Most of the British troops didn't use rifles, they used Brown Bess muskets, .72 caliber...They did have a few rifles that came over here...the Ferguson rifle, about 200 but we took them away from them after the Battle of Kings Mountain...
btw...The British did bring over troops from various areas of what is now Germany, about 25-30,000 total during the war...some of these (about 1500) were special light infantry, armed with Jaeger rifles, but there was no standard caliber, just as with the American Long Rifle...
A .72 caliber round ball weighs about 560 grains, if my memory is correct the standard powder charge was 70 grains...British General George Hanger (who captured several American riflemen and shipped back to England, with their rifles to show the British how well they could shoot) is quoted as saying that a good shot with a musket could hit a man at 80 yards, but at 150 he would miss, as long as he took aim careful at his target, whereas he noted that a rifleman could (and did) kill an individual at 2-300 yards...