870 Sabot Load needed

[murf205]

I need a good 12 ga sabot load using Blue Dot or Unique for my 870 w/a 20" Hastings cantilever barrel. I have 50 cal sabots from Slugs R Us and have just ordered a 440 gr Lee 50 cal pistol mould. I've got 2 3/4" Cheddite hulls, .125 fiber wads, and .250 gas seal wads. I will roll crimp. The Blue Dot loads I am seeing are all over the map as far as starting to max loads and some do'nt state whether they were shot in a solid breech gun or a pump/auto. The Lee mould is a gas check but of course I will not use one since it will not be engraved by the rifling. The sabot weighs 70 grs and the boolit will probably weigh 440 grs or I can add lead till it does for total ejecta of around 510 grs. I have no way to pressure test so I'll let the chrono tell the story. I do'nt see many Unique loads mentioned and it may be too fast but I have an 8lb keg, soooo being the frugal(cheap) guy I am, I'd use it if it'll work but I'd scrap the Unique idea if not. If I am in the wrong burn rate I am certainly open to try a different powder. Thanks for any help. There are some of the most knowledgeable people in the sport here and we are lucky indeed to have such a venue.
Murf205

[Hogtamer]

Jmortimer has experience with Unique and I believe, Ed Hubel's sabots...

[jmort]

Never used 440 grain boolit with the Slugs R Us sabot, but I would start around 25 grains of Unique and go up to 27/28. I have tried two .575" balls, around 560 grains. Per Ed's recommendation flattened the lower ball a bit to set the top ball on. Started with 23 grains of Unique. Looks promising to 50 yards.

[murf205]

I did'nt know that SlugsRUs made a 440gr slug. Thats why I have a Lee 500S&W boolit mould ordered from Midsouth. Thanks for the starting point, what did you shoot these loads in?

[jmort]

I mis-read the O/P and see that he will be shooting the 440 grain Lee boolit in the Slugs R Us sabot. The Slugs R Us slug is .727 caliber solid wall sabot with double chevrons 420 grain pure lead Hammerhead slug. I assume the slug is .50" The data I suggested would work either way. Same sabot and similar weight slug/boolit. I use Unique and Blue Dot for shotgun, handgun, and rifle boolits/slugs.