Here are a few for you.
Graybeard outdoor forums
They have a section just for H&R guns.
Here is another great site for shotguns of any type.
Shotgun world
They have a forum just for slug shooters.
I hunted with the Gold mags in my USH and didn't get all that great performance out of them. They were good enough, but more than twice the group size at 100 yards than some other slugs I have tried. I wasn't overly impressed with the performance on a lung shot either. I mean it killed the deer but when I dressed it there was not a lot of damage. Not as much as an XTP bullet like my muzzle loader used, which are similar to what the high end slug loads use.
I shot my deer at 20 yards and it ran about 90 yards. I bet these slugs with a shoulder shot would anchor one where stands though. And I will be honest I have only shot one deer with them. Not a real great base for evaluation if you know what I mean.
I think I got around 5 inch groups at 100 yards with the gold magnums. I get around 2 inch groups or better with the winchester platinums. I have shot other rifled slugs that shot really well in it though. The more expensive winchester rifled slugs did really well in mine. Until the barrel fouls out, which is about 4 shots in my gun.
And I agree, that gun is going to KICK!! If you try the Gold mags let me know what you thought of them
. The platinums kick very hard as well, maybe as bad the gold mags.
Some will tell you because you have a rifled barrel you have to shoot sabot rounds. This is not true at all. Rifled barrels have been around longer than saboted slugs have. They were originally designed to increase the range of rifled slugs. It will NOT hurt your barrel. The soft lead they use in the slugs is MUCH softer than the steel used in your barrel. They are a PIA to clean though[:@]. I had some cheap rifled slugs shoot very well in my gun, but it makes a heck of a mess when you clean it. I have got some 3 shot one ragged hole groups out of rifled slugs that cost 4 bucks a box. I won't lie they are pretty tempting to use.
Since your gun is lighter than most slug guns you might also consider that remington makes some reduced recoil loads. If you are shooting inside 100 yards they still have plenty of power to take deer sized game with a well placed shot. And most slug hunters are not shooting farther than that anyway.
My opinions anyway.
Paul