That's the stock I have on my U-Mag, it is a Boyd's stock. I had the original laminate stock on it to begin with, then one of the original DWB'S on the old forum had a few T holes he was selling, I snagged it. He was from Roanoke, can't remember his name.
T-Bolts can shoot very well. Played with the Smokeless powders and T-7ff, But it takes a little work to get there.
I sold mine, but will never sell my U-mag
On the bore use a cleaning rod with a nylon brush, take 1-1/2" or 2" cotton patches that you smeared the JB on one side. 25 passes, another one.. 100 passes total. Clean the bore than use the other JB finish for 25 passes x4. Then thoroughly clean.
It will shine like a mirror and either improve...
Whites are like your kids, you love them all, each has a slightly different trait that shines.
UMAG, Super 91, Thunderbolt, Lightning, Tominator,..... I am trying to remember all my kids names.
I use 80gn of T7 ff with a green MMP Sabot, a 300gn .429 XTP. Good to 80 yds.
I have also shot BS pure lead out of them. I had two of them at one time, a synthetic SS barrel and a Laminate blue barrel. Paid 300 a piece for them. I still have the Synthetic SS.