3.5" Brass case fullsize .729 Slug for H&R Ultra Slug load data???

[meauxcg]

I've been reading over the 12GFH threads and load data.
I'm using a H&R ultra slug hunter. Found that the chamber will fit a 3.5 shell with in spec.
I'm using the fury custom bullets 615 grain full .729 diameter. On loading what determines the seating depth of the bullet/slug? When I use the various powder weights is is necessary to close the gap from the powder to the bullet with wads or is an air-gap acceptable? I'm looking to use the 3.5 brass that I have ordered.
I noticed that you used black powder substitute, guessing 777 in 3 -30grain pellets. I know that will keep the pressures low but is there any downside to using it in the brass shells or anything I need to look out for?

[Hogtamer]

Pls make sure 3 1/2" is stamped on the barrel. I don't know how much experience there is for your possible load to get suggestions.

[uncle dino]

No air gap within case...give me a call tonight. And we will go over what you want to do..d

[megasupermagnum]

The only ultra slug hunter that was ever chambered for a 3 1/2" was for 20 gauge, and they are rare. No 12 gauge ever came with a 3 1/2" chamber, and you do not want any of the case in the forcing cone.