For next time...
I assume the bolster screws into the side of the barrel and holds the nipple,and the breech plug is conventional.
So,you have a hole for the bolster drilled and tapped through the barrel wall.
Most of the time when a hole is drilled,a burr is pushed forward on the side the drill breaks through.
So now,when you push a patch clear to the breech,the patch bridges over that hole and can snag.That is likely what happened.
And,of course,the crunchy fouling builds up at the breech.
What to do about it?
When I was building them,I picked up on the Hawken style hook breech.I used the Griffin.
No bolster,the fire is delivered through the breech plug.
And,the barrel is removed for a water cleaning by pulling two wedge keys.
Anyway,Many bolsters have a cleanout plug screw in the end of them.Easy to add.That can be a minimum impact access to used a probe to unsnag the patch material.Failing that,the bolster can be removed.I would not make a habit of it,though.
If possible,consider your patch size and jag style .If you can avoid having the patch edged going past the bolster hole it will help.
I always had good luck with the standard button typ brass jag with grooves.
A good split hickory ramrod works and is useful,but I don't use them for the range rod,
If you can find one,the GI one piece steel rod for the .50 BMG is great.