I was wondering if anyone has used RL19, RL22 or IMR7828 with 100gr bullets in the 6MM Rem, and if so what have you found to be best?

Well you gave me something to do at the range next time.
I have RE19 and 100g Hornady interlocks.

I,ve tried all but 7828 and right now my favorite is RL22. I'm getting 3/4" groups at 200yds with 100 gr Hornady SP. I also like H4831 getting 1.5" groups at 300 yds with it and the Hornady 87 gr SP. I'm using WW brass and Fed 210M primers.

glf127,
I have been shooting the 6mm ( 244) since 1966. I used to use H-4831 for all my loads, for the 75 to 100 gr. I have tried a lot of different power & bullets in that time. I swithched to R-19 for the 75 gr Hornady V-max, & the 85 & 95 gr. Barnes X's ( I use for deer). The accuracy inproved & the vel. increased by about 100fps ( no big deal) with the R-19.

5-shots at 200-yards.
Firearm: Ruger 77R in 6MM Remington with Leupold 9x optics
Case: Remington
Primer: Remington 9-1/2
Powder: 43.2 grains of IMR-4350
Bullet: Sierra 85 grain Hollow Point Boat Tail
Velocity: 3128 FPS @ 15' from muzzle

As for the powders you asked about:
http://stevespages.com/243_7_100.html

I prefer the mid range powders, but for the slower powders in a 57 mm case, RL 19 hands down. Especially with 100 grain or larger bullets in the 6mm Rem. I use RL 19 with 115 grain Berger VLD bullets for long range target work, with a MV of 3250 fps, and very very tight accuracy. Same also with 107 grain Sierras, in a Rifle with a 1 in 8 twist. ( Remington Long Action, not short action)

Cheers and Good shooting
seafire