I understand that but when lapping a barrel with a lead slug imbedded with an abrasive, your purpose is not to true the barrel, but to smooth out irregularities. All the ring lapping and truing bars that I have seen, including the set that I have are very hard machined steel. I guess the people selling those ring lapping/truing kits are just dumb old country boys like me. I'll pass on your words of wisdom to them.
You are just a dumb aze old country boy...
From the Sinclair catalog:
"Sinclair Scope Ring Lapping Tools ( 1 inch, 30mm, 34mm, 35mm) are made from ground accuracy stock stainless steel that has a tolerance of +/-.0005 inch. Each Sinclair Lapping Tool comes with the lapping bars are 10 inch in length, which gives you plenty of stroke length to quickly lap your scope rings."
"Ground accuracy stock" doesn't qualify as "very hard stock" what ever the ffuck that means...
Brownells lapping bar:
"SPECS: Mild steel, in-the-white. 12" (30cm) long, 1" (2.5cm) or 30mm (1.187") dia. Includes (2) plastic handles and instructions."
Please expound on your theory how a lap made out of a "very hard material" can be imbedded with abrasive and then form cut the base material. In 35 years of actual precision lapping I've NEVER seen or used a lap made out of "very hard material".