Found this forum and this particular thread while looking for information on using a lathe to true up an AR-15 receiver.
The post(s) by 'bptactical' caught my attention. He confirmed my recent understanding that the lapping tools sold by several companies don't accomplish what they claim. They might smooth the mating surface for the barrel extension but do not square this surface to the axis of the receiver/barrel bore.
Had already been schooled on this by Joe Carlos, from YouTube. He has several videos there that are well worth viewing.
To make a long story short, 'bptactical' reinforced the direction I was headed in. Some 1" seamless aluminum pipe had been aquired, made of 6061-T6 alloy. This is the same material my Rock River Arms rifles are made of. I purchased a 1" expanding mandrel to hold the test piece and the RRA receiver:
Using dial indicators, the test piece was mounted on a lathe and test cuts made:
Satisfied with the results the receiver was carefully mounted on the expanding mandrel:
The facing cut was made:
This is a spare RRA upper receiver. I will be rebarreling my match gun down the road with a Krieger barrel. Will give that receiver the same treatment and bed the new barrel with a shim as needed and green 620 Loctite.
I'm very glad to have found this forum and the information contained within.
Jim
The post(s) by 'bptactical' caught my attention. He confirmed my recent understanding that the lapping tools sold by several companies don't accomplish what they claim. They might smooth the mating surface for the barrel extension but do not square this surface to the axis of the receiver/barrel bore.
Had already been schooled on this by Joe Carlos, from YouTube. He has several videos there that are well worth viewing.
To make a long story short, 'bptactical' reinforced the direction I was headed in. Some 1" seamless aluminum pipe had been aquired, made of 6061-T6 alloy. This is the same material my Rock River Arms rifles are made of. I purchased a 1" expanding mandrel to hold the test piece and the RRA receiver:
Using dial indicators, the test piece was mounted on a lathe and test cuts made:
Satisfied with the results the receiver was carefully mounted on the expanding mandrel:
The facing cut was made:
This is a spare RRA upper receiver. I will be rebarreling my match gun down the road with a Krieger barrel. Will give that receiver the same treatment and bed the new barrel with a shim as needed and green 620 Loctite.
I'm very glad to have found this forum and the information contained within.
Jim