If it was all done by Mc Gowen, why not let them figure it out? If it has the wrong twist or the wrong bore size, it's not like you can fix it without a new barrel anyway.
McGowen blank, chamber cut by a gunsmith or a McGowen cut chamber? Call the seller get your money back.
Frank
1st pic crown with tread protector 2nd with out tread protector 3rd pic another crown I have on another barrel all with 11° angle crownPost picture(s) of the crown…
Agreed. As it's turned down for threading it might be .001"-.002" loose at the muzzle, but that won't cause keyholes. Just crappy groups. Like 2-3 MOA IF it is in fact loose.nothing with that crown is going to cause a keyhole. Twist or diameter is the reason.
Post picture(s) of the crown…
1 in 7So....what did the twist check out to be???
Should be a quality barrel. I think the bearing length of the bullet is related to stability. Either the Berger or Sierra website that has a stability chart.25 creedmoor 1 in 7 twist. 26 inch. A round 30 shots , all keyholed. 133 berger , 117 sst,and 117 round nose bullets. All keyholing. Brass looks normal
But the crowd looks rough. I'm no machinist. And it's a McGowen barrel. Any suggestion?
On VarmintAls website I think he said he touches up the crown by hand spinning a fine round grinding stone on the muzzle like you might have on a Dremel tool. It's been att least 5 years since I read the article.Years ago, I read an article in a shooting magazine about rifle barrel crowns. I don't recall all the specifics, but the author intentionally damaged the crowns of several rifles to see the affect on accuracy. These experiments included cutting the barrel shorter and crooked with a hack saw, purposely filing a groove in the crown with a round file, dropping the muzzle repeatedly on concrete and probably a few other destructive tests I don't recall. The author was surprised that none of these damages severely affected the accuracy of the rifles. Obviously, they were not match rifles expected to shoot sub MOA groups, but the before/after accuracy tests were basically similar. They couldn't get a bullet to keyhole or dramatically off point of aim.
Scott
Start here.Bore scope it and see if the throat is rough and check the crown. I would also check the actual twist rate.