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flounderman
02-01-2012, 09:06 AM
bore sighted a 7.7 jap at the neighbors mailbox, about 200 yards away. shot the rifle at about 30 yards and it was way low. kept cranking the scope up and shooting and when it got in the general area there was about 5 feet of difference between the bore sight and the actual adjustments. the end of the barrel has been sawed off, looks fairly straight. if it is crowned at all, it is slight. could the crown deflect a bullet that much or is the barrel bent? I'm probably going to cut it to 19 inches and attempt to crown it. anybody ever seen this problem?

theperfessor
02-01-2012, 12:50 PM
A bad crown can throw a bullet all over the place.

flounderman
02-01-2012, 04:44 PM
I cut the barrel to 19 inches. it looked like it could have been bent. there was a place where a front sight had been. cut the barrel with a hacksaw, by eye. filed it square by eye, crowned it with a dremel, again by eye. put the scoped barrel in a vise and bore sighted it again, assembled the gun and loaded 4 fire forming loads with 23 grains of 4198, the same charge I had been shooting lead with. loaded them with 125 grain full jacketed .310 bullets. I tried some paper patch I had left first. didn't appear to be patterning very good, but did manage to get the scope in the middle of the target. I adjusted it a few clicks after the first 125 grain hit close to the aim point. last three of the 125 grain cut a one hole cloverleaf at 30 yards, using a stepladder for a rest. I did about the same thing with a 7.7 jap over 50 years ago. loaded it with a case full of 4831 and pulled military bullets I assumed were 30-06. first group with that jap was an inch for 5 shots at 100 yards. I checked the bore sight after I was done shooting and it is right where it was supposed to be. crown could have been bad but I think the end of the barrel was bent or warped. maybe it had been heated when the front sight was put on or attempted to put on.

scrapcan
02-01-2012, 05:39 PM
Can you show us a picture of the group on the neighbor's mailbox?

saint_iverson
02-01-2012, 08:47 PM
+1 manley, tell them to order a bigger package next time

saint_iverson
02-01-2012, 08:49 PM
Anyways, 125Gr in the 7.7? Seems a little on the light side to me.

leadman
02-11-2012, 05:16 PM
I've cut military barrel and used a square on the end and filed it until it was flat. Then I used a Home Depot 45 degree countersink by hand. If you get the width of the angle the same all the way around the muzzle they usually shoot pretty good.

Is the Jap barrel straight for sections like a Mauser?