i have been shooting goex ffg powder for only a little while now.i have been shooting pyradex for a long time,my wife bought me a tompson center inline that i shot a couple of years,but that was not realy primitive enough for me.i then got a pedersoli long percussion rifle and a bounty model 50 caliber percussion pistol.as stated in another post i aqquired a nice rifle that was built in 79/80.its a half stock hawkens,w.m.large barrel 31 1/2" in length with a set of rollers triggers on it.to the question.i ordered some 8 once and 10 once denim.8 oz.measures .017,and 10 oz. measures .023 on the flats of my calipers,squeezed as hard as possible.accuracy "for me" is to be able to shoot a 5 shot group into a cloverleaf hole at 100 yards,which i have achieved already,and to shoot a 5 shot group into 3" at 200 yards.i have not shot past 100 yet.my problem is,with a .490 rb,or a .495.when i use the .017 thick patch material i get great accuracy to 100 yards.when i use the thicker patchs my shots string out in a straight line or box up,and when i load past 80 grns of 2f i get a lot of sparks,flame out the end of the barrel.i have shot loads from 50 grns.,to 100 grns. 2f.i have not had the chance to try the 3f.i'm use a lube of water,alcohol,and neatsfoot oil,clean up with water,and use wd40 for final clean and storage.my question is why do's this rifle not like the tighter ball patch combo,and why the flame,sparks,after i go to 80+ grans.powder.thanks for all the info,help i have received since i joined this forum.you guys are a wealth of information.