Investarms is also the maker of Lyman. And so a Lyman part fits the Investarms. The rear sight and ramrod can be got from http://www.Cainsoutdoors.com
or RMCSports.com both of them carry Lyman parts. And the Super Rod from Cains is a very good quality rod that they will make to any length you want. Call them. They are very helpful. I have a Lyman Trade Rifle in .54 caliber. And I have a .50 caliber Lyman Trade Rifle. Both are great shooters.