An Interesting read about Barrel lapping /superfinishing HW

[airbuddy3]

barrels for use on target pcp's ..from the BUll Durham forum

Hi Guy's,

I superfinished my two Weihrauch blanks by using a chinese TF79/22 with a plastic piece installed on the muzzle that was bored out to be a slip fit on the back end of the barrel with a o-ring groove cut in the plastic and a o-ring to seal on the outside of the barrel.

I started by cleaning the barrels with Boretechs rimfire blend (I made a slip fit bore guide out of the same plastic with a brass ferrel inserted in case the plastic galled my coated rod) using patches and nylon brushes. The patches came out quite orange with rust, even though the barrels had oil in them as they came from Tim, once clean I had a good look at them with a friends bore scope. The grooves looked pretty good but the tops of the lands looked quite rough like they had chatter marks on them (I am not sure what power a gradient lens borescope is but I guess 20-25x) but the marks probably were actually quite fine. I pushed some kodiaks into the bore and had a good look at the marks on them and the feathering on the skirt.

I then got some Clover SiC 1200 grit lapping compond and charged 5 28gn daesungs with 1200grit and pushed the first pellet into the bore so that the base was started into the bore about 1/16" (if this was not done the TF did not have enough puff to blow the pellet down the barrel) I shot one pellet and then cleaned the bore and had another look everything looked OK the 1200 was not excessively aggressive. I then repeated until all five were used up alternating bare and charged pellets (as per Larry's reccomendation) every 4 pellets I cleaned the barrel. I then reslugged the barrel and the pellets feathered about the same but the scratches imparted on the pellets was a litle finer and the pellets were smoother to push through the bore. The bore was looking noticeably cleaner with the borescope and the orange has gone.

Now I switched to 10 JB charged pellets and repeated the above. I reslugged again and the pellets were easier to push through the bore as there was less stick slip as the bore and lands had polished up. The marks left by the bore and rifling on the pellet look the same but the scratches on the pellet from passing through the bore are much finer. The feathering on the back has not changed in size but the feathers are smoother edged on their trailing edge. The bore with the borescope now looks really good and the tops of the lands have just lost the look of being very sharp the surface has lost its chatter like look. The choke in the muzzle is much easier to feel as the pellets slide down the bore very easily not catching on micro sharp edges.

I am very pleased with the result. Now I just need my Gladiator to turn up so that I can install one of the barrels and try it out.

Regards,

Craig


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