a very nice load . Relatively no recoil so I`ve been boxing these loads up for my grandkids to use .
Shoot the lowest pressure loads you can with Briley or Kolar tube sets. The 20 ga. tubes are relatively thin and they will eventually split if you insist on shooting fast burning powder/high pressure loads. Regular barrels are much more forgiving. Ron
RD is good for an A5 in the 20 I used 10gr and 1oz for many years didnt see any hard slams
I bought a 8 lb and it worked for 38s to 12ga and several 100 30-30 30-06 didnt know they made other powder in the 70s
A host of reputable industry sources produce reloading components. Most of them publish data as well. That's how the companies stay in business. It’s how their employees put bread on the table.
Nearly every reputable industry source includes WARNINGS about doing dumb stuff. I pay attention to industry recommendations and warnings for at least two good reasons:
1. Industry sources work with these issues every day. They are the most knowledgeable on the subject.
2. Their livelihood depends on safe and effective results.
When I have doubts about reloading, I look to reputable industry sources. So it was when I read Ricks1 post.
Our friend Ricks1 thinks Red Dot is just dandy pushing one ounce of shot from 20 gauge hulls. He also lists it for 30-30 and 30-06 center fire rifle cartridges.
Since these applications are beyond my experience, I looked at data from a number of Hercules and Alliant guides starting with data published Jan. 1970 and ending with 2008 data.
THERE ISN’T A SINGLE RECIPE FOR ONE OUNCE 20 GAUGE LOADS USING RED DOT.
THERE ISN’T A SINGLE RED DOT RECIPE FOR 30-30 OR 30-06 USING JACKETED BULLETS.
The reloadersnest.com website has a burn rate chart for 267 powders. They are listed from fastest to slowest. The lower the number, the faster the powder. Red Dot is number 17 on the list. By comparison, Alliant’s powder Reloader #7 is number 146.
Reloader #7 is significant because it is the first powder listed by Alliant as appropriate for either 30-30 or 30-06. Even then it is only appropriate for the lightest of bullets. Other Hercules/Alliant powders appropriate for 30-30 and 30-06 include Reloader 10X, 15, 17, and 19, 22, and 25. On the burn chart they are numbers 163, 198, 222, 237, and 249 respectively.
Neither Hercules nor Alliant has listed Red Dot for a one ounce pay load in at least the past 40 years. Similarly, all of their data for 30-30 and 30-06 list MUCH slower burning powders.
Perhaps Ricks1 is correct. Maybe Red Dot is the best powder ever for these applications. However, before anyone tries this home brewed sh!t, do yourself a favor.