Grind down the tip of your parting blade you just have to do the very tip and you can re-sharpened it with a little effort
You also should look up the proper depth and width of the groove, it should be somewhere around 1.2 mm wide and .7mm deep for a good seal. Do look it up though, the prior is just a guess. Regards, Tom
Actually, it isn't sliding while under pressure.... I would allow for about 10% compression of the CS in that application.... A 1mm O-ring is just under 0.040", so the depth of the gland from the ID of the barrel to the bottom of the groove should be about 0.036".... I would make the width of the groove about 0.045"....Bob